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bq27220
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bq27220 Single-Cell CEDV Fuel Gauge
1 Features
3 Description
•
The Texas Instruments bq27220 battery fuel gauge is
a single-cell gauge that requires minimal userconfiguration and system microcontroller firmware
development, leading to quick system bring-up. The
bq27220 device uses the Compensated End-ofDischarge Voltage (CEDV) algorithm for fuel gauging,
and provides information such as remaining battery
capacity (mAh), state-of-charge (%), runtime-to-empty
(min), battery voltage (mV), temperature (°C), and
state-of-health (%).
1
•
•
•
Single-Cell Li-Ion Battery Fuel Gauge
– Resides in Pack or on System Board
– Supports Embedded or Removable Batteries
– Powers Directly from Battery with Integrated
LDO
– Supports a Low-Value (10-mΩ) External Sense
Resistor
Ultra-Low Power Consumption in NORMAL
(50 µA) and SLEEP (9 µA) Modes
Battery Fuel Gauging Based on Compensated
End-of-Discharge Voltage (CEDV) Technology
– Reports Remaining Capacity and State-ofCharge (SOC) with Smoothing Filter
– Adjusts Automatically for Battery Aging, SelfDischarge, Temperature, and Rate Changes
– Provides Battery State-of-Health (Aging)
Estimation
Microcontroller Peripheral Supports:
– 400-kHz I2C™ Serial Interface
– Configurable SOC Interrupt OR
Battery Low Digital Output Warning
– Internal Temperature Sensor OR
Host-Reported Temperature OR
External Thermistor
2 Applications
•
•
•
•
•
•
•
The bq27220 battery fuel gauge has ultra-low power
consumption in NORMAL (50 μA) and SLEEP (9 μA)
modes, leading to longer battery runtime.
Configurable interrupts help save system power and
free up the host from continuous polling. Accurate
temperature sensing is supported via an external
thermistor.
Customers can use preloaded CEDV parameters in
ROM or can generate custom chemistry parameters
using TI's web-based tool, GAUGEPARCAL. Customgenerated parameters can be either programmed in
the device RAM by the host on power up of the
system or customers can program the parameters to
an onboard One-Time Programmable (OTP) memory.
Battery fuel gauging with the bq27220 device requires
connections only to PACK+ (P+) and PACK– (P–) for
a removable battery pack or embedded battery
circuit. The tiny, 9-ball, 1.62 mm × 1.58 mm, 0.5-mm
pitch NanoFree™ chip scale package (DSBGA) is
ideal for space-constrained applications.
Smartphones and Feature Phones
Tablets
Wearables
Building Automation
Portable Medical/Industrial Handsets
Portable Audio
Gaming
Device Information(1)
PART NUMBER
bq27220
PACKAGE
YZF (9)
BODY SIZE (NOM)
1.62 mm × 1.58 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic (System-Side)
I 2C
Bus
SRN
SCL
Coulomb
Counter
SDA
VSYS
SRP
CPU
Battery Pack
GPOUT
ADC
BAT
PACKP
BIN
T
VDD
1.8 V
LDO
2.2 µF
VSS
1 µF
PACKN
Li-Ion
Cell
Protection
IC
NFET
NFET
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.
bq27220
SLUSCB7A – MARCH 2016 – REVISED APRIL 2016
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Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
6.13 Typical Characteristics ............................................ 8
1
1
1
2
3
4
7
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram (System-Side
Configuration)............................................................. 9
7.3 Feature Description................................................... 9
7.4 Device Functional Modes........................................ 11
6.1
6.2
6.3
6.4
6.5
6.6
6.7
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions....................... 5
Thermal Information .................................................. 5
Supply Current .......................................................... 5
Digital Input and Output DC Characteristics ............. 5
LDO Regulator, Wake-up, and Auto-Shutdown DC
Characteristics ........................................................... 6
6.8 LDO Regulator, Wake-up, and Auto-shutdown AC
Characteristics ........................................................... 6
6.9 ADC (Temperature and Cell Measurement)
Characteristics ........................................................... 6
6.10 Integrating ADC (Coulomb Counter) Characteristics
................................................................................... 6
6.11 I2C-Compatible Interface Communication Timing
Characteristics ........................................................... 7
6.12 SHUTDOWN and WAKE-UP Timing ...................... 8
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Applications ................................................ 12
9
Power Supply Recommendation ........................ 15
9.1 Power Supply Decoupling ....................................... 15
10 Layout................................................................... 15
10.1 Layout Guidelines ................................................. 15
10.2 Layout Example .................................................... 16
11 Device and Documentation Support ................. 17
11.1
11.2
11.3
11.4
11.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
17
17
17
17
17
12 Mechanical, Packaging, and Orderable
Information ........................................................... 17
4 Revision History
2
DATE
REVISION
NOTES
April 2016
A
PRODUCT PREVIEW to Production Data
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5 Pin Configuration and Functions
Top View
3
2
1
C
B
A
Bottom View
1
2
3
C
B
A
Pin Functions
PIN
NAME
BAT
BIN
(1)
NUMBER
C3
B1
TYPE
DESCRIPTION
PI, AI (1)
LDO regulator input and battery voltage measurement input. Kelvin sense connect to the positive
battery terminal (PACKP). Connect a capacitor (1 µF) between BAT and VSS. Place the capacitor
close to the gauge.
DI
Battery insertion detection input. If OpConfig [BI_PU_EN] = 1 (default), a logic low on the pin is
detected as battery insertion. For a removable pack, the BIN pin can be connected to VSS
through a pulldown resistor on the pack, typically the 10-kΩ thermistor; the system board should
use a 1.8-MΩ pullup resistor to VDD to ensure the BIN pin is high when a battery is removed. If
the battery is embedded in the system or in the pack, it is recommended to leave [BI_PU_EN] =
1 and use a 10-kΩ pulldown resistor from BIN to VSS. If [BI_PU_EN] = 0, then the host must
inform the gauge of battery insertion and removal with the BAT_INSERT and BAT_REMOVE
subcommands. A 10-kΩ pulldown resistor should be placed between BIN and VSS, even if this
pin is unused.
NOTE: The BIN pin must not be shorted directly to VCC or VSS and any pullup resistor on the BIN
pin must be connected only to VDD and not an external voltage rail. If an external thermistor is
used for temperature input, the thermistor should be connected between this pin and VSS.
IO = Digital input-output, AI = Analog input, P = Power connection
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Pin Functions (continued)
PIN
NAME
NUMBER
TYPE
DESCRIPTION
This open-drain output can be configured to indicate BAT_LOW when the OpConfig
[BATLOWEN] bit is set. By default [BATLOWEN] is cleared and this pin performs an interrupt
function (SOC_INT) by pulsing for specific events, such as a change in state-of-charge. Signal
polarity for these functions is controlled by the [GPIOPOL] configuration bit. This pin should not
be left floating, even if unused; therefore, a 10-kΩ pullup resistor is recommended. If the device
is in SHUTDOWN mode, toggling GPOUT makes the gauge exit SHUTDOWN. It is
recommended to connect GPOUT to a GPIO of the host MCU so that in case of any inadvertent
shutdown condition, the gauge can be commanded to come out of SHUTDOWN.
GPOUT
A1
DO
SCL
A3
DIO
SDA
A2
DIO
SRN
C2
AI
SRP
C1
AI
VDD
B3
PO
1.8-V regulator output. Decouple with a 2.2-μF ceramic capacitor to VSS. This pin is not intended
to provide power for other devices in the system.
VSS
B2
PI
Ground pin
Slave I2C serial bus for communication with system (Master). Open-drain pins. Use with external
10-kΩ pullup resistors (typical) for each pin. If the external pullup resistors will be disconnected
from these pins during normal operation, recommend using external 1-MΩ pulldown resistors to
VSS at each pin to avoid floating inputs.
Coulomb counter differential inputs expecting an external 10-mΩ, 1% sense resistor. For systemside configurations, Kelvin sense connect SRP to the positive battery terminal (PACKP) side of
the external sense resistor. Kelvin sense connect SRN to the other side of the external sense
resistor with the positive connection to the system (VSYS). For pack-side configurations with lowside sensing, connect SRP to PACK– and SRN to Cell–. See the Simplified Schematic.
No calibration is required. The fuel gauge is pre-calibrated for a standard 10-mΩ, 1% sense
resistor.
6 Specifications
6.1 Absolute Maximum Ratings
Over operating free-air temperature range (unless otherwise noted) (1)
VBAT
VSR
MIN
MAX
UNIT
BAT pin input voltage range
–0.3
6
V
SRP and SRN pins input voltage range
–0.3
VBAT + 0.3
V
2
V
VDD
Differential voltage across SRP and SRN. ABS(SRP – SRN)
VDD pin supply voltage range (LDO output)
–0.3
2
V
VIOD
Open-drain IO pins (SDA, SCL)
–0.3
6
V
VIOPP
Push-pull IO pins (BIN)
–0.3
VDD + 0.3
V
TA
Operating free-air temperature range
–40
85
°C
–65
150
°C
Storage temperature, Tstg
(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.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
4
Electrostatic
discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±1500
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±250
UNIT
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.
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6.3 Recommended Operating Conditions
TA = 30°C and VBAT = 3.6 V (unless otherwise noted)
MIN
CBAT
(1)
CLDO18 (1)
VPU (1)
(1)
NOM
External input capacitor for internal LDO
between BAT and VSS
Nominal capacitor values specified.
Recommend a 5% ceramic X5R-type
External output capacitor for internal LDO capacitor located close to the device.
between VDD and VSS
External pullup voltage for open-drain
pins (SDA, SCL, GPOUT)
MAX
UNIT
0.1
μF
2.2
μF
1.62
3.6
V
Specified by design. Not production tested.
6.4 Thermal Information
bq27220
THERMAL METRIC
(1)
YZF (DSBGA)
UNIT
9 PINS
RθJA
Junction-to-ambient thermal resistance
64.1
°C/W
RθJCtop
Junction-to-case (top) thermal resistance
59.8
°C/W
RθJB
Junction-to-board thermal resistance
52.7
°C/W
ψJT
Junction-to-top characterization parameter
0.3
°C/W
ψJB
Junction-to-board characterization parameter
28.3
°C/W
RθJCbot
Junction-to-case (bottom) thermal resistance
2.4
°C/W
(1)
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953
6.5 Supply Current
TA = 30°C and VBAT = 3.6 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ICC (1)
NORMAL mode current
ILOAD > Sleep Current (2)
50
μA
ISLP (1)
SLEEP mode current
ILOAD < Sleep Current (2)
9
μA
SHUTDOWN mode current
Fuel gauge in host commanded
SHUTDOWN mode.
(LDO regulator output disabled)
0.6
μA
ISD (1)
(1)
(2)
Specified by design. Not production tested.
Wake Comparator Disabled.
6.6 Digital Input and Output DC Characteristics
TA = –40°C to 85°C, typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted)(Force Note1) (1)
PARAMETER
VIH(OD)
TEST CONDITIONS
Input voltage, high (2)
External pullup resistor to VPU
(3)
MIN
TYP
MAX
UNIT
VPU × 0.7
V
VIH(PP)
Input voltage, high
VIL
Input voltage, low (2)
VOL
Output voltage, low (2)
0.6
V
IOH
Output source current, high (2)
0.5
mA
Output sink current, low (2)
IOL(OD)
CIN
Ilkg
(1)
(2)
(3)
(1)
1.4
(3)
V
0.6
V
–3
mA
Input capacitance (2) (3)
5
pF
Input leakage current
(SCL, SDA, BIN, GPOUT)
1
μA
Specified by design. Not production tested.
Open Drain pins: (SCL, SDA, GPOUT)
Push-Pull pin: (BIN)
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6.7 LDO Regulator, Wake-up, and Auto-Shutdown DC Characteristics
TA = –40°C to 85°C, typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted)(Force Note1) (1)
PARAMETER
VBAT
BAT pin regulator input
VDD
Regulator output voltage
UVLOIT+
VBAT undervoltage lock-out
LDO wake-up rising threshold
UVLOIT–
VBAT undervoltage lock-out
LDO auto-shutdown falling threshold
VWU+ (1)
GPOUT (input) LDO Wake-up rising
edge threshold (2)
(1)
(2)
TEST CONDITIONS
MIN
TYP
2.45
LDO Wake-up from SHUTDOWN
mode
MAX
4.5
UNIT
V
1.85
V
2
V
1.95
V
1.2
V
Specified by design. Not production tested.
If the device is commanded to SHUTDOWN via I2C with VBAT > UVLOIT+, a wake-up rising edge trigger is required on GPOUT.
6.8 LDO Regulator, Wake-up, and Auto-shutdown AC Characteristics
TA = –40°C to 85°C, typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted)
PARAMETER
tSHDN
(1)
tSHUP (1)
tVDD
(1)
TEST CONDITIONS
SHUTDOWN entry time
Time delay from SHUTDOWN
command to LDO output disable.
SHUTDOWN GPOUT low time
Minimum low time of GPOUT (input)
in SHUTDOWN before WAKEUP
tWUVDD (1)
Wake-up VDD output delay
tPUCD
Power-up communication delay
Time delay from rising edge of BAT
to the Active state. Includes
firmware initialization time.
TYP
MAX
UNIT
250
ms
μs
10
Initial VDD output delay
Time delay from rising edge of
GPOUT (input) to nominal VDD
output.
(1)
MIN
13
ms
8
ms
250
ms
Specified by design. Not production tested.
6.9 ADC (Temperature and Cell Measurement) Characteristics
TA = –40°C to 85°C; typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted) (Force Note1) (1)
PARAMETER
VIN(BAT)
BAT pin voltage measurement
range
tADC_CONV
Conversion time
TEST CONDITIONS
Voltage divider enabled
MIN
2.45
Effective resolution
(1)
TYP
MAX
4.5
UNIT
V
125
ms
15
bits
Specified by design. Not tested in production.
6.10 Integrating ADC (Coulomb Counter) Characteristics
TA = –40°C to 85°C; typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted)(Force Note1) (1)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VBAT
V
VSRCM
Input voltage range of SRN, SRP
pins
VSRDM
Input differential voltage range of
VSRP–VSRN
tSR_CONV
Conversion time
Single conversion
1
s
Effective Resolution
Single conversion
16
bits
(1)
6
VSS
± 80
mV
Specified by design. Not tested in production.
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6.11 I2C-Compatible Interface Communication Timing Characteristics
TA = –40°C to 85°C; typical values at TA = 30°C and VBAT = 3.6 V (unless otherwise noted) (Force Note1) (1)
MIN
NOM
MAX
UNIT
Standard Mode (100 kHz)
4
μs
4.7
μs
4
μs
4.7
μs
250
ns
td(STA)
Start to first falling edge of SCL
tw(L)
SCL pulse duration (low)
tw(H)
SCL pulse duration (high)
tsu(STA)
Setup for repeated start
tsu(DAT)
Data setup time
Host drives SDA
th(DAT)
Data hold time
Host drives SDA
0
ns
tsu(STOP)
Setup time for stop
4
μs
t(BUF)
Bus free time between stop and
start
66
μs
tf
SCL or SDA fall time (1)
tr
SCL or SDA rise time
fSCL
Clock frequency (2)
Includes Command Waiting Time
300
(1)
ns
300
ns
100
kHz
Fast Mode (400 kHz)
td(STA)
Start to first falling edge of SCL
600
ns
tw(L)
SCL pulse duration (low)
1300
ns
tw(H)
SCL pulse duration (high)
600
ns
tsu(STA)
Setup for repeated start
600
ns
tsu(DAT)
Data setup time
Host drives SDA
100
ns
th(DAT)
Data hold time
Host drives SDA
0
ns
tsu(STOP)
Setup time for stop
600
ns
t(BUF)
Bus free time between stop and
start
66
μs
tf
SCL or SDA fall time (1)
tr
SCL or SDA rise time
fSCL
Clock frequency (2)
(1)
(2)
Includes Command Waiting Time
300
(1)
ns
300
ns
400
kHz
Specified by design. Not production tested.
If the clock frequency (fSCL) is > 100 kHz, use 1-byte write commands for proper operation. All other transactions types are supported at
400 kHz. (See I2C Interface and I2C Command Waiting Time.)
tSU(STA)
tw(H)
tf
tw(L)
tr
t(BUF)
SCL
SDA
td(STA)
tsu(STOP)
tf
tr
th(DAT)
tsu(DAT)
REPEATED
START
STOP
START
Figure 1. I2C-Compatible Interface Timing Diagram
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6.12 SHUTDOWN and WAKE-UP Timing
tPUCD
tSHUP
tVDD
tSHDN
tPUCD
tWUVDD
BAT
VDD
I2C Bus
SHUTDOWN _
ENABLE
SHUTDOWN
GPOUT *
State
Off
WAKE-UP
Active
SHUTDOWN
WAKE-UP
Active
* GPOUT is configured as an input for wake-up signaling.
Figure 2. SHUTDOWN and WAKE-UP Timing Diagram
6.13 Typical Characteristics
0.6%
0.45%
0.4%
Voltage Accuracy Error
Current Accuracy Error
0.5%
0.4%
0.3%
0.2%
0.1%
0
0.35%
0.3%
0.25%
0.2%
0.15%
0.1%
0.05%
-0.1%
-50
0
50
Temperature (qC)
100
0
-60
-40
-20
0
20
40
Temperature (qC)
D001
Figure 3. Current Accuracy Error vs. Temperature
60
80
100
D002
Figure 4. Voltage Accuracy Error vs. Temperature
Internal Temperature Accuracy Error
0
-1%
-2%
-3%
-4%
-5%
-6%
-50
0
50
Temperature (qC)
100
D003
Figure 5. Internal Temperature Accuracy Error vs. Temperature
8
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7 Detailed Description
7.1 Overview
The bq27220 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). The bq27220 monitors charge and discharge activity by sensing the voltage across a
small value resistor (10 mΩ typical) between the SRP and SRN pins and in series with the battery. By integrating
charge passing through the battery, the battery’s SOC is adjusted during battery charge or discharge.
The fuel gauging is derived from the Compensated End of Discharge Voltage (CEDV) method, which uses a
mathematical model to correlate remaining state of charge (RSOC) and voltage near to the end of discharge
state. This requires a full discharge cycle for a single point FCC update. The implementation models cell voltage
(OCV) as a function of battery state of charge (SOC), temperature, and current. The impedance is also a function
of SOC and temperature, all of which can be satisfied by using seven parameters: EMF, C0, R0, T0, R1, TC, C1.
NOTE
The following formatting conventions are used in this document:
Commands: italics with parentheses() and no breaking spaces, for example, Control().
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.
7.2 Functional Block Diagram (System-Side Configuration)
I 2C
Bus
SRN
SCL
Coulomb
Counter
SDA
VSYS
SRP
CPU
Battery Pack
GPOUT
ADC
BAT
PACKP
BIN
T
VDD
1.8 V
LDO
2.2 µF
VSS
1 µF
PACKN
Li-Ion
Cell
Protection
IC
NFET
NFET
7.3 Feature Description
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 within the control and status registers, as well as its data
locations. Commands are sent from the system to the gauge using the I2C serial communications engine, and
can be executed during application development, system manufacture, or end-equipment operation.
The fuel gauge measures the charging and discharging of the battery by monitoring the voltage across a smallvalue sense resistor. When a cell is attached to the fuel gauge, cell impedance is computed based on cell
current, cell open-circuit voltage (OCV), and cell voltage under loading conditions.
The fuel gauge uses an integrated temperature sensor for estimating cell temperature. Alternatively, the host
processor can provide temperature data for the fuel gauge.
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Feature Description (continued)
For more details, see the bq27220 Technical Reference Manual (SLUUBD4).
The external temperature sensing is optimized with the use of a high accuracy negative temperature coefficient
(NTC) thermistor with R25 = 10.0 kΩ ±1%. B25/85 = 3435K ± 1% (such as Semitec NTC 103AT) on the BIN pin.
Alternatively, the bq27220 can also be configured to use its internal temperature sensor or receive temperature
data from the host processor. The bq27220 uses temperature to monitor the battery-pack environment, which is
used for fuel gauging and cell protection functionality.
7.3.1 Communications
7.3.1.1 I2C Interface
The fuel gauge supports the standard I2C read, incremental read, quick read, one-byte write, and incremental
write functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as
1010101. The first 8 bits of the I2C protocol are, therefore, 0xAA or 0xAB for write or read, respectively.
Host generated
S
ADDR[6:0]
0 A
Gauge generated
CMD [7:0]
A
DATA [7:0]
A P
S
ADDR[6:0]
1 A
(a) 1-byte write
S
ADDR[6:0]
0 A
DATA [7:0]
N P
(b) quick read
CMD [7:0]
A Sr
ADDR[6:0]
1 A
DATA [7:0]
N P
(c) 1- byte read
S
ADDR[6:0]
0 A
CMD [7:0]
A Sr
ADDR[6:0]
1 A
DATA [7:0]
A ...
DATA [7:0]
N P
(d) incremental read
S
ADDR[6:0]
0 A
CMD[7:0]
A
DATA [7:0]
A
DATA [7:0]
A
...
A P
(e) incremental write
(S = Start , Sr = Repeated Start , A = Acknowledge , N = No Acknowledge , and P = Stop).
Figure 6. I2C Interface Read and Write Functions
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. “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).
The following command sequences are not supported:
Figure 7. Attempt to Write a Read-Only Address (NACK After Data Sent By Master)
Figure 8. Attempt to Read an Address Above 0x6B (NACK Command)
7.3.1.2 I2C Time Out
The I2C engine releases both SDA and SCL if the I2C bus is held low for 2 seconds. If the fuel gauge is holding
the lines, releasing them frees them for 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.
10
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Feature Description (continued)
7.3.1.3 I2C Command Waiting Time
To ensure proper operation at 400 kHz, a t(BUF) ≥ 66 μs bus-free waiting time must be inserted between all
packets addressed to the fuel gauge. In addition, if the SCL clock frequency (fSCL) is > 100 kHz, use individual 1byte write commands for proper data flow control. Figure 9 shows the standard waiting time required between
issuing the control subcommand the reading the status 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 must not issue any standard command 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]
A P
66ms
S
ADDR [6:0]
0 A
CMD [7:0]
A
DATA [7:0]
A P
66ms
S
ADDR [6:0]
0 A
CMD [7:0]
A Sr
ADDR [6:0]
1 A
DATA [7:0]
A
DATA [7:0]
N P
66ms
N P
66ms
Waiting time inserted between two 1-byte write packets for a subcommand and reading results
(required for 100 kHz < fSCL £ 400 kHz)
S
ADDR [6:0]
0 A
CMD [7:0]
A
S
ADDR [6:0]
0 A
CMD [7:0]
A Sr
DATA [7:0]
ADDR [6:0]
A
1 A
DATA [7:0]
DATA [7:0]
A P
A
66ms
DATA [7:0]
Waiting time inserted between incremental 2-byte write packet for a subcommand and reading results
(acceptable for fSCL £ 100 kHz)
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]
A
DATA [7:0]
A
66ms
Waiting time inserted after incremental read
Figure 9. Standard Waiting Time
7.3.1.4 I2C Clock Stretching
A clock stretch can occur during all modes of fuel gauge operation. In SLEEP mode, a short ≤ 100-µs clock
stretch occurs on all I2C traffic as the device must wake-up to process the packet. In the other modes
(INITIALIZATION, NORMAL), a ≤ 4-ms clock stretching period may occur within packets addressed for the fuel
gauge as the I2C interface performs normal data flow control.
7.4 Device Functional Modes
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL, and
SLEEP. 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. For more details, see the bq27220
Technical Reference Manual (SLUUBD4).
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8 Application and Implementation
NOTE
Information in the following application section is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The bq27220 fuel gauge is a microcontroller peripheral that provides system-side or pack-side fuel gauging for
single-cell Li-Ion batteries. The device requires minimal configuration and uses One-Time Programmable (OTP)
Non-Volatile Memory (NVM). Battery fuel gauging with the fuel gauge requires connections only to PACK+ and
PACK– for a removable battery pack or embedded battery circuit. To allow for optimal performance in the end
application, special considerations must be taken to ensure minimization of measurement error through proper
printed circuit board (PCB) board layout. Such requirements are detailed in Design Requirements.
8.2 Typical Applications
Ext VCC
EXT_VCC
TP4
EXT_VCC
J3
GND
VDD
VDD
J4
R2
1.8 Meg
PGND
EXT_VCC
BIN
JP1
JP2
EXT_VCC
R3
5.1k
J2
J1
SDA
SCL
VSS
R4
10.0k
4
3
2
1
R5
10.0k
GPOUT
GPOUT
SDA
SCL
VDD
U1
PGND
Recommended to be connected
GPOUT
to a GPIO on the host.
BIN
C3
BAT
VDD
B3
A3
A2
SCL
SDA
SRP
SRN
C1
C2
A1
GPOUT
B1
BIN
VSS
B2
TP5
C3
0.47 µF
PGND PGND
Cell+
Cell+
BIN
Cell–
1 TP1
2
3
VDD
C1
2.2 µF
PGND
Load+
TP2
J6
Load-
J7
Pack+
Charger+
BIN
J5
R8
10.0k
C2
1 µF
R1
TP3
0.01
ChargerPack+
PGND
Figure 10. Typical Application for Pack-Side Using Low-Side Sensing
8.2.1 Design Requirements
As shipped from the Texas Instruments factory, many bq27220 parameters in OTP NVM are left in the
unprogrammed state (zero). This partially programmed configuration facilitates customization for each end
application. Upon device reset, the contents of OTP are copied to associated volatile RAM-based data memory
blocks. For proper operation, all parameters in RAM-based data memory require initialization — either by
updating data memory parameters in a lab/evaluation situation or by programming the OTP for customer
production. The bq27220 Technical Reference Manual (SLUUBD4) shows the default value and a typically
expected value appropriate for most of applications.
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Typical Applications (continued)
8.2.2 Detailed Design Procedure
8.2.2.1 BAT Voltage Sense Input
A ceramic capacitor at the input to the BAT pin is used to bypass AC voltage ripple to ground, greatly reducing
its influence on battery voltage measurements. It proves most effective in applications with load profiles that
exhibit high-frequency current pulses (that is, cell phones) but is recommended for use in all applications to
reduce noise on this sensitive high-impedance measurement node.
8.2.2.2 Integrated LDO Capacitor
The fuel gauge has an integrated LDO with an output on the VDD pin of approximately 1.8 V. A capacitor with a
value of at least 2.2 μF should be connected between the VDD pin and VSS. The capacitor must be placed close
to the gauge IC and have short traces to both the VDD pin and VSS. This regulator must not be used to provide
power for other devices in the system.
8.2.2.3 Sense Resistor Selection
Any variation encountered in the resistance present between the SRP and SRN pins of the fuel gauge will affect
the resulting differential voltage, and derived current, that it senses. As such, it is recommended to select a
sense resistor with minimal tolerance and temperature coefficient of resistance (TCR) characteristics. The
standard recommendation based on the best compromise between performance and price is a 1% tolerance, 50ppm drift sense resistor with a 1-W power rating.
8.2.3 External Thermistor Support
The fuel gauge temperature sensing circuitry is designed to work with a negative temperature coefficient-type
(NTC) thermistor with a characteristic 10-kΩ resistance at room temperature (25°C). The default curve-fitting
coefficients configured in the fuel gauge specifically assume a Semitec 103AT type thermistor profile and so that
is the default recommendation for thermistor selection purposes. Moving to a separate thermistor resistance
profile (for example, JT-2 or others) requires an update to the default thermistor coefficients, which can be
modified in RAM to ensure highest accuracy temperature measurement performance.
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Typical Applications (continued)
8.2.4 Application Curves
0.6%
0.45%
0.4%
Voltage Accuracy Error
Current Accuracy Error
0.5%
0.4%
0.3%
0.2%
0.1%
0
-0.1%
-50
0.35%
0.3%
0.25%
0.2%
0.15%
0.1%
0.05%
0
50
Temperature (qC)
100
0
-60
-40
-20
0
20
40
Temperature (qC)
D001
Figure 11. Current Accuracy Error vs. Temperature
60
80
100
D002
Figure 12. Voltage Accuracy Error vs. Temperature
Internal Temperature Accuracy Error
0
-1%
-2%
-3%
-4%
-5%
-6%
-50
0
50
Temperature (qC)
100
D003
Figure 13. Internal Temperature Accuracy Error vs. Temperature
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9 Power Supply Recommendation
9.1 Power Supply Decoupling
The battery connection on the BAT pin is used for two purposes:
• To supply power to the fuel gauge, and
• To provide an input for voltage measurement of the battery.
A capacitor of value of at least 1 µF should be connected between BAT and VSS. The capacitor must be placed
close to the gauge IC and have short traces to both the BAT pin and VSS.
The fuel gauge has an integrated LDO with an output on the VDD pin of approximately 1.8 V. A capacitor of value
of at least 2.2 µF should be connected between the VDD pin and VSS. The capacitor must be placed close to the
gauge IC and have short traces to both the VDD pin and VSS. This regulator must not be used to provide power
for other devices in the system.
10 Layout
10.1 Layout Guidelines
•
•
•
•
A capacitor of value of at least 2.2 µF is connected between the VDD pin and VSS. The capacitor must be
placed close to the gauge IC and have short traces to both the VDD pin and VSS. This regulator must not be
used to provide power for other devices in the system.
It is required to have a capacitor of at least 1.0 µF connect between the BAT pin and VSS if the connection
between the battery pack and the gauge BAT pin has the potential to pick up noise. The capacitor should be
placed close to the gauge IC and have short traces to both the BAT pin and VSS.
If the external pullup resistors on the SCL and SDA lines will be disconnected from the host during low-power
operation, it is recommended to use external 1-MΩ pulldown resistors to VSS to avoid floating inputs to the I2C
engine.
The value of the SCL and SDA pullup resistors should take into consideration the pullup voltage and the bus
capacitance. Some recommended values, assuming a bus capacitance of 10 pF, can be seen in Table 1.
Table 1. Recommended Values for SCL and SDA Pullup Resistors
VPU
RPU
•
•
•
•
•
•
1.8 V
3.3 V
Range
Typical
Range
Typical
400 Ω ≤ RPU ≤ 37.6 kΩ
10 kΩ
900 Ω ≤ RPU ≤ 29.2 kΩ
5.1 kΩ
If the host is not using the GPOUT functionality, then it is recommended that GPOUT be connected to a
GPIO of the host so that in the cases where the device is in SHUTDOWN, toggling GPOUT can wake the
gauge from the SHUTDOWN state.
If the battery pack thermistor is not connected to the BIN pin, the BIN pin should be pulled down to VSS with a
10-kΩ resistor.
The BIN pin should not be shorted directly to VDD or VSS.
The actual device ground is pin B2 (VSS).
The SRP and SRN pins should be Kelvin connected to the RSENSE terminals. SRP to the battery pack side of
RSENSE and SRN to the system side of the RSENSE.
Kelvin connect the BAT pin to the battery PACKP terminal.
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10.2 Layout Example
Kelvin connect SRP
and SRN connections
right at Rsense
terminals
RSENSE
VSYSTEM
If battery pack’s
thermistor will not be
connected to BIN pin, a
10-kΩ pulldown resistor
should be connected to
the BIN pin.
SRP
BAT
SRN
VDD
CBAT
C VDD
VDD
The BIN pin should not be
shorted directly to VDD or
VSS.
Battery Pack
PACK+
Li-Ion
Cell
TS
+
BIN
Vpullup( do not pull to gauge VDD)
VSS
R BIN
RSCL
SCL
GPOUT
R SDA
Place close to
gauge IC. Trace
to pin and VSS
should be short
SDA
R THERM
Protection
IC
PACK-
RGPOUT
NFET
NFET
SCL
Via connects to Power Ground
SDA
GPOUT
Figure 14. EVM Board Layout
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
• bq27220 Technical Reference Manual (SLUUBD4)
• Quickstart Guide for bq27220 (SLUUAP7)
• Single Cell Gas Gauge Circuit Design (SLUA456)
• Key Design Considerations for the bq27500 and bq27501 (SLUA439)
• ESD and RF Mitigation in Handheld Battery Electronics (SLUA460)
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
NanoFree, E2E are trademarks of Texas Instruments.
I2C is a trademark of NXP Semiconductors, N.V.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.5 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.
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PACKAGE OPTION ADDENDUM
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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)
BQ27220YZFR
ACTIVE
DSBGA
YZF
9
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27220
BQ27220YZFT
ACTIVE
DSBGA
YZF
9
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27220
(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
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