BQ27541DRZR-G1

Sample & Buy Product Folder Technical Documents Support & Community Tools & Software bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 bq27541-G1 Single Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration 1 Features 2 Applications • • • • • • 1 • • • • • Battery Fuel Gauge for 1-Series (1sXp) Li-Ion Applications up to 14,500-mAh Capacity Microcontroller Peripheral Provides: – Accurate Battery Fuel Gauging Supports up to 14,500 mAh – Internal or External Temperature Sensor for Battery Temperature Reporting – SHA-1/HMAC Authentication – Lifetime Data Logging – 64 Bytes of Non-Volatile Scratch Pad FLASH Battery Fuel Gauging Based on Patented Impedance Track™ Technology – Models Battery Discharge Curve for Accurate Time-To-Empty Predictions – Automatically Adjusts for Battery Aging, Battery Self-Discharge, and Temperature/Rate Inefficiencies – Low-Value Sense Resistor (5 mΩ to 20 mΩ) Advanced Fuel Gauging Features – Internal Short Detection – Tab Disconnection Detection HDQ and I2C Interface Formats for Communication With Host System Small 12-pin 2,5 mm × 4 mm SON Package Smartphones Tablets Digital Still and Video Cameras Handheld Terminals MP3 or Multimedia Players 3 Description The Texas Instruments bq27541-G1 Li-ion battery fuel gauge is a microcontroller peripheral that provides fuel gauging for single-cell Li-ion battery packs. The device requires little system microcontroller firmware development for accurate battery fuel gauging. The fuel gauge resides within the battery pack or on the main board of the system with an embedded battery (nonremovable). The fuel gauge uses the patented Impedance Track™ algorithm for fuel gauging, and provides information such as remaining battery capacity (mAh), state-of-charge (%), run-time to empty (minimum), battery voltage (mV), and temperature (°C). It also provides detections for internal short or tab disconnection events. The fuel gauge also features integrated support for secure battery pack authentication, using the SHA1/HMAC authentication algorithm. Device Information (1) PART NUMBER bq27541-G1 (1) PACKAGE SON (12) BODY SIZE (NOM) 2.50 mm x 4.00 mm For all available packages, see the orderable addendum at the end of the datasheet. 4 Typical Application Battery Pack PACK+ Vcc REGIN LDO REG25 BAT SE SHDQ TS bq27541 SDA SCL SRP PROTECTION IC SRN Vss PACK- 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Typical Application ................................................ Revision History..................................................... Pin Configurations and Functions ....................... Specifications......................................................... 1 1 1 1 2 4 5 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 7.10 Absolute Maximum Ratings ...................................... 5 Handling Ratings....................................................... 5 Recommended Operating Conditions....................... 6 Thermal Information .................................................. 6 Power-on Reset ........................................................ 6 2.5-V LDO Regulator ............................................... 7 Internal Temperature Sensor Characteristics ........... 7 Internal Clock Oscillators .......................................... 7 Integrating ADC (Coulomb Counter) Characteristics 7 ADC (Temperature and Cell Voltage) Characteristics ........................................................... 7 7.11 Data Flash Memory Characteristics........................ 8 7.12 HDQ Communication Timing Characteristics ......... 8 7.13 I2C-Compatible Interface Timing Characteristics .... 9 8 Detailed Description ............................................ 10 8.1 8.2 8.3 8.4 8.5 8.6 9 Overview ................................................................. Functional Block Diagram ....................................... Feature Description................................................. Device Functional Modes........................................ Communications ..................................................... Programming........................................................... 10 11 12 22 25 29 Data Flash Interface............................................. 39 9.1 9.2 9.3 9.4 9.5 Accessing the Data Flash ....................................... Manufacturer Information Blocks ............................ Access Modes......................................................... SEALING or UNSEALING Data Flash .................... Data Flash Summary .............................................. 39 39 40 40 41 10 Application and Implementation........................ 46 10.1 Typical Applications .............................................. 46 11 Device and Documentation Support ................. 47 11.1 11.2 11.3 11.4 Documentation Support ........................................ Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 47 47 47 47 12 Mechanical, Packaging, and Orderable Information ........................................................... 47 5 Revision History Changes from Revision C (October 2012) to Revision D Page • Changed 32Ahr to 14,500-mAh.............................................................................................................................................. 1 • Changed 32 Ahr to 14,500 mAh............................................................................................................................................. 1 • Deleted minimum and maximum values for Power-on reset hysteresis. .............................................................................. 6 • Deleted lines for VDO, ΔV(REGTEMP), ΔV(REGLINE) and ΔV(REGLOAD) from Electrical Specifications tables. ................................. 7 • Deleted f(EIO), t(SXO) from Electrical Specifications tables for both oscillators and combined oscillators in single table.......... 7 • Changed typical value from 2.097 to 8.389 in Internal Clock Oscillators .............................................................................. 7 • Deleted minimum value of 8 in ADC (Temperature and Cell Voltage) Characteristics.......................................................... 7 • Added typical value of 5 in ADC (Temperature and Cell Voltage) Characteristics ................................................................ 7 • Changed MΩ to kΩ in ADC (Temperature and Cell Voltage) Characteristics........................................................................ 7 • Added t(TRND) line to Electrical Specifications tables .............................................................................................................. 8 • Added (20 typical) to T Rise value when Design Energy Scale = 1 .................................................................................... 13 • Added (2 typical) to T Rise value when Design Energy Scale = 10 .................................................................................... 13 • Changed wording in Internal Short Detection ...................................................................................................................... 21 • Changed description for SOC1 and SOCF to be more complete. ...................................................................................... 35 • Changed units for Avg P Last Run from mA to mW. ........................................................................................................... 44 Changes from Revision B (June 2012) to Revision C Page • Deleted section: Fast Qmax Update..................................................................................................................................... 15 • Changed the Detailed Configuration Register Descriptions section..................................................................................... 17 • Changed the FULLSLEEP Mode section. ............................................................................................................................ 23 • Changed text in the Executing an Authentication Query section ......................................................................................... 25 • Changed Sealed Access From: No To: Yes for 0x0005, 0x0007, 0x0010 in Table 15........................................................ 30 2 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 • Changed bit1-High Byte From CSV To: RSVD (Reserved) in Table 16 .............................................................................. 31 • Changed the SHUTDWN description in Table 16 ................................................................................................................ 31 • Changed text in the FW_VERSION: 0x000 section From: "The bq27541-G1 firmware version returns 0x0222." To: "The bq27541-G1 firmware version returns 0x0224." .......................................................................................................... 32 • Changed Table 27, CC Offset Data Flash (DF) column From: DF x 0.00048 To DF x 0.0048 and Board Offset Data Flash (DF) column From: DF x 16/0.48 To: DF x 0.0075..................................................................................................... 45 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 3 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Device Comparison Table PRODUCTION PART NO. (1) bq27541DRZR-G1 bq27541DRZT-G1 (1) (2) PACKAGE (2) TA COMMUNICATION FORMAT SON-12 –40°C to 85°C I2C, HDQ (1) TAPE AND REEL QUANTITY 3000 250 bq27541-G1 is shipped in I2C mode For the most current package and ordering information, see the Package Option Addendum at the end of this document; or, see the TI website at www.ti.com. 6 Pin Configurations and Functions bq27541 Pin Diagram (Top View) SE 1 12 HDQ REG25 2 11 SCL REGIN 3 10 SDA BAT 4 9 TS VCC 5 8 SRN VSS 6 7 SRP bq27541 Pin Functions PIN NAME NUMBER TYPE (1) BAT 4 I HDQ 12 I/O DESCRIPTION Cell-voltage measurement input. ADC input. Decouple with 0.1-μF capacitor. HDQ serial communications line (Slave). Open-drain. Use with 10-kΩ pullup resistor (typical) or leave floating when it is not used. REG25 2 P 2.5-V output voltage of the internal integrated LDO. Connect a minimum 0.47-μF ceramic capacitor. REGIN 3 P The input voltage for the internal integrated LDO. Connect a 0.1-μF ceramic capacitor. SCL 11 I Slave I2C serial communications clock input line for communication with system (Slave). Open-drain I/O. Use with 10-kΩ pullup resistor (typical). SDA 10 I/O Slave I2C serial communications data line for communication with system (Slave). Open-drain I/O. Use with 10-kΩ pullup resistor (typical). SE 1 O Shutdown Enable output. Push-pull output. Leave floating when it is not used. SRN 8 IA Analog input pin connected to the internal coulomb counter with a Kelvin connection where SRN is nearest the PACK– connection. Connect to 5-mΩ to 20-mΩ sense resistor. SRP 7 IA Analog input pin connected to the internal coulomb counter with a Kelvin connection where SRP is nearest the CELL– connection. Connect to 5-mΩ to 20-mΩ sense resistor TS 9 IA Pack thermistor voltage sense (use 103AT-type thermistor). ADC input VCC 5 P Processor power input. The minimum 0.47-μF capacitor connected to REG25 should be close to VCC. VSS 6 P Device ground (1) 4 I/O = Digital input/output, IA = Analog input, P = Power connection Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) VALUE MIN MAX UNIT VI Regulator input, REGIN –0.3 24 V VCC Supply voltage range –0.3 2.75 V VIOD Open-drain I/O pins (SDA, SCL, HDQ) –0.3 6 V VBAT BAT input (pin 4) –0.3 6 V VI Input voltage range to all others (pins 1, 7, 8, 9) –0.3 VCC + 0.3 V TF Functional temperature range –40 100 °C (1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 7.2 Handling Ratings Tstg Storage temperature range MIN MAX UNIT –65 150 °C Human Body Model (HBM), BAT pin V(ESD) Electrostatic discharge 1.5 Human Body Model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) Charge Device Model (CDM), per JEDEC specification JESD22C101, all pins (2) (1) (2) 2 –250 250 kV V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 5 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 7.3 Recommended Operating Conditions TA = -40°C to 85°C; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) MIN No operating restrictions TYP MAX 2.7 5.5 2.45 2.7 UNIT VI Supply voltage, REGIN ICC Normal operating mode current I(SLP) Low-power operating mode current (1) I(FULLSLP) Low-power operating mode current (1) I(HIB) Hibernate operating mode current VOL Output voltage low (HDQ, SDA, SCL, SE) IOL = 3 mA VOH(PP) Output high voltage (SE) IOH = –1 mA VCC – 0.5 VOH(OD) Output high voltage (HDQ, SDA, SCL) External pullup resistor connected to VCC VCC – 0.5 VIL Input voltage low (HDQ, SDA, SCL) –0.3 0.6 V VIH Input voltage high (HDQ, SDA, SCL) 1.2 6 V V(A1) Input voltage range (TS) VSS – 0.125 2 V V(A2) Input voltage range (BAT) VSS – 0.125 5 V V(A3) Input voltage range (SRP, SRN) VSS – 0.125 0.125 V Ilkg Input leakage current (I/O pins) tPUCD Power-up communication delay (1) No FLASH writes Fuel gauge in NORMAL mode. ILOAD > Sleep Current (1) (1) V 131 μA Fuel gauge in SLEEP mode. ILOAD < Sleep Current 60 μA Fuel gauge in FULLSLEEP mode. ILOAD < Sleep Current 21 μA Fuel gauge in HIBERNATE mode. Available in I2C mode only. ILOAD < Hibernate Current 6 μA 0.4 V V V μA 0.3 250 ms Specified by design. Not tested in production. 7.4 Thermal Information over operating free-air temperature range (unless otherwise noted) bq27541-G1 THERMAL METRIC (1) DRZ (12 PINS) RθJA Junction-to-ambient thermal resistance 64.1 RθJCtop Junction-to-case (top) thermal resistance 59.8 RθJB Junction-to-board thermal resistance 52.7 ψJT Junction-to-top characterization parameter 0.3 ψJB Junction-to-board characterization parameter 28.3 RθJCbot Junction-to-case (bottom) thermal resistance 2.4 (1) UNIT °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. 7.5 Power-on Reset TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER VIT+ Positive-going battery voltage input at VCC VHYS Power-on reset hysteresis 6 TEST CONDITIONS MIN TYP MAX 2.05 2.20 2.31 115 Submit Documentation Feedback UNIT V mV Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 7.6 2.5-V LDO Regulator (1) TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER VO IOS (1) (2) TEST CONDITION 2.7 V ≤ V(REGIN) ≤ 5.5 V, IOUT ≤ 16mA Regulator output voltage, REG25 (2) 2.45 V ≤ V(REGIN) < 2.7 V (low battery), IOUT ≤ 3mA Short circuit current limit V(REG25) = 0 V MIN TYP MAX 2.4 2.5 2.6 UNIT V TA = –40°C to 85°C 2.4 V TA = –40°C to 85°C 250 mA LDO output current, IOUT, is the total load current. LDO regulator should be used to power internal fuel gauge only. Specified by design. Not production tested. 7.7 Internal Temperature Sensor Characteristics TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER G(TEMP) TEST CONDITIONS MIN Temperature sensor voltage gain TYP MAX –2.0 UNIT mV/°C 7.8 Internal Clock Oscillators TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < (V(REGIN) = VBAT) < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT f(OSC) Operating frequency 8.389 MHz f(LOSC) Operating frequency 32.768 kHz 7.9 Integrating ADC (Coulomb Counter) Characteristics TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER VIN(SR) tCONV(SR) TEST CONDITIONS Input voltage range, V(SRN) and V(SRP) VSR = V(SRN) – V(SRP) Conversion time Single conversion Resolution VOS(SR) Input offset INL Integral nonlinearity error ZIN(SR) Effective input resistance (1) Ilkg(SR) Input leakage current (1) (1) MIN TYP –0.125 MAX UNIT 0.125 V 1 14 s 15 μV 10 ±0.007 bits ±0.034 2.5 FSR MΩ 0.3 μA Specified by design. Not production tested. 7.10 ADC (Temperature and Cell Voltage) Characteristics TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER VIN(ADC) Input voltage range tCONV(ADC) Conversion time TEST CONDITIONS Resolution VOS(ADC) Input offset Z(ADC1) Effective input resistance (TS) TYP MAX 1 14 (1) Effective input resistance (BAT) (1) Ilkg(ADC) Input leakage current (1) bq27541-G1 measuring cell voltage V ms 15 bits mV 5 bq27541-G1 not measuring cell voltage UNIT 125 1 Z(ADC2) (1) MIN –0.2 kΩ 8 MΩ 100 kΩ 0.3 μA Specified by design. Not production tested. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 7 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 7.11 Data Flash Memory Characteristics TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V (unless otherwise noted) PARAMETER TEST CONDITIONS TYP MAX 10 Flash programming write-cycles (1) Word programming time ICCPROG Flash-write supply current (1) UNIT Years 20,000 Cycles (1) tWORDPROG (1) MIN Data retention (1) tDR 5 2 ms 10 mA Specified by design. Not production tested. 7.12 HDQ Communication Timing Characteristics TA = –40°C to 85°C, CREG = 0.47 μF, 2.45 V < VREGIN = VBAT < 5.5 V; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 205 250 μs 0.5 50 μs 32 50 μs 86 145 μs 80 145 μs 190 950 μs μs t(CYCH) Cycle time, host to bq27541-G1 190 t(CYCD) Cycle time, bq27541-G1 to host 190 t(HW1) Host sends 1 to bq27541-G1 t(DW1) bq27541-G1 sends 1 to host t(HW0) Host sends 0 to bq27541-G1 t(DW0) bq27541-G1 sends 0 to host t(RSPS) Response time, bq27541-G1 to host t(B) Break time 190 μs t(BR) Break recovery time 40 μs t(RISE) HDQ line rising time to logic 1 (1.2V) t(TRND) Turnaround time (time from the falling edge of the last transmitted bit of 8-bit data and the falling edge of the next Break signal) 950 ns μs 210 1.2V t(BR) t(B) t(RISE) (b) HDQ line rise time (a) Break and Break Recovery t(DW1) t(HW1) t(DW0) t(CYCD) t(HW0) t(CYCH) (d) Gauge Transmitted Bit (c) Host Transmitted Bit Break 7-bit address 1-bit R/W 8-bit data t(RSPS) (e) Gauge to Host Response Figure 1. Timing Diagrams 8 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 7.13 I2C-Compatible Interface Timing Characteristics TA = –40°C to 85°C, CREG = 0.47μF, 2.45 V < VREGIN = VBAT < 5.5 V; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 300 ns 300 ns tr SCL/SDA rise time tf SCL/SDA fall time tw(H) SCL pulse width (high) 600 ns tw(L) SCL pulse width (low) 1.3 μs tsu(STA) Setup for repeated start 600 ns td(STA) Start to first falling edge of SCL tsu(DAT) Data setup time th(DAT) Data hold time tsu(STOP) Setup time for stop tBUF Bus free time between stop and start fSCL Clock frequency 600 ns 1000 ns 0 ns 600 ns 66 μs 400 tSU(STA) tw(H) tf tw(L) tr kHz t(BUF) SCL SDA td(STA) tsu(STOP) tf tr th(DAT) tsu(DAT) REPEATED START STOP START Figure 2. I2C-Compatible Interface Timing Diagrams Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 9 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8 Detailed Description 8.1 Overview The bq27541-G1 fuel gauge accurately predicts the battery capacity and other operational characteristics of a single Li-based rechargeable cell. It can be interrogated by a system processor to provide cell information, such as state-of-charge (SOC) and time-to-empty (TTE). Information is accessed through a series of commands, called Standard Commands. Further capabilities are provided by the additional Extended Commands set. Both sets of commands, indicated by the general format Command( ), are used to read and write information contained within the fuel gauge control and status registers, as well as its data flash locations. Commands are sent from system to gauge using the serial communications engine, and can be executed during application development, pack manufacture, or end-equipment operation. Cell information is stored in the fuel gauge in non-volatile flash memory. Many of these data flash locations are accessible during application development. They cannot, generally, be accessed directly during end-equipment operation. Access to these locations is achieved by either use of the companion evaluation software, through individual commands, or through a sequence of data-flash-access commands. To access a desired data flash location, the correct data flash subclass and offset must be known. The fuel gauge provides 64 bytes of user-programmable data flash memory, partitioned into two (2) 32-byte blocks: Manufacturer Info Block A and Manufacturer Info Block B. This data space is accessed through a data flash interface. For specifics on accessing the data flash, see Manufacturer Information Block. The key to the high-accuracy gas gauging prediction is Texas Instruments proprietary Impedance Track™ algorithm. This algorithm uses cell measurements, characteristics, and properties to create state-of-charge predictions that can achieve less than 1% error across a wide variety of operating conditions and over the lifetime of the battery. The fuel gauge measures charge and discharge activity by monitoring the voltage across a small-value series sense resistor (5 mΩ to 20 mΩ, typical) located between the CELL– and the battery PACK– pin. When a cell is attached to the fuel gauge, cell impedance is learned based on cell current, cell open-circuit voltage (OCV), and cell voltage under loading conditions. The fuel gauge external temperature sensing is optimized with the use of a high-accuracy negative temperature coefficient (NTC) thermistor with R25 = 10 kΩ ± 1% and B25/85 = 3435 kΩ ± 1% (such as Semitec 103AT) for measurement. The fuel gauge can also be configured to use its internal temperature sensor. The fuel gauge uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection functionality. To minimize power consumption, the fuel gauge has different power modes: NORMAL, SLEEP, FULLSLEEP, and HIBERNATE. The fuel gauge passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly. More details can be found in Device Functional Modes. NOTE The following formatting conventions are used in this document: Commands: italics with parentheses( ) and no breaking spaces, for example: RemainingCapacity( ) Data Flash: italics, bold, and breaking spaces, for example: Design Capacity Register Bits and Flags: italics with brackets[ ], for example: [TDA] Data Flash Bits: italics, bold, and brackets[ ], for example: [LED1] Modes and States: All capitals, for example: UNSEALED mode 10 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.2 Functional Block Diagram REGIN LDO POR REG25 VCC HFO BAT CC HFO SRN LFO HFO/128 4R HFO/128 SRP MUX ADC R Wake Comparator TS Internal Temp Sensor VCC 5k HFO/4 SDA SE 22 I2C Slave Engine Instruction ROM 22 CPU VSS SCL I/O Controller Instruction FLASH HDQ Slave Engine 8 Wake and Watchdog Timer GP Timer and PWM Data SRAM HDQ 8 Data FLASH Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 11 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.3 Feature Description 8.3.1 Fuel Gauging The fuel gauge measures the cell voltage, temperature, and current to determine battery SOC based on Impedance Track™ algorithm (Please refer to Application Report SLUA450, Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm, for more information). The fuel gauge monitors charge and discharge activity by sensing the voltage across a small-value resistor (5 mΩ to 20 mΩ, typical) between the SRP and SRN pins and in series with the cell. By integrating charge passing through the battery, the battery SOC is adjusted during battery charge or discharge. The total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. When an application load is applied, the impedance of the cell is measured by comparing the OCV obtained from a predefined function for present SOC with the measured voltage under load. Measurements of OCV and charge integration determine chemical state of charge and chemical capacity (Qmax). The initial Qmax values are taken from a cell manufacturers' data sheet multiplied by the number of parallel cells. It is also used for the value in Design Capacity. The fuel gauge acquires and updates the batteryimpedance profile during normal battery usage. It uses this profile, along with SOC and the Qmax value, to determine FullChargeCapacity( ) and StateOfCharge( ), specifically for the present load and temperature. FullChargeCapacity( ) is reported as capacity available from a fully charged battery under the present load and temperature until Voltage( ) reaches the Terminate Voltage. NominalAvailableCapacity( ) and FullAvailableCapacity( ) are the uncompensated (no or light load) versions of RemainingCapacity( ) and FullChargeCapacity( ) respectively. The fuel gauge has two flags accessed by the Flags( ) function that warns when the battery SOC has fallen to critical levels. When RemainingCapacity( ) falls below the first capacity threshold, specified in SOC1 Set Threshold, the [SOC1] (State of Charge Initial) flag is set. The flag is cleared once RemainingCapacity( ) rises above SOC1 Clear Threshold. All units are in mAh. When RemainingCapacity( ) falls below the second capacity threshold, SOCF Set Threshold, the [SOCF] (State of Charge Final) flag is set, serving as a final discharge warning. If SOCF Set Threshold = –1, the flag is inoperative during discharge. Similarly, when RemainingCapacity( ) rises above SOCF Clear Threshold and the [SOCF] flag has already been set, the [SOCF] flag is cleared. All units are in mAh. The fuel gauge has two additional flags accessed by the Flags() function that warns of internal battery conditions. The fuel gauge monitors the cell voltage during relaxed conditions to determine if an internal short has been detected. When this condition occurs, [ISD] will be set. The fuel gauge also has the capability of detecting when a tab has been disconnected in a 2-cell parallel system by actively monitoring the SOH. When this conditions occurs, [TDD] will be set. 8.3.2 Impedance Track™ Variables The fuel gauge has several data flash variables that permit the user to customize the Impedance Track™ algorithm for optimized performance. These variables are dependent upon the power characteristics of the application as well as the cell itself. 8.3.2.1 Load Mode Load Mode is used to select either the constant-current or constant-power model for the Impedance Track™ algorithm as used in Load Select (see Load Select). When Load Mode is 0, the Constant Current Model is used (default). When Load Mode is 1, the Constant Power Model is used. The CONTROL_STATUS [LDMD] bit the status of Load Mode. 8.3.2.2 Load Select Load Select defines the type of power or current model to be used to compute load-compensated capacity in the Impedance Track™ algorithm. If Load Mode = 0 (Constant Current), then the options presented in Table 1 are available. 12 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 Feature Description (continued) Table 1. Constant-Current Model Used When Load Mode = 0 LOAD SELECT VALUE 0 CURRENT MODEL USED Average discharge current from previous cycle: There is an internal register that records the average discharge current through each entire discharge cycle. The previous average is stored in this register. 1 (default) Present average discharge current: This is the average discharge current from the beginning of this discharge cycle until present time. 2 Average current: based off the AverageCurrent( ) 3 Current: based off of a low-pass-filtered version of AverageCurrent( ) (τ = 14s) 4 Design capacity / 5: C Rate based off of Design Capacity /5 or a C / 5 rate in mA. 5 Use the value specified by AtRate( ) 6 Use the value in User_Rate-mA: This gives a completely user-configurable method. If Load Mode = 1 (Constant Power) then the following options are available: Table 2. Constant-Power Model Used When Load Mode = 1 LOAD SELECT VALUE POWER MODEL USED 0 Average discharge power from previous cycle: There is an internal register that records the average discharge power through each entire discharge cycle. The previous average is stored in this register. 1 Present average discharge power: This is the average discharge power from the beginning of this discharge cycle until present time. 2 Average current × voltage: based off the AverageCurrent( ) and Voltage( ). 3 Current × voltage: based off of a low-pass-filtered version of AverageCurrent( ) (τ = 14s) and Voltage( ) 4 Design energy / 5: C Rate based off of Design Energy /5 or a C / 5 rate in mA . 5 Use the value specified by AtRate( ) 6 Use the value in User_Rate-Pwr. This gives a completely user-configurable method. 8.3.2.3 Reserve Cap-mAh Reserve Cap-mAh determines how much actual remaining capacity exists after reaching 0 RemainingCapacity( ), before Terminate Voltage is reached when Load Mode = 0 is selected. A loaded rate or no-load rate of compensation can be selected for Reserve Cap by setting the [RESCAP] bit in the Pack Configuration data flash register. 8.3.2.4 Reserve Energy Reserve Energy determines how much actual remaining capacity exists after reaching 0 RemainingCapacity( ) which is equivalent to 0 remaining power, before Terminate Voltage is reached when Load Mode = 1 is selected. A loaded rate or no-load rate of compensation can be selected for Reserve Cap by setting [RESCAP] bit in the Pack Configuration data flash register. 8.3.2.5 Design Energy Scale Design Energy Scale is used to select the scale and unit of a set of data flash parameters. The value of Design Energy Scale can be either 1 or 10 only, other values are not supported. For battery capacities larger than 6 Ah, Design Energy Scale = 10 is recommended. Table 3. Data Flash Parameter Scale/Unit Based on Design Energy Scale DATA FLASH DESIGN ENERGY SCALE = 1 (Default) DESIGN ENERGY SCALE = 10 Design Energy mWh cWh Reserve Energy mWh cWh Avg Power Last Run mW cW User Rate-Pwr mWh cWh T Rise No Scale (20 typical) Scaled by ×10 (2 typical) Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 13 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.3.2.6 Dsg Current Threshold This register is used as a threshold by many functions in the fuel gauge to determine if actual discharge current is flowing into or out of the cell. The default for this register should be sufficient for most applications. This threshold should be set low enough to be below any normal application load current but high enough to prevent noise or drift from affecting the measurement. 8.3.2.7 Chg Current Threshold This register is used as a threshold by many functions in the fuel gauge to determine if actual charge current is flowing into or out of the cell. The default for this register should be sufficient for most applications. This threshold should be set low enough to be below any normal charge current but high enough to prevent noise or drift from affecting the measurement. 8.3.2.8 Quit Current, Dsg Relax Time, Chg Relax Time, and Quit Relax Time The Quit Current is used as part of the Impedance Track™ algorithm to determine when the fuel gauge enters relaxation mode from a current flowing mode in either the charge direction or the discharge direction. The value of Quit Current is set to a default value that should be above the standby current of the system. Either of the following criteria must be met to enter relaxation mode: 1. | AverageCurrent( ) | < | Quit Current | for Dsg Relax Time. 2. | AverageCurrent( ) | < | Quit Current | for Chg Relax Time. After about 6 minutes in relaxation mode, the fuel gauge attempts to take accurate OCV readings. An additional requirement of dV/dt < 1 µV/s is required for the fuel gauge to perform Qmax updates. These updates are used in the Impedance Track™ algorithms. It is critical that the battery voltage be relaxed during OCV readings and that the current is not higher than C/20 when attempting to go into relaxation mode. Quit Relax Time specifies the minimum time required for AverageCurrent( ) to remain above the QuitCurrent threshold before exiting relaxation mode. 8.3.2.9 Qmax Qmax contains the maximum chemical capacity of the active cell profiles, and is determined by comparing states of charge before and after applying the load with the amount of charge passed. They also correspond to capacity at low rate of discharge, such as C/20 rate. For high accuracy, this value is periodically updated by the fuel gauge during operation. Based on the battery cell capacity information, the initial value of chemical capacity should be entered in Qmax field. The Impedance Track™ algorithm will update this value and maintain it in the Pack profile. 8.3.2.10 Update Status The Update Status register indicates the status of the Impedance Track™ algorithm. Table 4. Update Status Definitions UPDATE STATUS STATUS 0x02 Qmax and Ra data are learned, but Impedance Track™ is not enabled. This should be the standard setting for a golden image. 0x04 Impedance Track™ is enabled but Qmax and Ra data are not learned. 0x05 Impedance Track™ is enabled and only Qmax has been updated during a learning cycle. 0x06 Impedance Track™ is enabled. Qmax and Ra data are learned after a successful learning cycle. This should be the operation setting for end equipment. This register should only be updated by the fuel gauge during a learning cycle or when IT_ENABLE subcommand is received. Refer to the application note How to Generate Golden Image for Single-Cell Impedance Track™Device (SLUA544) for learning cycle details. 8.3.2.11 Avg I Last Run The fuel gauge logs the current averaged from the beginning to the end of each discharge cycle. It stores this average current from the previous discharge cycle in this register. This register should never need to be modified. It is only updated by the fuel gauge when required. 14 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.3.2.12 Avg P Last Run The fuel gauge logs the power averaged from the beginning to the end of each discharge cycle. It stores this average power from the previous discharge cycle in this register. To get a correct average power reading the fuel gauge continuously multiplies instantaneous current times Voltage( ) to get power. It then logs this data to derive the average power. This register should never need to be modified. It is only updated by the fuel gauge when required. 8.3.2.13 Delta Voltage The fuel gauge stores the maximum difference of Voltage( ) during short load spikes and normal load, so the Impedance Track™ algorithm can calculate remaining capacity for pulsed loads. It is not recommended to change this value. 8.3.2.14 Ra Tables and Ra Filtering Related Parameters These tables contain encoded data and are automatically updated during device operation. The fuel gauge has a filtering process to eliminate unexpected fluctuations in Ra values while the Ra values are being updated. The DF parameters RaFilter, RaMaxDelta, MaxResfactor, and MinResfactor control the Filtering process of Ra values. RaMaxDelta limits the change in Ra values to an absolute magnitude. MinResFactor and MaxResFactor parameters are cumulative filters which limit the change in Ra values to a scale on a per discharge cycle basis. These values are Data Flash configurable. No further user changes should be made to Ra values except for reading or writing the values from a prelearned pack (part of the process for creating golden image files). 8.3.2.15 MaxScaleBackGrid MaxScaleBackGrid parameter limits the resistance grid point after which back scaling will not be performed. This variable ensures that the resistance values in the lower resistance grid points remain accurate while the battery is at a higher DoD state. 8.3.2.16 Max DeltaV, Min DeltaV Maximum or minimum value allowed for Delta Voltage, which will be subtracted from simulated voltage during remaining capacity simulation. 8.3.2.17 Qmax Max Delta % Maximum change of Qmax during one update, as percentage of Design Capacity. If the gauges attempts to change Qmax exceeds this limit, changed value will be capped to old value ± DesignCapacity × QmaxMaxDelta / 100. 8.3.2.18 Fast Resistance Scaling When Fast Resistance Scaling is enabled by setting the [FConvEn] bit in Pack Configuration B, the algorithm improves accuracy at the end of discharge. The RemainingCapacity() and StateOfCharge() should smoothly converge to 0. The algorithm starts convergence improvements when cell voltage goes below (Terminate Voltage + Term V Delta) or StateofCharge() goes below Fast Scale Start SOC. For most applications, the default value of Term V Delta and Fast Scale Start SOC are recommended. Also it is recommended to keep (Terminate Voltage + Term V Delta) below 3.6V for most battery applications. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 15 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.3.2.19 StateOfCharge() Smoothing When operating conditions change (such as temperature, discharge current, and resistance, and so on), it can lead to large changes of compensated battery capacity and battery capacity remaining. These changes can result in large changes of StateOfCharge(). When [SmoothEn] is enabled in Pack Configuration C, the smoothing algorithm injects gradual changes of battery capacity when conditions vary. This results in a gradual change of StateOfCharge() and can provide a better end-user experience for StateOfCharge() reporting. The RemainingCapacity(), FullChargeCapacity(), and StateOfCharge() are modified depending on [SmoothEn] as below. [SmoothEn] RemainingCapacity() FullChargeCapacity() StateOfCharge() 0 UnfilteredRM() UnfilteredFCC() UnfilteredRM() / UnfilteredFCC() 1 FilteredRM() FilteredFCC() FilteredRM() / FilteredFCC() 8.3.2.20 DeltaV Max Delta Maximum change of Delta V value. If attempted change of the value exceeds this limit, change value will be capped to old value ±DeltaV Max Delta. 8.3.2.21 Lifetime Data Logging Parameters The Lifetime Data logging function helps development and diagnosis with the fuel gauge. Note that IT_ENABLE needs to be enabled (Command 0x0021) for lifetime data logging functions to be active. The fuel gauge logs the lifetime data as specified in the Lifetime Data and Lifetime Temp Samples data Flash subclasses. The data log recordings are controlled by the Lifetime Resolution data flash subclass. The Lifetime Data Logging can be started by setting the IT_ENABLE bit and setting the Update Time register to a non-zero value. Once the Lifetime Data Logging function is enabled, the measured values are compared to what is already stored in the Data Flash. If the measured value is higher than the maximum or lower than the minimum value stored in the Data Flash by more than the "Resolution" set for at least one parameter, the entire Data Flash Lifetime Registers are updated after at least LTUpdateTime. LTUpdateTime sets the minimum update time between DF writes. When a new maximum or minimum is detected, a LT Update window of [update time] second is enabled and the DF writes occur at the end of this window. Any additional max/min value detected within this window will also be updated. The first new max/min value detected after this window will trigger the next LT Update window. Internal to the fuel gauge, there exists a RAM maximum/minimum table in addition to the DF maximum/minimum table. The RAM table is updated independent of the resolution parameters. The DF table is updated only if at least one of the RAM parameters exceeds the DF value by more than resolution associated with it. When DF is updated, the entire RAM table is written to DF. Consequently, it is possible to see a new maximum or minimum value for a certain parameter even if the value of this parameter never exceeds the maximum or minimum value stored in the Data Flash for this parameter value by the resolution amount. The Life Time Data Logging of one or more parameters can be reset or restarted by writing new default (or starting) values to the corresponding Data Flash registers through sealed or unsealed access as described below. However, when using unsealed access, new values will only take effect after device reset The logged data can be accessed as RW in unsealed mode from Lifetime Data SubClass (SubClass ID = 59) of Data Flash. Lifetime data may be accessed (RW) when sealed using a process identical Manufacturer Info Block B. The DataFlashBlock command code is 4. Note only the first 32 bytes of lifetime data (not resolution parameters) can be RW when sealed. See Manufacturer Information Block for sealed access. The logging settings such as Temperature Resolution, Voltage Resolution, Current Resolution, and Update Time can be configured only in unsealed mode by writing to the Lifetime Resolution Subclass (SubClassID = 66) of the Data Flash. The Lifetime resolution registers contain the parameters which set the limits related to how much a data parameter must exceed the previously logged maximum/minimum value to be updated in the lifetime log. For example, V must exceed MaxV by more than Voltage Resolution to update MaxV in the Data Flash. 16 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.3.3 Detailed Configuration Register Descriptions 8.3.3.1 Pack Configuration Register Some bq27541-G1 pins are configured via the Pack Configuration data flash register, as indicated in Table 5. This register is programmed and read via the methods described in Accessing the Data Flash. The register is located at subclass = 64, offset = 0. Table 5. Pack Configuration Bit Definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 High Byte RESCAP CALEN INTPOL INTSEL RSVD IWAKE RSNS1 RSNS0 Default = 0 0 0 1 0 0 0 1 0x11 Low Byte GNDSEL RFACTSTEP SLEEP RMFCC SE_PU SE_POL SE_EN TEMPS Default = 0 1 1 1 0 1 1 1 0x77 RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set. CALEN = Calibration mode is enabled. INTPOL = Polarity for Interrupt pin. (See Interrupt Mode) INTSEL = Interrupt pin select: 0 = SE pin, 1 = HDQ pin. (See Interrupt Mode) RSVD = Reserved. Must be 0. IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (See Wake-Up Comparator). GNDSEL = The ADC ground select control. The VSS (pin 6) is selected as ground reference when the bit is clear. Pin 7 is selected when the bit is set. RFACTSTEP = Enables Ra step up/down to Max/Min Res Factor before disabling Ra updates. SLEEP = The fuel gauge can enter sleep, if operating conditions allow. True when set. (See Sleep Mode) RMFCC = RM is updated with the value from FCC, on valid charge termination. True when set. (See Detection Charge Termination) SE_PU = Pullup enable for SE pin. True when set (push-pull). (See Shutdown Mode) SE_POL = Polarity bit for SE pin. SE is active high when set (makes SE high when gauge is ready for shutdown). (See Shutdown Mode) SE_EN = Indicates if set the shutdown feature is enabled. True when set. (See Shutdown Mode for details.) TEMPS = Selects external thermistor for Temperature( ) measurements. True when set. (See Temperature Measurement and the TS Input) Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 17 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.3.3.2 Pack Configuration B Register Some bq27541-G1 pins are configured via the Pack Configuration B data flash register, as indicated in Table 6. This register is programmed and read via the methods described in Accessing the Data Flash. The register is located at subclass = 64, offset = 2. Table 6. Pack Configuration B Bit Definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 ChgDoDEoC SE_TDD VconsEN SE_ISD RSVD LFPRelax DoDWT FConvEn 1 0 1 0 0 1 1 1 Default = 0x67 ChgDoDEoC = Enable DoD at EoC recalculation during charging only. True when set. Default setting is recommended. SE_TDD = Enable Tab Disconnection Detection. True when set. (See Tab Disconnection Detection) VconsEN = Enable voltage consistency check. True when set. Default setting is recommended. SE_ISD = Enable Internal Short Detection. True when set. (See Internal Short Detection) RSVD = Reserved. Must be 0 LFPRelax = Enable LiFePO4 long relaxation mode. True when set. DoDWT = Enable DoD weighting feature of gauging algorithm. This feature can improve accuracy during relaxation in a flat portion of the voltage profile, especially when using LiFePO4 chemistry. True when set. FConvEn = Enable fast convergence algorithm. Default setting is recommended. (See Fast Resistance Scaling) 8.3.3.3 Pack Configuration C Register Some bq27541-G1 algorithm settings are configured via the Pack Configuration C data flash register, as indicated in Table 7. This register is programmed and read via the methods described in Accessing the Data Flash. The register is located at subclass = 64, offset = 3. Table 7. Pack Configuration C Bit Definition Default = bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 RSVD RSVD RelaxRCJumpOK SmoothEn SleepWkChg RSVD RSVD RSVD 0 0 0 1 1 0 0 0 0x18 RSVD = Reserved. Must be 0. RelaxRCJumpOK = Allow SOC to change due to temperature change during relaxation when SOC smoothing algorithm is enabled. True when set. SmoothEn = Enable SOC smoothing algorithm. True when set. (See StateOfCharge Smoothing) SleepWkChg = Enables compensation for the passed charge missed when waking from SLEEP mode. 18 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.3.4 System Control Function The fuel gauge provides system control functions which allows the fuel gauge to enter shutdown mode in order to power-off with the assistance of external circuit or provides interrupt function to the system. Table 8 shows the configurations for SE and HDQ pins. Table 8. SE and HDQ Pin Functions COMMUNICATION MODE [INTSEL] I2C 0 (default) (2) Interrupt Mode HDQ I2C 1 (1) SE PIN FUNCTION HDQ PIN FUNCTION Not Used (1) HDQ Mode (2) Interrupt Mode Shutdown Mode HDQ HDQ Mode (2) [SE_EN] bit in Pack Configuration can be enabled to use [SE] and [SHUTDWN] bits in CONTROL_STATUS() function; The SE pin shutdown function is disabled. HDQ pin is used for communication and HDQ Host Interrupt Feature is available. 8.3.4.1 Shutdown Mode In the shutdown mode, the SE pin is used to signal external circuit to power-off the fuel gauge. This feature is useful to shutdown the fuel gauge in a deeply discharged battery to protect the battery. By default, the Shutdown Mode is in normal state. By sending the SET_SHUTDOWN subcommand or setting the [SE_EN] bit in Pack Configuration register, the [SHUTDWN] bit is set and enables the shutdown feature. When this feature is enabled and [INTSEL] is set, the SE pin can be in normal state or shutdown state. The shutdown state can be entered in HIBERNATE mode (only if HIBERNATE mode is enabled due to low cell voltage), all other power modes will default SE pin to normal state. Table 9 shows the SE pin state in normal or shutdown mode. The CLEAR_SHUTDOWN subcommand or clearing [SE_EN] bit in the Pack Configuration register can be used to disable shutdown mode. The SE pin will be high impedance at power-on reset (POR), the [SE_POL] does not affect the state of SE pin at POR. Also, [SE_PU] configuration changes will only take effect after POR. In addition, the [INTSEL] only controls the behavior of the SE pin; it does not affect the function of [SE] and [SHUTDWN] bits. Table 9. SE Pin State SHUTDOWN Mode [INTSEL] = 1 and ([SE_EN] or [SHUTDOWN] = 1) [SE_PU] [SE_POL] NORMAL State 0 0 High Impedance SHUTDOWN State 0 0 1 0 High Impedance 1 0 1 0 1 1 0 1 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 19 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.3.4.2 Interrupt Mode By utilizing the interrupt mode, the system can be interrupted based on detected fault conditions as specified in Table 12. The SE or HDQ pin can be selected as the interrupt pin by configuring the [INTSEL] bit based on . In addition, the pin polarity and pullup (SE pin only) can be configured according to the system needs as described in Table 10 or Table 11. Table 10. SE Pin in Interrupt Mode ([INTSEL] = 0) [SE_PU] [INTPOL] INTERRUPT CLEAR 0 0 High Impedance INTERRUPT SET 0 0 1 0 High Impedance 1 0 1 0 1 1 0 1 Table 11. HDQ Pin in Interrupt Mode ([INTSEL] = 1) [INTPOL] INTERRUPT CLEAR INTERRUPT SET 0 High Impedance 0 1 0 High Impedance Table 12. Interrupt Mode Fault Conditions INTERRUPT CONDITION Flags() STATUS BIT ENABLE CONDITION SOC1 Set/Clear [SOC1] Always The SOC1 Set/Clear interrupt is based on the[SOC1] Flag condition when RemainingCapacity() reaches the SOC1 Set or Clear threshold in the Data Flash. Over Temperature Charge [OTC] OT Chg Time ≠ 0 The [OTC] Flag is set/clear based on conditions specified in Over-Temperature: Charge. Over Temperature Discharge [OTD] OT Dsg Time ≠ 0 The [OTD] Flag is set/clear based on conditions specified in Over-Temperature: Discharge. Battery High [BATHI] Always The [BATHI] Flag is set/clear based on conditions specified in Battery Level Indication. Battery Low [BATLOW] Always The [BATLOW] Flag is set/clear based on conditions specified in Battery Level Indication. Internal Short Detection [ISD] [SE_ISD] = 1 in Pack Configuration B The [SE_ISD] Flag is set/clear based on conditions specified in Internal Short Detection. Tab disconnection detection [TDD] [SE_TDD] = 1 in Pack Configuration B The [TDD] Flag is set/clear based on conditions specified in Tab Disconnection Detection. COMMENT 8.3.4.3 Battery Level Indication The fuel gauge can indicate when battery voltage has fallen below or risen above predefined thresholds. The [BATHI] bit of Flags() is set high to indicate Voltage() is above the BH Set Volt Threshold for a predefined duration set in the BH Volt Time. This flag returns to low once battery voltage is below or equal the BH Clear Volt threshold. It is recommended that the BH Set Volt Threshold is configured higher than the BH Clear Volt threshold to provide proper voltage hysteresis. The [BATLOW] bit of Flags() is set high to indicate Voltage() is below the BL Set Volt Threshold for predefined duration set in the BL Volt Time. This flag returns to low once battery voltage is above or equal the BL Clear Volt threshold. It is recommended that the BL Set Volt Threshold is configured lower than the BL Clear Volt threshold to provide proper voltage hysteresis. The [BATHI] and [BATLOW] flags can be configured to control the interrupt pin (SE or HDQ) by enabling interrupt mode. See Interrupt Mode for details. 20 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.3.4.4 Internal Short Detection The fuel gauge can indicate detection of an internal battery short if the [SE_ISD] bit in Pack Configuration B is set. The device compares the self-discharge current calculated in relaxation mode and AverageCurrent() measured in the system. The self-discharge rate is measured at 1-hour interval. When battery SelfDischargeCurrent() is less than the predefined (–Design Capacity / ISD Current threshold), the [ISD] of Flags() is set high. The [ISD] of Flags() can be configured to control interrupt pin (SE or HDQ) by enabling interrupt mode. See Interrupt Mode for details. 8.3.4.5 Tab Disconnection Detection The fuel gauge can indicate tab disconnection by detecting change of StateOfHealth(). This feature is enabled by setting [SE_TDD] bit in Pack Configuration B. The [TDD] of Flags() is set when the ratio of current StateOfHealth() divided by the previous StateOfHealth() reported is less than TDD SOH Percent. The [TDD] of Flags() can be configured to control an interrupt pin (SE or HDQ) by enabling interrupt mode. See Interrupt Mode for details. 8.3.5 Temperature Measurement and the TS Input The fuel gauge measures the battery temperature via the TS input to supply battery temperature status information to the fuel gauging algorithm and charger-control sections of the gauge. Alternatively, the gauge can also measure internal temperature via its on-chip temperature sensor, but only if the [TEMPS] bit of Pack Configuration register is cleared. Regardless of which sensor is used for measurement, a system processor can request the current battery temperature by calling the Temperature( ) function (see Standard Data Commands for specific information). The thermistor circuit requires the use of an external 10-kΩ thermistor with negative temperature coefficient (NTC) thermistor with R25 = 10 kΩ ± 1% and B25/85 = 3435 kΩ ± 1% (such as Semitec 103AT) that connects between the VCC and TS pins. Additional circuit information for connecting the thermistor to the bq27541 is shown in Typical Applications. 8.3.6 Over-Temperature Indication 8.3.6.1 Over-Temperature: Charge If during charging, Temperature( ) reaches the threshold of OT Chg for a period of OT Chg Time and AverageCurrent( ) ≥ Chg Current Threshold, then the [OTC] bit of Flags( ) is set. When Temperature( ) falls to OT Chg Recovery, the [OTC] of Flags( ) is reset. If OT Chg Time = 0, the feature is disabled. 8.3.6.2 Over-Temperature: Discharge If during discharging, Temperature( ) reaches the threshold of OT Dsg for a period of OT Dsg Time, and AverageCurrent( ) ≤ –Dsg Current Threshold, then the [OTD] bit of Flags( ) is set. When Temperature( ) falls to OT Dsg Recovery, the [OTD] bit of Flags( ) is reset. If OT Dsg Time = 0, the feature is disabled. 8.3.7 Charging and Charge Termination Indication 8.3.7.1 Detection Charge Termination For proper fuel gauge operation, the cell charging voltage must be specified by the user. The default value for this variable is in the data flash Charging Voltage. The fuel gauge detects charge termination when: • During 2 consecutive periods of Current Taper Window, the AverageCurrent( ) is < Taper Current • During the same periods, the accumulated change in capacity > 0.25 mAh / Current Taper Window • Voltage( ) > Charging Voltage – Taper Voltage Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 21 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com When this occurs, the [CHG] bit of Flags( ) is cleared. Also, if the [RMFCC] bit of Pack Configuration is set, RemainingCapacity( ) is set equal to FullChargeCapacity( ). When TCA_Set is set to –1, it disables the use of the charger alarm threshold. In that case, TerminateCharge is set when the taper condition is detected. When FC_Set is set to –1, it disables the use of the full charge detection threshold. In that case, the [FC] bit is not set until the taper condition is met. 8.3.7.2 Charge Inhibit The fuel gauge can indicate when battery temperature has fallen below or risen above predefined thresholds (Charge Inhibit Temp Low and Charge Inhibit Temp High, respectively). In this mode, the [CHG_INH] of Flags( ) is made high to indicate this condition, and is returned to its low state, once battery temperature returns to the range [Charge Inhibit Temp Low + Temp Hys, Charge Inhibit Temp High – Temp Hys]. 8.4 Device Functional Modes The fuel gauge has three power modes: NORMAL, SLEEP, and HIBERNATE. In NORMAL mode, the fuel gauge is fully powered and can execute any allowable task. In SLEEP mode the fuel gauge exists in a reduced-power state, periodically taking measurements and performing calculations. Finally, in HIBERNATE mode, the fuel gauge is in a very low power state, but can be awoken by communication or certain I/O activity. The relationship between these modes is shown in Figure 3. Details are described in the sections that follow. POR Exit From HIBERNATE VCELL < POR threshold Exit From HIBERNATE Communication Activity NORMAL OR bq27541 clears Control Status [HIBERNATE] = 0 Recommend Host also set Control Status [HIBERNATE] = 0 Fuel gauging and data updated every 1s Exit From SLEEP Pack Configuration [SLEEP] = 0 OR | AverageCurrent( ) | > Sleep Current OR Current is Detected above IWAKE Entry to SLEEP Pack Configuration [SLEEP] = 1 AND | AverageCurrent( ) |≤ Sleep Current SLEEP Fuel gauging and data updated every 20 seconds HIBERNATE Wakeup From HIBERNATE Communication Activity AND Comm address is NOT for bq27541 Disable all bq27541 subcircuits except GPIO. Entry to WAITFULLSLEEP If Full Sleep Wait Time > 0, Exit From WAITFULLSLEEP Entry to FULLSLEEP Guage ignores Control Status Any Communication Cmd If Full Sleep Wait Time = 0, [FULLSLEEP] Host must set Control Status [FULLSLEEP]=1 Exit From WAIT_HIBERNATE Cell not relaxed OR | AverageCurrent() | =>Hibernate Current Exit From WAIT_HIBERNATE VCELL < Hibernate Voltage (Supports SE pin shutdown function) WAITFULLSLEEP FULLSLEEP Count Down Entry to FULLSLEEP Count 0) or be cleared (Full Sleep Wait Time ≤ 0) after exit of FULLSLEEP mode. Therefore, EVSW communication activity might cause the gauge to exit FULLSLEEP MODE and display the [FULLSLEEP] bit as clear. The execution of SET_FULLSLEEP to set [FULLSLEEP] bit is required when Full Sleep Wait Time ≤ 0 in order to re-enter FULLSLEEP mode. While in FULLSLEEP mode, the fuel gauge can suspend serial communications as much as 4 ms by holding the comm line(s) low. This delay is necessary to correctly process host communication, since the fuel gauge processor is mostly halted in SLEEP mode. The fuel gauge exits FULLSLEEP if any entry condition is broken, specifically when: (1) AverageCurrent( ) rises above Sleep Current, or (2) a current in excess of IWAKE through RSENSE is detected when the IWAKE comparator is enabled. 8.4.4 HIBERNATE Mode HIBERNATE mode should be used for long-term pack storage or when the host system needs to enter a lowpower state, and minimal gauge power consumption is required. This mode is ideal when the host is set to its own HIBERNATE, SHUTDOWN, or OFF modes. The gauge waits to enter HIBERNATE mode until it has taken a valid OCV measurement (cell relaxed) and the magnitude of the average cell current has fallen below Hibernate Current. When the conditions are met, the fuel gauge can enter HIBERNATE due to either low cell voltage or by having the [HIBERNATE] bit of the CONTROL_STATUS register set. The gauge will remain in HIBERNATE mode until any communication activity appears on the communication lines and the address is for bq27541. In addition, the SE pin shutdown mode function is supported only when the fuel gauge enters HIBERNATE due to low cell voltage. When the gauge wakes up from HIBERNATE mode, the [HIBERNATE] bit of the CONTROL_STATUS register is cleared. The host is required to set the bit to allow the gauge to re-enter HIBERNATE mode if desired. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 23 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Device Functional Modes (continued) Because the fuel gauge is dormant in HIBERNATE mode, the battery should not be charged or discharged in this mode, because any changes in battery charge status will not be measured. If necessary, the host equipment can draw a small current (generally infrequent and less than 1 mA, for purposes of low-level monitoring and updating); however, the corresponding charge drawn from the battery will not be logged by the gauge. Once the gauge exits to NORMAL mode, the IT algorithm will take about 3 seconds to re-establish the correct battery capacity and measurements, regardless of the total charge drawn in HIBERNATE mode. During this period of reestablishment, the gauge reports values previously calculated prior to entering HIBERNATE mode. The host can identify exit from HIBERNATE mode by checking if Voltage() < Hibernate Voltage or [HIBERNATE] bit is cleared by the gauge. If a charger is attached, the host should immediately take the fuel gauge out of HIBERNATE mode before beginning to charge the battery. Charging the battery in HIBERNATE mode will result in a notable gauging error that will take several hours to correct. It is also recommended to minimize discharge current during exit from HIBERNATE. Note: The HIBERNATE mode is only available in I2C mode and is disabled when HDQ mode is used. 8.4.5 Power Control 8.4.5.1 Reset Functions When the fuel gauge detects a software reset by sending [RESET] Control( ) subcommand, it determines the type of reset and increments the corresponding counter. This information is accessible by issuing the command Control( ) function with the RESET_DATA subcommand. 8.4.5.2 Wake-Up Comparator The wake up comparator is used to indicate a change in cell current while the fuel gauge is in SLEEP modes. Pack Configuration uses bits [RSNS1, RSNS0] to set the sense resistor selection. Pack Configuration also uses the [IWAKE] bit to select one of two possible voltage threshold ranges for the given sense resistor selection. An internal interrupt is generated when the threshold is breached in either charge or discharge directions. Setting both [RSNS1] and [RSNS0] to 0 disables this feature. Table 13. IWAKE Threshold Settings (1) (1) IWAKE RSNS1 RSNS0 Vth(SRP-SRN) 0 0 0 Disabled 1 0 0 Disabled 0 0 1 1.0 mV or –1.0 mV 1 0 1 2.2 mV or –2.2 mV 0 1 0 2.2 mV or –2.2 mV 1 1 0 4.6 mV or –4.6 mV 0 1 1 4.6 mV or –4.6 mV 1 1 1 9.8 mV or –9.8 mV The actual resistance value vs the setting of the sense resistor is not important just the actual voltage threshold when calculating the configuration. The voltage thresholds are typical values under room temperature. 8.4.5.3 Flash Updates Data Flash can only be updated if Voltage( ) ≥ Flash Update OK Voltage. Flash programming current can cause an increase in LDO dropout. The value of Flash Update OK Voltage should be selected such that the VCC voltage does not fall below its minimum of 2.4 V during Flash write operations. 8.4.6 Autocalibration The fuel gauge provides an autocalibration feature that will measure the voltage offset error across SRP and SRN from time-to-time as operating conditions change. It subtracts the resulting offset error from normal sense resistor voltage, VSR, for maximum measurement accuracy. 24 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 Autocalibration of the ADC begins on entry to SLEEP mode, except if Temperature( ) is ≤ 5°C or Temperature( ) ≥ 45°C. The fuel gauge also performs a single offset calibration when: (1) the condition of AverageCurrent( ) ≤ 100 mA and (2) {voltage change since last offset calibration ≥ 256 mV} or {temperature change since last offset calibration is greater than 8°C for ≥ 60 seconds}. Capacity and current measurements will continue at the last measured rate during the offset calibration when these measurements cannot be performed. If the battery voltage drops more than 32 mV during the offset calibration, the load current has likely increased considerably; hence, the offset calibration will be aborted. 8.5 Communications 8.5.1 Authentication The fuel gauge can act as a SHA-1/HMAC authentication slave by using its internal engine. Sending a 160-bit SHA-1 challenge message to the fuel gauge will cause the gauge to return a 160-bit digest, based upon the challenge message and a hidden, 128-bit plain-text authentication key. If this digest matches an identical one generated by a host or dedicated authentication master, and when operating on the same challenge message and using the same plain text keys, the authentication process is successful. 8.5.2 Key Programming (Data Flash Key) By default, the fuel gauge contains a default plain-text authentication key of 0x0123456789ABCDEFFEDCBA9876543210. This default key is intended for development purposes. It should be changed to a secret key and the part immediately sealed, before putting a pack into operation. Once written, a new plain-text key cannot be read again from the fuel gauge while in SEALED mode. Once the fuel gauge is UNSEALED, the authentication key can be changed from its default value by writing to the Authenticate( ) Extended Data Command locations. A 0x00 is written to BlockDataControl( ) to enable the authentication data commands. The DataFlashClass() is issued 112 (0x70) to set the Security class. Up to 32 bytes of data can be read directly from the BlockData() (0x40 through 0x5F) and the authentication key is located at 0x48 (0x40 + 0x08 offset) to 0x57 (0x40 + 0x17 offset). The new authentication key can be written to the corresponding locations (0x48 to 0x57) using the BlockData() command. The data is transferred to the data flash when the correct checksum for the whole block (0x40 to 0x5F) is written to BlockDataChecksum() (0x60). The checksum is (255 – x) where x is the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis. Once the authentication key is written, the gauge can then be SEALED again. 8.5.3 Key Programming (Secure Memory Key) As the name suggests, the secure-memory authentication key is stored in the secure memory of the fuel gauge. If a secure-memory key has been established, only this key can be used for authentication challenges (the programmable data flash key is not available). The selected key can only be established or programmed by special arrangements with TI, using the TI Secure B-to-B Protocol. The secure-memory key can never be changed or read from the fuel gauge. 8.5.4 Executing an Authentication Query To execute an authentication query in UNSEALED mode, a host must first write 0x01 to the BlockDataControl( ) command, to enable the authentication data commands. If in SEALED mode, 0x00 must be written to DataFlashBlock( ), instead. Next, the host writes a 20-byte authentication challenge to the Authenticate( ) address locations (0x40 through 0x53). After a valid checksum for the challenge is written to AuthenticateChecksum( ), the bq27541-G1 uses the challenge to perform the SHA-1/HMAC computation, in conjunction with the programmed key. The bq27541-G1 completes the SHA-1/HMAC computation and write the resulting digest to Authenticate(), overwriting the preexisting challenge. The host should wait at least 45 ms to read the resulting digest. The host may then read this response and compare it against the result created by its own parallel computation. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 25 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Communications (continued) 8.5.5 HDQ Single-pin Serial Interface The HDQ interface is an asynchronous return-to-one protocol where a processor sends the command code to the fuel gauge. With HDQ, the least significant bit (LSB) of a data byte (command) or word (data) is transmitted first. Note that the DATA signal on pin 12 is open-drain and requires an external pullup resistor. The 8-bit command code consists of two fields: the 7-bit HDQ command code (bits 0:6) and the 1-bit RW field (MSB bit 7). The RW field directs the fuel gauge either to: • Store the next 8 or 16 bits of data to a specified register, or • Output 8 bits of data from the specified register The HDQ peripheral can transmit and receive data as either an HDQ master or slave. HDQ serial communication is normally initiated by the host processor sending a break command to the fuel gauge. A break is detected when the DATA pin is driven to a logic-low state for a time t(B) or greater. The DATA pin should then be returned to its normal ready high logic state for a time t(BR). The fuel gauge is now ready to receive information from the host processor. The fuel gauge is shipped in the I2C mode. TI provides tools to enable the HDQ peripheral. The SLUA408 application report provides details of HDQ communication basics. 8.5.6 HDQ Host Interruption Feature The default fuel gauge behaves as an HDQ slave only device when HDQ mode is enabled. If the HDQ interrupt function is enabled, the fuel gauge is capable of mastering and also communicating to a HDQ device. There is no mechanism for negotiating who is to function as the HDQ master and care must be taken to avoid message collisions. The interrupt is signaled to the host processor with the fuel gauge mastering an HDQ message. This message is a fixed message that will be used to signal the interrupt condition. The message itself is 0x80 (slave write to register 0x00) with no data byte being sent as the command is not intended to convey any status of the interrupt condition. The HDQ interrupt function is disabled by default and needs to be enabled by command. When the SET_HDQINTEN subcommand is received, the fuel gauge will detect any of the interrupt conditions and assert the interrupt at 1-second intervals until the CLEAR_HDQINTEN command is received or the count of HDQHostIntrTries has lapsed. The number of tries for interrupting the host is determined by the data flash parameter named HDQHostIntrTries. 8.5.6.1 Low Battery Capacity This feature will work identically to SOC1. It will use the same data flash entries as SOC1 and will trigger interrupts as long as SOC1 = 1 and HDQIntEN = 1. 8.5.6.2 Temperature This feature will trigger an interrupt based on the OTC (Over-Temperature in Charge) or OTD (Over-Temperature in Discharge) condition being met. It uses the same data flash entries as OTC or OTD and will trigger interrupts as long as either the OTD or OTC condition is met and HDQIntEN = 1. 26 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 Communications (continued) 8.5.7 I2C Interface The fuel gauge supports the standard I2C read, incremental read, one-byte write quick read, and functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as 1010101. The 8-bit device address is therefore 0xAA or 0xAB for write or read, respectively. Host Generated S 0 A ADDR[6:0] Fuel Gauge Generated A CMD[7:0] A P DATA[7:0] S A 1 ADDR[6:0] (a) S ADDR[6:0] DATA[7:0] N P (b) 0 A CMD[7:0] A Sr 1 ADDR[6:0] A DATA[7:0] N P ... DATA[7:0] (c) S ADDR[6:0] 0 A A Sr CMD[7:0] ADDR[6:0] 1 A DATA[7:0] A N P (d) Figure 4. Supported I2C Formats (a) (b) (c) (d) 1-byte write Quick read 1 byte-read Incremental read (S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop) The quick read returns data at the address indicated by the address pointer. The address pointer, a register internal to the I2C communication engine, increments whenever data is acknowledged by the fuel gauge or the I2C master. The quick writes function in the same manner and are a convenient means of sending multiple bytes to consecutive command locations (such as two-byte commands that require two bytes of data). Attempt to write a read-only address (NACK after data sent by master): S ADDR[6:0] 0 A A CMD[7:0] A DATA[7:0] P Attempt to read an address above 0x7F (NACK command): S 0 ADDR[6:0] CMD[7:0] A N P Attempt at incremental writes (NACK all extra data bytes sent): S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] A DATA[7:0] N A ... ... N P Incremental read at the maximum allowed read address: S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] 1 A DATA[7:0] Address 0x7F Data From addr 0x7F DATA[7:0] N P Data From addr 0x00 The I2C engine releases both SDA and SCL if the I2C bus is held low for t(BUSERR). If the fuel gauge was holding the lines, releasing them frees the master to drive the lines. If an external condition is holding either of the lines low, the I2C engine enters the low-power sleep mode. 8.5.7.1 I2C Time Out The I2C engine will release both SDA and SCL if the I2C bus is held low for about 2 seconds. If the fuel gauge was holding the lines, releasing them will free for the master to drive the lines. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 27 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Communications (continued) 8.5.7.2 I2C Command Waiting Time To make sure the correct results of a command with the 400-kHz I2C operation, a proper waiting time should be added between issuing command and reading results. For subcommands, the following diagram shows the waiting time required between issuing the control command the reading the status with the exception of the checksum command. A 100-ms waiting time is required between the checksum command and reading result. For read-write standard commands, a minimum of 2 seconds is required to get the result updated. For read-only standard commands, there is no waiting time required, but the host should not issue all standard commands more than two times per second. Otherwise, the gauge could result in a reset issue due to the expiration of the watchdog timer. S ADDR[6:0] 0 A CMD[7:0] A DATA [7:0] S ADDR[6:0] 0 A CMD[7:0] A Sr ADDR[6:0] A 1 A DATA [7:0] A P DATA [7:0] 66ms A DATA [7:0] N P A DATA [7:0] A 66ms Waiting time between control subcommand and reading results S ADDR[6:0] DATA [7:0] 0 A A CMD[7:0] DATA [7:0] A Sr N P ADDR[6:0] 1 A DATA [7:0] 66ms Waiting time between continuous reading results 8.5.7.3 I2C Clock Stretching I2C clock stretches can occur during all modes of fuel gauge operation. In the SLEEP and HIBERNATE modes, a short clock stretch will occur on all I2C traffic as the device must wake-up to process the packet. In NORMAL and SLEEP+ modes, clock stretching will only occur for packets addressed for the fuel gauge. The timing of stretches will vary as interactions between the communicating host and the gauge are asynchronous. The I2C clock stretches may occur after start bits, the ACK/NAK bit and first data bit transmit on a host read cycle. The majority of clock stretch periods are small (≤ 4 ms) as the I2C interface peripheral and CPU firmware perform normal data flow control. However, less frequent but more significant clock stretch periods may occur when data flash (DF) is being written by the CPU to update the resistance (Ra) tables and other DF parameters such as Qmax. Due to the organization of DF, updates need to be written in data blocks consisting of multiple data bytes. An Ra table update requires erasing a single page of DF, programming the updated Ra table and a flag. The potential I2C clock stretching time is 24 ms maximum. This includes 20-ms page erase and 2-ms row programming time (×2 rows). The Ra table updates occur during the discharge cycle and at up to 15 resistance grid points that occur during the discharge cycle. A DF block write typically requires a maximum of 72 ms. This includes copying data to a temporary buffer and updating DF. This temporary buffer mechanism is used to protect from power failure during a DF update. The first part of the update requires 20 ms to erase the copy buffer page, 6 ms to write the data into the copy buffer and the program progress indicator (2 ms for each individual write). The second part of the update is writing to the DF and requires 44 ms for DF block update. This includes a 20-ms each page erase for two pages and 2-ms each row write for two rows. In the event that a previous DF write was interrupted by a power failure or reset during the DF write, an additional 44-ms maximum DF restore time is required to recover the data from a previously interrupted DF write. In this power failure recovery case, the total I2C clock stretching is 116 ms maximum. Another case where I2C clock stretches is at the end of discharge. The update to the last discharge data will go through the DF block update twice because two pages are used for the data storage. The clock stretching in this case is 144 ms maximum. This occurs if there has been a Ra table update during the discharge. 28 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.6 Programming 8.6.1 Standard Data Commands The fuel gauge uses a series of 2-byte standard commands to enable system reading and writing of battery information. Each standard command has an associated command-code pair, as indicated in Table 14. Each protocol has specific means to access the data at each Command Code. DataRAM is updated and read by the gauge only once per second. Standard commands are accessible in NORMAL operation mode. Table 14. Standard Commands NAME COMMAND CODE UNIT SEALED ACCESS Control( ) CNTL 0x00 and 0x01 NA RW AtRate( ) AR 0x02 and 0x03 mA RW UnfilteredSOC() UFSOC 0x04 and 0x05 % R Temperature( ) TEMP 0x06 and 0x07 0.1°K R Voltage( ) VOLT 0x08 and 0x09 mV R Flags( ) FLAGS 0x0A and 0x0B NA R NomAvailableCapacity( ) NAC 0x0C and 0x0D mAh R FullAvailableCapacity( ) FAC 0x0E and 0x0F mAh R RemainingCapacity( ) RM 0x10 and 0x11 mAh R FullChargeCapacity( ) FCC 0x12 and 0x13 mAh R AI 0x14 and 0x15 mA R TTE 0x16 and 0x17 Minutes R FFCC 0x18 and 0x19 mAh R SI 0x1A and 0x1B mA R UFFCC 0x1C and 0x1D mAh R AverageCurrent( ) TimeToEmpty( ) FilteredFCC() StandbyCurrent( ) UnfilteredFCC() MaxLoadCurrent( ) UnfilteredRM() FilteredRM() AveragePower( ) MLI 0x1E and 0x1F mA R UFRM 0x20 and 0x21 mAh R FRM 0x22 and 0x23 mAh R AP 0x24 and 0x25 mW or cW R INTTEMP 0x28 and 0x29 0.1°K R CC 0x2A and 0x2B Counts R SOC 0x2C and 0x2D % R StateOfHealth( ) SOH 0x2E and 0x2F % / num R PassedCharge( ) PCHG 0x34 and 0x35 mAh R DOD0( ) DOD0 0x36 and 0x37 Hex R SelfDischargeCurrent() SDSG 0x38 and 0x39 mA R InternalTemperature( ) CycleCount( ) StateOfCharge( ) Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 29 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.6.1.1 Control( ): 0x00 and 0x01 Issuing a Control( ) command requires a subsequent 2-byte subcommand. These additional bytes specify the particular control function desired. The Control( ) command allows the system to control specific features of the fuel gauge during normal operation and additional features when the fuel gauge is in different access modes, as described in Table 15. Table 15. Control( ) Subcommands CNTL DATA SEALED ACCESS CONTROL_STATUS 0x0000 Yes Reports the status of DF Checksum, Hibernate, IT, etc. DEVICE_TYPE 0x0001 Yes Reports the device type of 0x0541 (indicating bq27541-G1) FW_VERSION 0x0002 Yes Reports the firmware version on the device type HW_VERSION 0x0003 Yes Reports the hardware version of the device type Reserved 0x0004 No Not to be used RESET_DATA 0x0005 Yes Returns reset data Reserved 0x0006 No Not to be used PREV_MACWRITE 0x0007 Yes Returns previous Control() subcommand code CHEM_ID 0x0008 Yes Reports the chemical identifier of the Impedance Track™ configuration BOARD_OFFSET 0x0009 No Forces the device to measure and store the board offset CC_OFFSET 0x000A No Forces the device to measure internal CC offset CNTL FUNCTION DESCRIPTION CC_OFFSET_SAVE 0x000B No Forces the device to store the internal CC offset DF_VERSION 0x000C Yes Reports the data flash version on the device SET_FULLSLEEP 0x0010 Yes Set the [FULLSLEEP] bit in Control Status register to 1 SET_HIBERNATE 0x0011 Yes Forces CONTROL_STATUS [HIBERNATE] to 1 CLEAR_HIBERNATE 0x0012 Yes Forces CONTROL_STATUS [HIBERNATE] to 0 SET_SHUTDOWN 0x0013 Yes Enables the SE pin to change state CLEAR_SHUTDOWN 0x0014 Yes Disables the SE pin from changing state SET_HDQINTEN 0x0015 Yes Forces CONTROL_STATUS [HDQIntEn] to 1 CLEAR_HDQINTEN 0x0016 Yes Forces CONTROL_STATUS [HDQIntEn] to 0 STATIC_CHEM_CHKSUM 0x0017 Yes Calculates chemistry checksum SEALED 0x0020 No Places the bq27541-G1 in SEALED access mode IT_ENABLE 0x0021 No Enables the Impedance Track™ algorithm CAL_ENABLE 0x002D No Toggle bq27541-G1 calibration mode RESET 0x0041 No Forces a full reset of the bq27541-G1 EXIT_CAL 0x0080 No Exit bq27541-G1 calibration mode ENTER_CAL 0x0081 No Enter bq27541-G1 calibration mode OFFSET_CAL 0x0082 No Reports internal CC offset in calibration mode 30 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.6.1.1.1 CONTROL_STATUS: 0x0000 Instructs the fuel gauge to return status information to Control( ) addresses 0x00 and 0x01. The status word includes the following information. Table 16. CONTROL_STATUS Flags bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 High Byte SE FAS SS CALMODE CCA BCA RSVD HDQHOSTIN Low Byte SHUTDWN HIBERNATE FULLSLEEP SLEEP LDMD RUP_DIS VOK QEN SE = Status bit indicating the SE pin is active. True when set. Default is 0. FAS = Status bit indicating the bq27541-G1 is in FULL ACCESS SEALED state. Active when set. SS = Status bit indicating the bq27541-G1 is in the SEALED State. Active when set. CALMODE = Status bit indicating the calibration function is active. True when set. Default is 0. CCA = Status bit indicating the bq27541-G1 Coulomb Counter Calibration routine is active. The CCA routine will take place approximately 1 minute after the initialization and periodically as gauging conditions change. Active when set. BCA = Status bit indicating the bq27541-G1 Board Calibration routine is active. Active when set. RSVD = Reserved. HDQHOSTIN = Status bit indicating the HDQ interrupt function is active. True when set. Default is 0. SHUTDWN = Control bit indicating that the SET_SHUTDOWN command has been sent and the state of the SE pin can change to signal an external shutdown of the fuel gauge when conditions permit. See the Shutdown Mode section. HIBERNATE = Status bit indicating a request for entry into HIBERNATE from SLEEP mode has been issued. True when set. Default is 0. FULLSLEEP = Status bit indicating the bq27541-G1 is in FULLSLEEP mode. True when set. The state can be detected by monitoring the power used by the bq27541-G1 because any communication will automatically clear it. SLEEP = Status bit indicating the bq27541-G1 is in SLEEP mode. True when set. LDMD = Status bit indicating the bq27541-G1 Impedance Track™ algorithm is using constant-power mode. True when set. Default is 0 (constant-current mode). RUP_DIS = Status bit indicating the bq27541-G1 Ra table updates are disabled. True when set. VOK = Status bit indicating cell voltages are OK for Qmax updates. True when set. QEN = Status bit indicating the bq27541-G1 Qmax updates are enabled. True when set. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 31 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.6.1.1.2 DEVICE_TYPE: 0x0001 Instructs the fuel gauge to return the device type to addresses 0x00 and 0x01. The bq27541-G1 device type returns 0x0541. 8.6.1.1.3 FW_VERSION: 0x0002 Instructs the fuel gauge to return the firmware version to addresses 0x00 and 0x01. The bq27541-G1 firmware version returns 0x0224. 8.6.1.1.4 HW_VERSION: 0x0003 Instructs the fuel gauge to return the hardware version to addresses 0x00 and 0x01. For bq27541-G1, 0x0000 or 0x0060 is returned. 8.6.1.1.5 RESET_DATA: 0x0005 Instructs the fuel gauge to return the number of resets performed to addresses 0x00 and 0x01. 8.6.1.1.6 PREV_MACWRITE: 0x0007 Instructs the fuel gauge to return the previous Control() subcommand written to addresses 0x00 and 0x01. The value returned is limited to less than 0x0020. 8.6.1.1.7 CHEM_ID: 0x0008 Instructs the fuel gauge to return the chemical identifier for the Impedance Track™ configuration to addresses 0x00 and 0x01. 8.6.1.1.8 BOARD_OFFSET: 0x0009 Instructs the fuel gauge to perform board offset calibration. During board offset calibration the [BCA] bit is set. 8.6.1.1.9 CC_OFFSET: 0x000A Instructs the fuel gauge to perform coulomb counter offset calibration. During calibration the [CCA] bit is set. 8.6.1.1.10 CC_OFFSET_SAVE: 0x000B Instructs the fuel gauge to save calibration coulomb counter offset after calibration. 8.6.1.1.11 DF_VERSION: 0x000C Instructs the gas gauge to return the data flash version stored in DF Config Version to addresses 0x00 and 0x01. 8.6.1.1.12 SET_FULLSLEEP: 0x0010 Instructs the gas gauge to set the [FULLSLEEP] bit in Control Status register to 1. This will allow the gauge to enter the FULLSLEEP power mode after the transition to SLEEP power state is detected. In FULLSLEEP mode less power is consumed by disabling an oscillator circuit used by the communication engines. For HDQ communication one host message will be dropped. For I2C communications the first I2C message will incur a 6to 8-ms clock stretch while the oscillator is started and stabilized. A communication to the device in FULLSLEEP will force the part back to the SLEEP mode. 8.6.1.1.13 SET_HIBERNATE: 0x0011 Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 1. This will allow the gauge to enter the HIBERNATE power mode after the transition to SLEEP power state is detected and the required conditions are met. The [HIBERNATE] bit is automatically cleared upon exiting from HIBERNATE mode. NOTE Note: The HIBERNATE mode is only available in I2C mode and is disabled when HDQ mode is used. 32 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.6.1.1.14 CLEAR_HIBERNATE: 0x0012 Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 0. This will prevent the gauge from entering the HIBERNATE power mode after the transition to SLEEP power state is detected unless Voltage() is less than Hibernate V. It can also be used to force the gauge out of HIBERNATE mode. 8.6.1.1.15 SET_SHUTDOWN: 0x0013 Sets the CONTROL_STATUS [SHUTDWN] bit to 1, thereby enabling the SE pin to change state. The Impedance Track™ algorithm controls the setting of the SE pin, depending on whether the conditions are met for fuel gauge shutdown or not. 8.6.1.1.16 CLEAR_SHUTDOWN: 0x0014 Disables the SE pin from changing state. The SE pin is left in a high-impedance state. 8.6.1.1.17 SET_HDQINTEN: 0x0015 Instructs the fuel gauge to set the CONTROL_STATUS [HDQIntEn] bit to 1. This enables the HDQ Interrupt function. When this subcommand is received, the device will detect any of the interrupt conditions and assert the interrupt at one second intervals until the CLEAR_HDQINTEN command is received or the count of HDQHostIntrTries has lapsed (default 3). 8.6.1.1.18 CLEAR_HDQINTEN: 0x0016 Instructs the fuel gauge to set the CONTROL_STATUS [HDQIntEn] bit to 0. This disables the HDQ Interrupt function. 8.6.1.1.19 STATIC_CHEM_DF_CHKSUM: 0x0017 Instructs the fuel gauge to calculate chemistry checksum as a 16-bit unsigned integer sum of all static chemistry data. The most significant bit (MSB) of the checksum is masked yielding a 15-bit checksum. This checksum is compared with value stored in the data flash Static Chem DF Checksum. If the value matches, the MSB is cleared to indicate pass. If it does not match, the MSB is set to indicate failure. The checksum can be used to verify the integrity of the chemistry data stored internally. 8.6.1.1.20 SEALED: 0x0020 Instructs the gas gauge to transition from UNSEALED state to SEALED state. The gas gauge should always be set to SEALED state for use in customer’s end equipment as it prevents spurious writes to most Standard Commands and blocks access to most data flash. 8.6.1.1.21 IT ENABLE: 0x0021 This command forces the fuel gauge to begin the Impedance Track™ algorithm, sets bit 2 of UpdateStatus and causes the [VOK] and [QEN] flags to be set in the CONTROL_STATUS register. [VOK] is cleared if the voltages are not suitable for a Qmax update. Once set, [QEN] cannot be cleared. This command is only available when the fuel gauge is UNSEALED and is typically enabled at the last step of production after system test is completed. 8.6.1.1.22 RESET: 0x0041 This command instructs the gas gauge to perform a full reset. This command is only available when the gas gauge is UNSEALED. 8.6.1.1.23 EXIT_CAL: 0x0080 This command instructs the gas gauge to exit calibration mode. 8.6.1.1.24 ENTER_CAL: 0x0081 This command instructs the gas gauge to enter calibration mode. 8.6.1.1.25 OFFSET_CAL: 0x0082 This command instructs the gas gauge to perform offset calibration. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 33 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.6.1.2 AtRate( ): 0x02 and 0x03 The AtRate( ) read- or write-word function is the first half of a two-function command call-set used to set the AtRate value used in calculations made by the AtRateTimeToEmpty( ) function. The AtRate( ) units are in mA. The AtRate( ) value is a signed integer, with negative values interpreted as a discharge current value. The AtRateTimeToEmpty( ) function returns the predicted operating time at the AtRate value of discharge. The default value for AtRate( ) is zero and will force AtRateTimeToEmpty( ) to return 65,535. Both the AtRate( ) and AtRateTimeToEmpty( ) commands should only be used in NORMAL mode. 8.6.1.3 UnfilteredSOC( ): 0x04 and 0x05 This read-only function returns an unsigned integer value of the predicted remaining battery capacity expressed as a percentage of UnfilteredFCC(), with a range of 0 to 100%. 8.6.1.4 Temperature( ): 0x06 and 0x07 This read-only function returns an unsigned integer value of the battery temperature in units of 0.1°K measured by the fuel gauge and is used for fuel gauging algorithm. It reports either the InternalTemperature() or the external thermistor temperature depending on the setting of [TEMPS] bit in Pack Configuration. 8.6.1.5 Voltage( ): 0x08 and 0x09 This read-only function returns an unsigned integer value of the measured cell-pack voltage in mV with a range of 0 to 6000 mV. 8.6.1.6 Flags( ): 0x0A and 0x0B This read-only function returns the contents of the gas-gauge status register, depicting the current operating status. Table 17. Flags Bit Definitions bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 High Byte OTC OTD BATHI BATLOW CHG_INH Low Byte OCVTAKEN ISD TDD HW1 HW0 RSVD FC CHG SOC1 SOCF DSG High Byte OTC = Over-Temperature in Charge condition is detected. True when set. Refer to the Data Flash Safety Subclass parameters for threshold settings. OTD = Over-Temperature in Discharge condition is detected. True when set. Refer to the Data Flash Safety Subclass parameters for threshold settings. BATHI = BATLOW = Battery High bit indicating a high battery voltage condition. Refer to the Data Flash BATTERY HIGH parameters for threshold settings. Battery Low bit indicating a low battery voltage condition. Refer to the Data Flash BATTERY LOW parameters for threshold settings. CHG_INH = Charge Inhibit indicates the temperature is outside the range [Charge Inhibit Temp Low, Charge Inhibit Temp High]. True when set. RSVD = Reserved. Full-charged is detected. FC is set when charge termination is reached and FC Set% = -1 (see the Charging and FC = Charge Termination Indication section for details) or State of Charge is larger than FC Set% and FC Set% is not –1. True when set. CHG = (Fast) charging allowed. True when set. Low Byte OCVTAKEN = Cleared on entry to relax mode and set to 1 when OCV measurement is performed in relax. ISD = Internal Short is detected. True when set. TDD = Tab Disconnect is detected. True when set. HW[1:0] = Device Identification. Default is 01 SOC1 = State-of-Charge-Threshold 1 is detected. SOC1 bit is set when State of Charge reaches below SOC1 Set Threshold. SOC1 bit clears when State-of-Charge gets above SOC1 Clear Threshold. True when set. 34 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 SOCF = State-of-Charge-Threshold Final is detected. SOCF bit is set when State of Charge reaches below SOCF Set Threshold. SOCF bit clears when State-of-Charge gets above SOCF Clear Threshold. True when set. DSG = Discharging detected. True when set. 8.6.1.7 NominalAvailableCapacity( ): 0x0C and 0x0D This read-only command pair returns the uncompensated (less than C/20 load) battery capacity remaining. Units are mAh. 8.6.1.8 FullAvailableCapacity( ): 0x0E and 0x0F This read-only command pair returns the uncompensated (less than C/20 load) capacity of the battery when fully charged. Units are mAh. FullAvailableCapacity( ) is updated at regular intervals, as specified by the IT algorithm. 8.6.1.9 RemainingCapacity( ): 0x10 and 0x11 This read-only command pair returns the compensated battery capacity remaining (UnfilteredRM()) when the [SmoothEn] bit in Operating Configuration C is cleared or filtered compensated battery capacity remaining (FilteredRM()) when [SmoothEn] is set. Units are mAh. 8.6.1.10 FullChargeCapacity( ): 0x12 and 0x13 This read-only command pair returns the compensated capacity of fully charged battery (UnfilteredFCC()) when the [SmoothEn] bit in Operating Configuration C is cleared or filtered compensated capacity of fully charged battery (FilteredFCC()) when [SmoothEn] is set. Units are mAh. FullChargeCapacity() is updated at regular intervals, as specified by the IT algorithm. 8.6.1.11 AverageCurrent( ): 0x14 and 0x15 This read-only command pair returns a signed integer value that is the average current flow through the sense resistor. It is updated every 1 second. Units are mA. 8.6.1.12 TimeToEmpty( ): 0x16 and 0x17 This read-only function returns an unsigned integer value of the predicted remaining battery life at the present rate of discharge, in minutes. A value of 65,535 indicates battery is not being discharged. 8.6.1.13 FilteredFCC( ): 0x18 and 0x19 This read-only command pair returns the filtered compensated capacity of the battery when fully charged when the [SmoothEn] bit in Operating Configuration C is set. Units are mAh. FilteredFCC() is updated at regular intervals, as specified by the IT algorithm. 8.6.1.14 StandbyCurrent( ): 0x1A and 0x1B This read-only function returns a signed integer value of the measured system standby current through the sense resistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby current programmed in Initial Standby, and after spending some time in standby, reports the measured standby current. The register value is updated every 1 second when the measured current is above the Deadband and is less than or equal to 2 × Initial Standby. The first and last values that meet this criteria are not averaged in, since they may not be stable values. To approximate a 1-minute time constant, each new StandbyCurrent( ) value is computed by taking approximate 93% weight of the last standby current and approximate 7% of the current measured average current. 8.6.1.15 UnfilteredFCC( ): 0x1C and 0x1D This read-only command pair returns the compensated capacity of the battery when fully charged. Units are mAh. UnFilteredFCC() is updated at regular intervals, as specified by the IT algorithm. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 35 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.6.1.16 MaxLoadCurrent( ): 0x1E and 0x1F This read-only function returns a signed integer value, in units of mA, of the maximum load conditions of the system. The MaxLoadCurrent( ) is an adaptive measurement which is initially reported as the maximum load current programmed in Initial Max Load Current. If the measured current is ever greater than Initial Max Load Current, then MaxLoadCurrent( ) updates to the new current. MaxLoadCurrent( ) is reduced to the average of the previous value and Initial Max Load Current whenever the battery is charged to full after a previous discharge to an SOC less than 50%. This prevents the reported value from maintaining an unusually high value. 8.6.1.17 UnfilteredRM( ): 0x20 and 0x21 This read-only command pair returns the compensated battery capacity remaining. Units are mAh. 8.6.1.18 FilteredRM( ): 0x22 and 0x23 This read-only command pair returns the filtered compensated battery capacity remaining when [SmoothEn] bit in Operating Configuration C is set. Units are mAh. 8.6.1.19 AveragePower( ): 0x24 and 0x25 This read-word function returns an unsigned integer value of the average power of the current discharge. It is negative during discharge and positive during charge. A value of 0 indicates that the battery is not being discharged. The value is reported in units of mW (Design Energy Scale = 1) or cW (Design Energy Scale = 10). 8.6.1.20 InternalTemperature( ): 0x28 and 0x29 This read-only function returns an unsigned integer value of the measured internal temperature of the device in units of 0.1°K measured by the fuel gauge. 8.6.1.21 CycleCount( ): 0x2A and 0x2B This read-only function returns an unsigned integer value of the number of cycles the battery has experienced with a range of 0 to 65,535. One cycle occurs when accumulated discharge ≥ CC Threshold. 8.6.1.22 StateOfCharge( ): 0x2C and 0x2D This read-only function returns an unsigned integer value of the predicted RemainingCapacity() expressed as a percentage of FullChargeCapacity( ), with a range of 0 to 100%. The StateOfCharge() can be filtered or unfiltered since RemainingCapacity() and FullChargeCapacity( ) can be filtered or unfiltered based on [SmoothEn] bit selection. 8.6.1.23 StateOfHealth( ): 0x2E and 0x2F 0x2E SOH percentage: this read-only function returns an unsigned integer value, expressed as a percentage of the ratio of predicted FCC(25°C, SOH Load I) over the DesignCapacity(). The FCC(25°C, SOH Load I) is the calculated full charge capacity at 25°C and the SOH current rate which is specified by SOH Load I. The range of the returned SOH percentage is 0x00 to 0x64, indicating 0 to 100% correspondingly. 8.6.1.24 PassedCharge( ): 0x34 and 0x35 This signed integer indicates the amount of charge passed through the sense resistor since the last IT simulation in mAh. 8.6.1.25 DOD0( ): 0x36 and 0x37 This unsigned integer indicates the depth of discharge during the most recent OCV reading. 8.6.1.26 SelfDischargeCurrent( ): 0x38 and 0x39 This read-only command pair returns the signed integer value that estimates the battery self-discharge current. 36 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 8.6.2 Extended Data Commands Extended commands offer additional functionality beyond the standard set of commands. They are used in the same manner; however unlike standard commands, extended commands are not limited to 2-byte words. The number of command bytes for a given extended command ranges in size from single to multiple bytes, as specified in Table 18. For details on the SEALED and UNSEALED states, see Access Modes. Table 18. Extended Commands NAME COMMAND CODE Reserved UNIT SEALED ACCESS (1) (2) UNSEALED ACCESS (1) (2) RSVD 0x38 and 0x39 NA R R PCR 0x3A and 0x3B Hex# R R DCAP 0x3C and 0x3D mAh R R DataFlashClass( ) (2) DFCLS 0x3E NA NA RW DataFlashBlock( ) (2) DFBLK 0x3F NA RW RW A/DF 0x40 through 0x53 NA RW RW ACKS/DFD 0x54 NA RW RW PackConfig( ) DesignCapacity( ) BlockData( ) / Authenticate( ) (3) BlockData( ) / AuthenticateCheckSum( ) (3) BlockData( ) DFD 0x55 through 0x5F NA R RW BlockDataCheckSum( ) DFDCKS 0x60 NA RW RW BlockDataControl( ) DFDCNTL 0x61 NA NA RW DeviceNameLength( ) DeviceName( ) DNAMELEN 0x62 NA R R DNAME 0x63 through 0x6C NA R R RSVD 0x6D through 0x7F NA R R Reserved (1) (2) (3) SEALED and UNSEALED states are entered via commands to Control( ) 0x00 and 0x01. In SEALED mode, data flash cannot be accessed through commands 0x3E and 0x3F. The BlockData( ) command area shares functionality for accessing general data flash and for using Authentication. See Authentication for more details. 8.6.2.1 PackConfig( ): 0x3A and 0x3B SEALED and UNSEALED Access: This command returns the value stored in Pack Configuration and is expressed in hex value. 8.6.2.2 DesignCapacity( ): 0x3C and 0x3D SEALED and UNSEALED Access: This command returns the value stored in Design Capacity and is expressed in mAh. This is intended to be the theoretical or nominal capacity of a new pack, but has no bearing on the operation of the fuel gauge functionality. 8.6.2.3 DataFlashClass( ): 0x3E This command sets the data flash class to be accessed. The subclass ID to be accessed should be entered in hexadecimal. SEALED Access: This command is not available in SEALED mode. 8.6.2.4 DataFlashBlock( ): 0x3F UNSEALED Access: This command sets the data flash block to be accessed. When 0x00 is written to BlockDataControl( ), DataFlashBlock( ) holds the block number of the data flash to be read or written. Example: writing a 0x00 to DataFlashBlock( ) specifies access to the first 32-byte block and a 0x01 specifies access to the second 32-byte block, and so on. SEALED Access: This command directs which data flash block is accessed by the BlockData( ) command. Writing a 0x00 to DataFlashBlock( ) specifies the BlockData( ) command transfers authentication data. Issuing a 0x01 or 0x02 instructs the BlockData( ) command to transfer Manufacturer Info Block A or B, respectively. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 37 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 8.6.2.5 BlockData( ): 0x40 Through 0x5F This command range is used to transfer data for data flash class access. This command range is the 32-byte data block used to access Manufacturer Info Block A or B. Manufacturer Info Block A is read only for the sealed access. UNSEALED access is read/write. 8.6.2.6 BlockDataChecksum( ): 0x60 The host system should write this value to inform the device that new data is ready for programming into the specified data flash class and block. UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read or written to data flash. The least-significant byte of the sum of the data bytes written must be complemented ( [255 – x] , for x the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis.) before being written to 0x60. SEALED Access: This byte contains the checksum for the 32 bytes of block data written to Manufacturer Info Block A. The least-significant byte of the sum of the data bytes written must be complemented ( [255 – x] , for x the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis.) before being written to 0x60. 8.6.2.7 BlockDataControl( ): 0x61 UNSEALED Access: This command is used to control data flash access mode. The value determines the data flash to be accessed. Writing 0x00 to this command enables BlockData( ) to access general data flash. SEALED Access: This command is not available in SEALED mode. 8.6.2.8 DeviceNameLength( ): 0x62 UNSEALED and SEALED Access: This byte contains the length of the Device Name. 8.6.2.9 DeviceName( ): 0x63 Through 0x6C UNSEALED and SEALED Access: This block contains the device name that is programmed in Device Name. 8.6.2.10 Reserved – 0x6A Through 0x7F 38 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 9 Data Flash Interface 9.1 Accessing the Data Flash The data flash is a non-volatile memory that contains initialization, default, cell status, calibration, configuration, and user information. The data flash can be accessed in several different ways, depending on what mode the fuel gauge is operating in and what data is being accessed. Commonly accessed data flash memory locations, frequently read by a system, are conveniently accessed through specific instructions, already described in Data Commands. These commands are available when the fuel gauge is either in UNSEALED or SEALED modes. Most data flash locations, however, are only accessible in UNSEALED mode by use of the evaluation software or by data flash block transfers. These locations should be optimized and/or fixed during the development and manufacture processes. They become part of a golden image file and can then be written to multiple battery packs. Once established, the values generally remain unchanged during end-equipment operation. To access data flash locations individually, the block containing the desired data flash location(s) must be transferred to the command register locations, where they can be read to the system or changed directly. This is accomplished by sending the set-up command BlockDataControl( ) (0x61) with data 0x00. Up to 32 bytes of data can be read directly from the BlockData( ) (0x40 through 0x5F), externally altered, then rewritten to the BlockData( ) command space. Alternatively, specific locations can be read, altered, and rewritten if their corresponding offsets are used to index into the BlockData( ) command space. Finally, the data residing in the command space is transferred to data flash, once the correct checksum for the whole block is written to BlockDataChecksum( ) (0x60). Occasionally, a data flash Class will be larger than the 32-byte block size. In this case, the DataFlashBlock( ) command is used to designate which 32-byte block the desired locations reside in. The correct command address is then given by 0x40 + offset modulo 32. For example, to access Terminate Voltage in the Gas Gauging class, DataFlashClass( ) is issued 80 (0x50) to set the class. Because the offset is 67, it must reside in the third 32-byte block. Hence, DataFlashBlock( ) is issued 0x02 to set the block offset, and the offset used to index into the BlockData( ) memory area is 0x40 + 67 modulo 32 = 0x40 + 16 = 0x40 + 0x03 = 0x43. Reading and writing subclass data are block operations up to 32 bytes in length. If during a write the data length exceeds the maximum block size, then the data is ignored. None of the data written to memory are bounded by the fuel gauge — the values are not rejected by the fuel gauge. Writing an incorrect value may result in hardware failure due to firmware program interpretation of the invalid data. The written data is persistent, so a power-on reset does not resolve the fault. 9.2 Manufacturer Information Blocks The fuel gauge contains 64 bytes of user programmable data flash storage: Manufacturer Info Block A and Manufacturer Info Block B. The method for accessing these memory locations is slightly different, depending on whether the device is in UNSEALED or SEALED modes. When in UNSEALED mode and when 0x00 has been written to BlockDataControl( ), accessing the Manufacturer Info Blocks is identical to accessing general data flash locations. First, a DataFlashClass( ) command is used to set the subclass, then a DataFlashBlock( ) command sets the offset for the first data flash address within the subclass. The BlockData( ) command codes contain the referenced data flash data. When writing the data flash, a checksum is expected to be received by BlockDataChecksum( ). Only when the checksum is received and verified is the data actually written to data flash. As an example, the data flash location for Manufacturer Info Block B is defined as having a Subclass = 58 and an Offset = 32 through 63 (32-byte block). The specification of Class = System Data is not needed to address Manufacturer Info Block B, but is used instead for grouping purposes when viewing data flash info in the evaluation software. When in SEALED mode or when 0x01 BlockDataControl( ) does not contain 0x00, data flash is no longer available in the manner used in UNSEALED mode. Rather than issuing subclass information, a designated Manufacturer Information Block is selected with the DataFlashBlock( ) command. Issuing a 0x01 or 0x02 with this command causes the corresponding information block (A or B respectively) to be transferred to the command space 0x40 through 0x5F for editing or reading by the system. Upon successful writing of checksum information to BlockDataChecksum( ), the modified block is returned to data flash. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 39 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Manufacturer Information Blocks (continued) NOTE Manufacturer Info Block A is read-only when in SEALED mode. 9.3 Access Modes The bq27541-G1 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that control data flash access permissions according to Table 19. Data Flash refers to those data flash locations, Table 20 through Table 26, that are accessible to the user. Manufacture Information refers to the two 32-byte blocks. Table 19. Data Flash Access SECURITY MODE DATA FLASH MANUFACTURER INFORMATION FULL ACCESS RW RW UNSEALED RW RW SEALED None R (A); RW (B) Although FULL ACCESS and UNSEALED modes appear identical, only FULL ACCESS mode allows the fuel gauge to write access-mode transition keys stored in the Security class. 9.4 SEALING or UNSEALING Data Flash The fuel gauge implements a key-access scheme to transition between SEALED, UNSEALED, and FULLACCESS modes. Each transition requires that a unique set of two keys be sent to the fuel gauge via the Control( ) control command. The keys must be sent consecutively, with no other data being written to the Control( ) register in between. Note that to avoid conflict, the keys must be different from the codes presented in the CNTL DATA column of Table 15 subcommands. When in SEALED mode the [SS] bit of CONTROL_STATUS is set, but when the UNSEAL keys are correctly received by the fuel gauge, the [SS] bit is cleared. When the full-access keys are correctly received the CONTROL_STATUS [FAS] bit is cleared. Both Unseal Key and Full-Access Key have two words and are stored in data flash. The first word is Key 0 and the second word is Key 1. The order of the keys sent to fuel gauge are Key 1 followed by Key 0. The order of the bytes for each key entered through the Control( ) command is the reverse of what is read from the part. For an example, if the Unseal Key is 0x56781234, key 1 is 0x1234 and key 0 is 0x5678. Then Control( ) should supply 0x3412 and 0x7856 to unseal the part. The Unseal Key and the Full-Access Key can only be updated when in FULL-ACCESS mode. 40 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 9.5 Data Flash Summary Table 20 through Table 26 summarize the data flash locations available to the user, including their default, minimum, and maximum values. Table 20. Data Flash Summary—Configuration Class SUBCLASS ID 2 32 SUBCLASS Safety Charge Inhibit Cfg OFFSET NAME DATA TYPE VALUE MIN MAX DEFAULT UNIT (EVSW UNIT)* 0 OT Chg I2 0 1200 550 0.1°C 2 OT Chg Time U1 0 60 2 s 3 OT Chg Recovery I2 0 1200 500 0.1°C 5 OT Dsg I2 0 1200 600 0.1°C 7 OT Dsg Time U1 0 60 2 s 8 OT Dsg Recovery I2 0 1200 550 0.1°C 0 Chg Inhibit Temp Low I2 –400 1200 0 0.1°C 2 Chg Inhibit Temp High I2 –400 1200 450 0.1°C 4 Temp Hys I2 0 100 50 0.1°C mV 34 Charge 0 Charging Voltage I2 0 4600 4200 36 Charge Termination 0 Taper Current I2 0 1000 100 mA 2 Min Taper Capacity I2 0 1000 25 mAh 4 Taper Voltage I2 0 1000 100 mV 6 Current Taper Window U1 0 60 40 s 7 TCA Set % I1 –1 100 99 % 8 TCA Clear % I1 –1 100 95 % 9 FC Set % I1 –1 100 –1 % 10 FC Clear % I1 –1 100 98 % 11 DODatEOC Delta T I2 0 1000 50 0.1°C 0 Rem Cap Alarm I2 0 700 100 mA 8 Initial Standby I1 –256 0 –10 mA 9 Initial MaxLoad I2 –32767 0 –500 mA 17 Cycle Count U2 0 65535 0 19 CC Threshold I2 100 32767 900 mAh 23 Design Capacity I2 0 32767 1000 mAh 25 Design Energy I2 0 32767 5400 mWh 27 SOH Load I I2 –32767 0 –400 mA 29 TDD SOH Percent I1 0 100 80 % 40 ISD Current I2 0 32767 10 Hour Rate 48 Data 42 ISD I Filter U1 0 255 127 43 Min ISD Time U1 0 255 7 44 Design Energy Scale U1 0 255 1 45 Device Name S11 x x bq2754X-G1 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 Hour - 41 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Data Flash Summary (continued) Table 20. Data Flash Summary—Configuration Class (continued) SUBCLASS ID 49 56 OFFSET Discharge Manufacturer Data NAME DATA TYPE VALUE MIN MAX DEFAULT UNIT (EVSW UNIT)* 0 SOC1 Set Threshold U2 0 65535 150 mAh 2 SOC1 Clear Threshold U2 0 65535 175 mAh 4 SOCF Set Threshold U2 0 65535 75 mAh 6 SOCF Clear Threshold U2 0 65535 100 mAh 9 BL Set Volt Threshold I2 0 16800 2500 mV 11 BL Set Volt Time U1 0 60 2 s 12 BL Clear Volt Threshold I2 0000 16800 2600 mV 14 BH Set Volt Threshold I2 0 16800 4500 mV 16 BH Volt Time U1 0 60 2 s 17 BH Clear Volt Threshold I2 0000 16800 4400 mV 0 Pack Lot Code H2 0x0 0xFFFF 0x0 - 2 PCB Lot Code H2 0x0 0xFFFF 0x0 - 4 Firmware Version H2 0x0 0xFFFF 0x0 - 6 Hardware Revision H2 0x0 0xFFFF 0x0 - 8 Cell Revision H2 0x0 0xFFFF 0x0 - 10 DF Config Version H2 0x0 0xFFFF 0x0 - 0x0 0x7FFF 0x0 57 Integrity Data 6 Static Chem DF Checksum H2 59 Lifetime Data 0 Lifetime Max Temp I2 0 1400 0 0.1°C 2 Lifetime Min Temp I2 –600 1400 500 0.1°C 4 Lifetime Max Pack Voltage I2 0 32767 2800 mV 6 Lifetime Min Pack Voltage I2 0 32767 4200 mV 8 Lifetime Max Chg Current I2 –32767 32767 0 mA 10 Lifetime Max Dsg Current I2 –32767 32767 0 mA 60 Lifetime Temp Samples 0 LT Flash Cnt U2 0 65535 0 64 Registers 0 Pack Configuration H2 0x0 0xFFFF 0x1177 2 Pack Configuration B H1 0x0 0xFF 0xA7 3 Pack Configuration C H1 0x0 0xFF 0x18 0 LT Temp Res U1 0 255 10 Num 1 LT V Res U1 0 255 25 Num 2 LT Cur Res U1 0 255 100 Num 3 LT Update Time U2 0 65535 60 Num 0 Flash Update OK Voltage I2 0 4200 2800 mV 2 Sleep Current I2 0 100 10 mA 11 Hibernate I U2 0 700 8 mA 13 Hibernate V U2 2400 3000 2550 mV 15 FS Wait U1 0 255 0 s 66 68 42 SUBCLASS Lifetime Resolution Power Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 Table 21. Data Flash Summary—System Data Class SUBCLASS ID 58 SUBCLASS Manufacturer Info OFFSET 0 through 31 NAME DATA TYPE VALUE MIN MAX DEFAULT UNIT (EVSW UNIT)* Block A 0 through 31 H1 0x0 0xFF 0x0 - 32 through 63 Block B 0 through 31 H1 0x0 0xFF 0x0 - UNIT (EVSW UNIT)* Table 22. Data Flash Summary—Gas (Fuel) Gauging Class SUBCLASS ID 80 81 SUBCLASS IT Cfg Current Thresholds OFFSET NAME VALUE DATA TYPE MIN MAX DEFAULT 0 Load Select U1 0 255 1 1 Load Mode U1 0 255 0 21 Max Res Factor U1 0 255 15 22 Min Res Factor U1 0 255 5 25 Ra Filter U2 0 1000 800 67 Terminate Voltage I2 2800 3700 3000 mV 69 Term V Delta I2 0 4200 200 mV 72 ResRelax Time U2 0 65534 500 s 76 User Rate-mA I2 2000 9000 0 mA 78 User Rate-Pwr I2 3000 14000 0 mW or cW 80 Reserve Cap-mAh I2 0 9000 0 mA 82 Reserve Energy I2 0 14000 0 mWh or cWh 86 Max Scale Back Grid U1 0 15 4 87 Max DeltaV U2 0 65535 200 89 Min DeltaV U2 0 65535 0 mV 91 Max Sim Rate U1 0 255 1 C/rate 92 Min Sim Rate U1 0 255 20 C/rate 93 Ra Max Delta U2 0 65535 43 mΩ 95 Qmax Max Delta % U1 0 100 5 mAh 96 DeltaV Max Delta U2 0 65535 10 mV 102 Fast Scale Start SOC U1 0 100 10 % 103 Charge Hys V Shift I2 0 2000 40 mV 0 Dsg Current Threshold I2 0 2000 60 mA 2 Chg Current Threshold I2 0 2000 75 mA 4 Quit Current I2 0 1000 40 mA 6 Dsg Relax Time U2 0 8191 60 s 8 Chg Relax Time U1 0 255 60 s 9 Quit Relax Time U1 0 63 1 s 10 Max IR Correct U2 0 1000 400 mV mV Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 43 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com Table 22. Data Flash Summary—Gas (Fuel) Gauging Class (continued) SUBCLASS ID 82 SUBCLASS OFFSET State NAME DATA TYPE VALUE MIN MAX DEFAULT UNIT (EVSW UNIT)* mAh 0 Qmax Cell 0 I2 0 32767 1000 2 Cycle Count U2 0 65535 0 4 Update Status H1 0x0 0x6 0x0 5 V at Chg Term I2 0 5000 4200 mV 7 Avg I Last Run I2 –32768 32767 –299 mA 9 Avg P Last Run I2 –32768 32767 –1131 mW 11 Delta Voltage I2 –32768 32767 2 mV 15 T Rise I2 0 32767 20 Num 17 T Time Constant I2 0 32767 1000 Num Table 23. Data Flash Summary—OCV Table Class SUBCLASS ID 83 SUBCLASS OFFSET OCV Table 0 NAME Chem ID DATA TYPE VALUE MIN MAX DEFAULT UNIT (EVSW UNIT)* H2 0x0 0xFFFF 0x0128 num MAX DEFAULT UNIT (EVSW UNIT)* Table 24. Data Flash Summary—Ra Table Class SUBCLASS ID 88 SUBCLASS OFFSET R_a0 0 2 through 31 89 R_a0x 0 2 through 31 VALUE DATA TYPE NAME MIN Cell0 R_a flag H2 0x0 0x0 0xFF55 - Cell0 R_a 0 through 14 I2 183 183 407 2–10Ω xCell0 R_a flag H2 0xFFFF 0xFFFF 0xFFFF - xCell0 R_a 0 through 14 I2 183 183 407 2–10Ω DEFAULT UNIT (EVSW UNIT)* Table 25. Data Flash Summary—Calibration Class SUBCLASS ID 104 107 44 SUBCLASS OFFSET Data Current NAME DATA TYPE VALUE MIN MAX 0 CC Gain F4 1.0e–1 4.0e+1 0.4768 4 CC Delta F4 2.9826e+4 1.193046e+6 567744.56 8 CC Offset I2 –32768 32767 –1200 mA 10 Board Offset I1 –128 127 0 µA 11 Int Temp Offset I1 –128 127 0 12 Ext Temp Offset I1 –128 127 0 13 Pack V Offset I1 –128 127 0 1 Deadband U1 0 255 5 Submit Documentation Feedback mA Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 Table 26. Data Flash Summary—Security Class SUBCLASS ID 112 SUBCLASS Codes OFFSET NAME VALUE DATA TYPE MIN MAX DEFAULT UNIT (EVSW UNIT)* - 0 Sealed to Unsealed H4 0x0 0xFFFF FFFF 0x3672 0414 4 Unsealed to Full H4 0x0 0xFFFF FFFF 0xFFFF FFFF - 8 Authen Key3 H4 0x0 0xFFFF FFFF 0x0123 4567 - 12 Authen Key2 H4 0x0 0xFFFF FFFF 0x89AB CDEF - 16 Authen Key1 H4 0x0 0xFFFF FFFF 0xFEDC BA98 - 20 Authen Key0 H4 0x0 0xFFFF FFFF 0x7654 3210 - Table 27. Data Flash to EVSW Conversion Class SubClass ID SubClass Offset Name Data Type Data Flash Default Data Flash Unit EVSW Default EVSW Unit Data Flash (DF) to EVSW Conversion Gas Gauging 80 IT Cfg 78 User Rate-Pwr I2 0 cW or 10W 0 mW or cW DF × 10 Gas Gauging 80 IT Cfg 82 Reserve Energy I2 0 cWh or 10cWh 0 mWh or cWh DF × 10 Calibration 104 Data 0 CC Gain F4 0.47095 Num 10.124 mΩ 4.768 / DF Calibration 104 Data 4 CC Delta F4 5.595e5 Num 10.147 mΩ 5677445 / DF Calibration 104 Data 8 CC Offset I2 –1200 Num –0.576 mV DF × 0.0048 Calibration 104 Data 10 Board Offset I1 0 Num 0 µV DF × 0.0075 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 45 bq27541-G1 SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 www.ti.com 10 Application and Implementation 10.1 Typical Applications J10 R20 4.7k MM3511 3 5 4 6 2 1 R7, R8, and R9 are optional pulldown resistors if pullup resistors are applied. 46 Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 bq27541-G1 www.ti.com SLUSAL6D – NOVEMBER 2011 – REVISED MAY 2014 11 Device and Documentation Support 11.1 Documentation Support 11.1.1 Related Documentation from Texas Instruments To obtain a copy of any of the following TI documents, call the Texas Instruments Literature Response Center at (800) 477-8924 or the Product Information Center (PIC) at (972) 644-5580. When ordering, identify this document by its title and literature number. Updated documents also can be obtained through the TI Web site at www.ti.com. 1. bq27541 EVM: Single Cell Impedance Track™ Technology User's Guide (SLUU273) 11.2 Trademarks Impedance Track is a trademark of Texas Instruments. 11.3 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.4 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms and definitions. 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Submit Documentation Feedback Copyright © 2011–2014, Texas Instruments Incorporated Product Folder Links: bq27541-G1 47 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) BQ27541DRZR-G1 ACTIVE SON DRZ 12 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 BQ 7541 BQ27541DRZT-G1 ACTIVE SON DRZ 12 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 BQ 7541 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of