UCD90910RGCR

UCD90910 www.ti.com SLVSA81 – JULY 2010 10-Rail Sequencer and System Health Monitor With 10-Fan Control Check for Samples: UCD90910 FEATURES DESCRIPTION • The UCD90910 is a ten-rail I2C / PMBus addressable power-supply sequencer and system-health monitor. The device integrates a 12-bit ADC for monitoring up to 13 power-supply voltage, current, or temperature inputs. • • • • • • • • • Monitor and Sequence Ten Voltage Rails – All Rails Sampled Every 400 ms – 12-Bit ADC With 2.5-V, 0.5% Internal VREF – Sequence Based on Time, Rail and Pin Dependencies – Four Programmable Undervoltage and Overvoltage Thresholds per Monitor Fan Control and Monitoring – Supports Ten Fans With Five User-Defined Speed-vs-Temperature Setpoints – Supports Two-, Three-, and Four-Wire Fans Nonvolatile Error and Peak-Value Logging per Monitor (up to 12 Faults) Closed-Loop Margining for Ten Rails – Margin Output Adjusts Rail Voltage to Match User-Defined Margin Thresholds Programmable Watchdog Timer and System Reset Flexible Digital I/O Configuration Multiphase PWM Clock Generator – Clock Frequencies From 15.259 kHz to 125 MHz – Capability to Configure Independent Clock Outputs for Synchronizing Switch-Mode Power Supplies Internal Temperature Sensor JTAG and I2C™ / SMBus / PMBus Interfaces Full Configuration Update while in Normal Mode Capability Twenty-six GPIO pins can be used for power-supply enables, power-on-reset signals, external interrupts, cascading, or other system functions. Twelve of these pins offer PWM functionality. Using these pins, the UCD90910 offers support for fan control, margining, and general-purpose PWM functions. Fan-control signals can be sent using PMBus commands or generated from one of two built-in fan-control algorithms. PWM outputs combined with temperature and fan-speed measurements provide a complete fan-control solution for up to ten independent fans. The TI Fusion Digital Power™ designer software is provided for device configuration. This PC-based graphical user interface (GUI) offers an intuitive interface for configuring, storing, and monitoring all system operating parameters. 12V 12V OUT 3.3V_UCD I12V TEMP IC 5.1V 12V OUT GPIO VIN MON MON 1.8V OUT MON 0.8V OUT MON I0.8V MON TEMP0.8V MON • • • • Industrial / ATE Telecommunications and Networking Equipment Servers and Storage Systems Any System Requiring Sequencing and Monitoring of Multiple Power Rails 3.3V OUT VOUT /EN GPIO 3.3V OUT DC-DC 1 VFB VIN /EN GPIO VOUT 1.8V OUT LDO1 I12V MON TEMP12V MON TEMP IC VIN UCD90910 APPLICATIONS TEMP12V INA196 V33A V33D 23 V33FB 1 WDI from main processor GPIO WDO GPIO POWER_GOOD GPIO TEMP0.8V 0.8V OUT VOUT /EN GPIO DC-DC 2 VFB INA196 PWM WARN_OC_0.8V_ OR_12V GPIO SYSTEM RESET GPIO OTHER SEQUENCER DONE (CASCADE INPUT) GPIO 2MHz I0.8V Vmarg Closed Loop Margining 4- wire Fan 12 V 12V I2C/ PMBUS JTAG PWM GPIO 25 kHz Fan PWM Fan Tach PWM TACH GND DC Fan 1 2 3 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. Fusion Digital Power is a trademark of Texas Instruments. I2C is a trademark of NXP B.V. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2010, Texas Instruments Incorporated UCD90910 SLVSA81 – JULY 2010 www.ti.com 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. FUNCTIONAL BLOCK DIAGRAM Comparators JTAG Or GPIO I2C/ PMBus Internal Temperature Sensor General Purpose I/O (GPIO) Rail Enables (10 max) 14 Digital Outputs (10 max) 6 Digital Inputs (8 max) Monitor Inputs SEQUENCING ENGINE 13 PWMs Multi-phase PWM (8 max) 12-bit 200ksps, ADC (0.5% Int. Ref) Fan Tach Monitors (10 max) Fan Control (10 max) FLASH Memory User Data, Fault and Peak Logging BOOLEAN Logic Builder 12 Margining Outputs (10 max) GPIO 64-pin QFN ORDERING INFORMATION For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI Web site at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) VALUE UNIT Voltage applied at V33D to DVSS –0.3 to 3.8 V Voltage applied at V33A to AVSS –0.3 to 3.8 V Voltage applied at V33FB to AVSS –0.3 to 5.5 V Voltage applied to any other pin (2) –0.3 to (V33A + 0.3) V –40 to 150 °C Human-body model (HBM) 2.5 kV Charged-device model (CDM) 750 V Storage temperature (Tstg) ESD rating (1) (2) 2 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. All voltages referenced to VSS Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 THERMAL INFORMATION UCD90910 THERMAL METRIC (1) RGC UNITS 64 PINS Junction-to-ambient thermal resistance (2) qJA 26.4 (3) qJCtop Junction-to-case (top) thermal resistance qJB Junction-to-board thermal resistance (4) 1.7 yJT Junction-to-top characterization parameter (5) 0.7 yJB Junction-to-board characterization parameter (6) 8.8 qJCbot Junction-to-case (bottom) thermal resistance (7) 1.7 (1) (2) (3) (4) (5) (6) (7) 21.2 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. The junction-to-ambient thermal resistance under natural convection is obtained in a simulation on a JEDEC-standard, high-K board, as specified in JESD51-7, in an environment described in JESD51-2a. The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific JEDEC-standard test exists, but a close description can be found in the ANSI SEMI standard G30-88. The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB temperature, as described in JESD51-8. The junction-to-top characterization parameter, yJT, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining qJA, using a procedure described in JESD51-2a (sections 6 and 7). The junction-to-board characterization parameter, yJB, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining qJA , using a procedure described in JESD51-2a (sections 6 and 7). The junction-to-case (bottom) thermal resistance is obtained by simulating a cold plate test on the exposed (power) pad. No specific JEDEC standard test exists, but a close description can be found in the ANSI SEMI standard G30-88. RECOMMENDED OPERATING CONDITIONS Supply voltage during operation (V33D, V33DIO, V33A) Operating free-air temperature range, TA MIN NOM MAX 3 3.3 3.6 V 110 °C 125 °C –40 Junction temperature, TJ Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UNIT 3 UCD90910 SLVSA81 – JULY 2010 www.ti.com ELECTRICAL CHARACTERISTICS over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN NOM MAX UNIT SUPPLY CURRENT IV33A VV33A = 3.3 V 8 mA IV33DIO VV33DIO = 3.3 V 2 mA VV33D = 3.3 V 40 mA VV33D = 3.3 V, storing configuration parameters in flash memory 50 mA Supply current (1) IV33D IV33D INTERNAL REGULATOR CONTROLLER INPUTS/OUTPUTS VV33 3.3-V linear regulator VV33FB 3.3-V linear reg feedback IV33FB Series pass base drive Beta Series NPN pass device Emitter of NPN transistor 3.25 VVIN = 12 V 3.3 3.35 4 4.6 10 V V mA 40 EXTERNALLY SUPPLIED 3.3V POWER VV33D, VV33DIO Digital 3.3-V power TA = 25°C 3 3.6 V VV33A Analog 3.3-V power TA = 25°C 3 3.6 V MON1–MON9 0 2.5 V 0.2 2.5 V –2.5 2.5 mV ANALOG INPUTS (MON1–MON13) VMON Input voltage range INL ADC integral nonlinearity Ilkg Input leakage current 3 V applied to pin IOFFSET Input offset current 1-kΩ source impedance RIN Input impedance CIN Input capacitance tCONVERT ADC sample period 14 voltages sampled, 3.89 ms/sample VREF ADC 2.5 V, internal Reference accuracy 0°C to 125°C MON10–MON13 MON1–MON9, ground reference MON10–MON13, ground reference –40°C to 125°C –5 100 nA 5 mA 3 MΩ 10 pF 8 0.5 MΩ 1.5 400 ms –0.5% 0.5% –1% 1% 9 11 ANALOG INPUT (PMBUS_ADDRx, INTERNAL TEMP SENSE) IBIAS Bias current for PMBus addr. pins VADDR_OPEN Voltage – open pin PMBUS_ADDR0, PMBUS_ADDR1 open VADDR_SHORT Voltage – shorted pin PMBUS_ADDR0, PMBUS_ADDR1 short to ground TInternal Internal temperature-sense accuracy Over range from 0°C to 100°C 2.26 –5 mA V 0.124 V 5 °C Dgnd + 0.25 V DIGITAL INPUTS AND OUTPUTS VOL Low-level output voltage IOL = 6 mA (2), V33DIO = 3 V VOH High-level output voltage IOH = –6 mA (3), V33DIO = 3 V VIH High-level input voltage V33DIO = 3 V VIL Low-level input voltage V33DIO = 3.5 V (1) (2) (3) 4 V33DIO – 0.6 2.1 V 3.6 V 1.4 V Typical supply current values are based on device programmed but not configured, and no peripherals connected to any pins. The maximum total current IOLmax, for all outputs combined, should not exceed 12 mA to hold the maximum voltage drop specified. The maximum total current, IOHmax, for all outputs combined, should not exceed 48 mA to hold the maximum voltage drop specified. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 ELECTRICAL CHARACTERISTICS (continued) over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN NOM MAX UNIT FAN CONTROL INPUTS AND OUTPUTS FPWM1-8 TPWM_FREQ FAN-PWM frequency DUTYPWM FAN-PWM duty cycle range 15.260 125000 PWM1 10 PWM2 1 PWM3-4 TachRANGE FAN-TACH range For 1 Tach pulse per revolution. At 2, 3 or 4 pulse/rev, divide by the value TachRES FAN-TACH resolution For 1 Tach pulse per revolution tMIN FAN-TACH minimum pulse width Either positive or negarive polarity kHz 0.001 7800 0 100 % 30 300k RPM 30 RPM 200 µs MARGINING OUTPUTS TPWM_FREQ MARGINING-PWM frequency DUTYPWM FAN-PWM duty cycle range FPWM1-8 PWM3-4 15.260 125000 0.001 7800 0 100 kHz % SYSTEM PERFORMANCE VDDSlew Minimum VDD slew rate VDD slew rate between 2.3 V and 2.9 V VRESET Supply voltage at which device comes out of reset 0.25 V/ms For power-on reset (POR) tRESET Low-pulse duration needed at RESET pin To reset device during normal operation f(PCLK) Internal oscillator frequency TA = 125°C, TA = 25°C 240 tretention Retention of configuration parameters TJ = 25°C 100 Years Write_Cycles Number of nonvolatile erase/write cycles TJ = 25°C 20 K cycles 2.4 2 mS 250 260 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 V MHz 5 UCD90910 SLVSA81 – JULY 2010 www.ti.com I2C / SMBus / PMBus The timing characteristics and timing diagram for the communications interface that supports I2C, SMBus, and PMBus are shown as follows. I2C / SMBus / PMBus TIMING REQUIREMENTS TA = –40°C to 85°C, 3 V < VDD < 3.6 V; typical values at TA = 25°C and VCC = 2.5 V (unless otherwise noted) PARAMETER FSMB TEST CONDITIONS SMBus/PMBus operating frequency 2 FI2C I C operating frequency t(BUF) Bus free time between start and stop t(HD:STA) MIN Slave mode, SMBC 50% duty cycle Slave mode, SCL 50% duty cycle MAX UNIT 10 TYP 400 kHz 10 400 kHz 4.7 ms Hold time after (repeated) start 0.26 ms t(SU:STA) Repeated-start setup time 0.26 ms t(SU:STO) Stop setup time 0.26 ms t(HD:DAT) Data hold time 0 ns t(SU:DAT) Data setup time 50 ns Receive mode t(TIMEOUT) Error signal/detect t(LOW) Clock low period t(HIGH) Clock high period See (1) 35 0.5 See (2) ms ms 0.26 50 ms t(LOW:SEXT) Cumulative clock low slave extend time See (3) 25 ms tf Clock/data fall time See (4) 120 ns tr Clock/data rise time See (5) 120 ns (1) (2) (3) (4) (5) The device times out when any clock low exceeds t(TIMEOUT). t(HIGH), Max, is the minimum bus idle time. SMBC = SMBD = 1 for t > 50 ms causes reset of any transaction that is in progress. This specification is valid when the NC_SMB control bit remains in the default cleared state (CLK[0] = 0). t(LOW:SEXT) is the cumulative time a slave device is allowed to extend the clock cycles in one message from initial start to the stop. Fall time tf = 0.9 VDD to (VILMAX – 0.15) Rise time tr = (VILMAX – 0.15) to (VIHMIN + 0.15) tr t(LOW) tf VIH SMBCLK VIL t(HD:STA) t(HIGH) t(HD:DAT) t(SU:STA) t(SU:STO) t(SU:DAT) VIH SMBDATA VIL t(BUF) P S S P T0406-01 2 Figure 1. I C / SMBus Timing Diagram Start Stop t(LOW:SEXT) t(LOW:MEXT) t(LOW:MEXT) t(LOW:MEXT) PMB_CLK CLKACK CLKACK PMB_DATA T0407-01 Figure 2. Bus Timing in Extended Mode 6 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 DEVICE INFORMATION UCD90910 PIN ASSIGNMENT MON7 62 MON8 63 MON9 UCD90910 GPIO1 11 GPIO2 12 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 AVSS1 40 59 NC1 39 TRST MON10 TMS/GPIO22 MON6 NC2 MON5 6 MON11 5 RGC Package (Top View) NC3 38 MON12 37 TDI/GPIO21 MON13 TDO/GPIO20 MON4 V33FB MON3 4 NC4 3 MON7 36 PMBUS_ADDR0 10 TCK/GPIO19 PMBUS_ADDR1 TRCK MON2 MON8 MON1 2 AVSS3 1 MON9 V33FB BPCAP V33A V33D V33DIO1 V33DIO2 7 44 46 45 58 47 MON1 1 49 48 AVSS2 MON2 2 47 BPCAP 50 MON10 GPIO3 13 MON3 3 46 V33A 52 MON11 GPIO4 14 MON4 4 45 V33D 54 MON12 GPIO13 25 MON5 5 44 V33DIO2 56 MON13 GPIO14 29 MON6 6 43 DVSS3 GPIO15 30 V33DIO1 7 42 PWM3/GPI3 DVSS1 8 41 PWM4/GPI4 RESET 9 40 TRST 15 PMBUS_CLK GPIO16 33 UCD90910 13 36 TCK/GPIO19 GPIO4 14 35 GPIO18 PMBUS_CLK 15 34 GPIO17 GPIO16 60 PMBUS_ADDR1 17 FPWM2/GPIO6 18 FPWM3/GPIO7 19 31 PWM1/GPI1 32 PWM2/GPI2 FPWM5/GPIO9 21 42 PWM3/GPI3 FPWM6/GPIO10 22 41 PWM4/GPI4 NC4 18 19 20 21 22 23 24 25 26 27 28 29 30 31 33 32 FPWM7/GPIO11 23 24 P0056-18 9 DVSS3 57 16 17 20 FPWM8/GPIO12 RESET DVSS2 NC3 AVSS3 NC2 DVSS1 53 55 AVSS2 NC1 AVSS1 51 FPWM4/GPIO8 PMBUS_DATA PWM2/GPI2 GPIO3 FPWM1/GPIO5 GPIO15 PMBUS_ADDR0 PWM1/GPI1 TDO/GPIO20 61 GPIO14 37 PMBUS_CNTRL 12 PMBUS_ALERT GPIO2 DVSS2 PMBUS_CNTRL GPIO13 TDI/GPIO21 28 FPWM8/GPIO12 TMS/GPIO22 38 FPWM7/GPIO11 39 11 FPWM6/GPIO10 10 GPIO1 FPWM5/GPIO9 TRCK 35 FPWM3/GPIO7 34 GPIO18 FPWM4/GPIO8 GPIO17 PMBUS_ALERT FPWM2/GPIO6 PMBUS_DATA FPWM1/GPIO5 16 27 49 48 64 8 26 43 M0178-01 Table 1. PIN FUNCTIONS PIN NAME PIN NO. I/O TYPE DESCRIPTION ANALOG MONITOR INPUTS MON1 1 I Analog input (0 V–2.5 V) MON2 2 I Analog input (0 V–2.5 V) MON3 3 I Analog input (0 V–2.5 V) MON4 4 I Analog input (0 V–2.5 V) MON5 5 I Analog input (0 V–2.5 V) MON6 6 I Analog input (0 V–2.5 V) MON7 59 I Analog input (0 V–2.5 V) Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 7 UCD90910 SLVSA81 – JULY 2010 www.ti.com Table 1. PIN FUNCTIONS (continued) PIN NAME PIN NO. I/O TYPE MON8 62 I DESCRIPTION Analog input (0 V–2.5 V) MON9 63 I Analog input (0 V–2.5 V) MON10 50 I Analog input (0.2 V–2.5 V) MON11 52 I Analog input (0.2 V–2.5 V) MON12 54 I Analog input (0.2 V–2.5 V) MON13 56 I Analog input (0.2 V–2.5 V) GPIO1 11 I/O General-purpose discrete I/O GPIO2 12 I/O General-purpose discrete I/O GPIO3 13 I/O General-purpose discrete I/O GPIO4 14 I/O General-purpose discrete I/O GPIO13 25 I/O General-purpose discrete I/O GPIO14 29 I/O General-purpose discrete I/O GPIO15 30 I/O General-purpose discrete I/O GPIO16 33 I/O General-purpose discrete I/O GPIO17 34 I/O General-purpose discrete I/O GPIO18 35 I/O General-purpose discrete I/O FPWM1/GPIO5 17 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM2/GPIO6 18 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM3/GPIO7 19 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM4/GPIO8 20 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM5/GPIO9 21 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM6/GPIO10 22 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM7/GPIO11 23 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO FPWM8/GPIO12 24 I/O/PWM PWM (15.259 kHz to 125 MHz) or GPIO PWM1/GPI1 31 I/PWM Fixed 10-kHz PWM output or GPI PWM2/GPI2 32 I/PWM Fixed 1-kHz PWM output or GPI PWM3/GPI3 42 I/PWM PWM (0.93 Hz to 7.8125 MHz) or GPI PWM4/GPI4 41 I/PWM PWM (0.93 Hz to 7.8125 MHz) or GPI GPIO PWM OUTPUTS PMBus COMM INTERFACE PMBUS_CLK 15 I/O PMBus clock (must have pullup to 3.3 V) PMBUS_DATA 16 I/O PMBus data (must have pullup to 3.3 V) PMBUS_ALERT 27 O PMBus alert, active-low, open-drain output (must have pullup to 3.3 V) PMBUS_CNTRL 28 I PMBus control PMBUS_ADDR0 61 I PMBus analog address input. Least-significant address bit PMBUS_ADDR1 60 I PMBus analog address input. Most-significant address bit JTAG TRCK 10 O Test return clock TCK/GPIO19 36 I/O Test clock or GPIO TDO/GPIO20 37 I/O Test data out or GPIO TDI/GPIO21 38 I/O Test data in (tie to VDD with 10-kΩ resistor) or GPIO TMS/GPIO22 39 I/O Test mode select (tie to VDD with 10-kΩ resistor) or GPIO TRST 40 I 8 Test reset – tie to ground with 10-kΩ resistor Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Table 1. PIN FUNCTIONS (continued) PIN NAME PIN NO. I/O TYPE DESCRIPTION INPUT POWER AND GROUNDS RESET 9 Active-low device reset input. Hold low for at least 2 ms to reset the device. V33FB 58 3.3-V linear regulator feedback connection V33A 46 Analog 3.3-V supply V33D 45 Digital core 3.3-V supply V33DIO1 7 Digital I/O 3.3-V supply V33DIO2 44 Digital I/O 3.3-V supply BPCAP 47 1.8-V bypass capacitor – tie 0.1-mF capacitor to analog ground. AVSS1 49 Analog ground AVSS2 48 Analog ground AVSS3 64 Analog ground DVSS1 8 Digital ground DVSS2 26 Digital ground DVSS3 43 Digital ground QFP ground pad NA Thermal pad – tie to ground plane. FUNCTIONAL DESCRIPTION TI FUSION GUI The Texas Instruments Fusion Digital Power Designer is provided for device configuration. This PC-based graphical user interface (GUI) offers an intuitive I2C/PMBus interface to the device. It allows the design engineer to configure the system operating parameters for the application without directly using PMBus commands, store the configuration to on-chip nonvolatile memory, and observe system status (voltage, temperature, etc). Fusion Digital Power Designer is referenced throughout the data sheet as Fusion GUI and many sections include screenshots. The Fusion GUI can be downloaded from www.ti.com. PMBUS INTERFACE The PMBus is a serial interface specifically designed to support power management. It is based on the SMBus specification that is built on the I2C physical interface. The UCD90910 supports revision 1.1 of the PMBus standard. Wherever possible, standard PMBus commands are used to support the function of the device. For unique features of the UCD90910, MFR_SPECIFIC commands are defined to configure or activate those features. These commands are defined in the UCD90xxx Sequencer and System Health Controller PMBUS Command Reference (SLVU352). This document makes frequent mention of the PMBus specification. Specifically, this document is PMBus Power System Management Protocol Specification Part II – Command Language, Revision 1.1, dated 5 February 2007. The specification is published by the Power Management Bus Implementers Forum and is available from www.pmbus.org. The UCD90910 is PMBus compliant, in accordance with the Compliance section of the PMBus specification. The firmware is also compliant with the SMBus 1.1 specification, including support for the SMBus ALERT function. The hardware can support either 100-kHz or 400-kHz PMBus operation. THEORY OF OPERATION Modern electronic systems often use numerous microcontrollers, DSPs, FPGAs, and ASICs. Each device can have multiple supply voltages to power the core processor, analog-to-digital converter, or I/O. These devices are typically sensitive to the order and timing of how the voltages are sequenced on and off. The UCD90910 can sequence supply voltages to prevent malfunctions, intermittent operation, or device damage caused by improper power up or power down. Appropriate handling of under- and overvoltage faults, overcurrent faults and overtemperature faults can extend system life and improve long-term reliability. The UCD90910 stores power supply faults to on-chip nonvolatile flash memory for aid in system failure analysis. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 9 UCD90910 SLVSA81 – JULY 2010 www.ti.com Tach monitor inputs, PWM outputs, and temperature measurements can be combined, with a choice between two built-in fan-control algorithms to provide a stand-alone fan controller for independent operation of up to ten fans. System reliability can be improved through four-corner testing during system verification. During four-corner testing, the system is operated at the minimum and maximum expected ambient temperature and with each power supply set to the minimum and maximum output voltage, commonly referred to as margining. The UCD90910 can be used to implement accurate closed-loop margining of up to 10 power supplies. The UCD90910 ten-rail sequencer can be used in a PMBus- or pin-based control environment. The Fusion GUI provides a powerful but simple interface for configuring sequencing solutions for systems with between one and ten power supplies using 13 analog voltage-monitor inputs, four GPIs and 22 highly configurable GPIOs. A rail can include voltage, temperature, current, a power-supply enable and a margining output. At least one must be included in a rail definition. Once the user has defined how the power-supply rails should operate in a particular system, analog input pins and GPIOs can be selected to monitor and enable each supply (Figure 3). Figure 3. Fusion GUI Pin-Assignment Tab After the pins have been configured, other key monitoring and sequencing criteria are selected for each rail from the Vout Config tab (Figure 4): • Nominal operating voltage (Vout) • Undervoltage (UV) and overvoltage (OV) warning and fault limits • Margin-low and margin-high values • Power-good on and power-good off limits • PMBus or pin-based sequencing control (On/Off Config) • Rails and GPIs for Sequence On dependencies 10 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com • • • • SLVSA81 – JULY 2010 Rails and GPIs for Sequence Off dependencies Turn-on and turn-off delay timing Maximum time allowed for a rail to reach POWER_GOOD_ON or POWER_GOOD_OFF after being enabled or disabled Other rails to turn off in case of a fault on a rail (fault-shutdown slaves) Figure 4. Fusion GUI Vout-Config Tab The Synchronize margins/limits/PG to Vout checkbox is an easy way to change the nominal operating voltage of a rail and also update all of the other limits associated with that rail according to the percentages shown to the right of each entry. The plot in the upper left section of Figure 4 shows a simulation of the overall sequence-on and sequence-off configuration, including the nominal voltage, the turn-on and turn-off delay times, the power-good on and power-good off voltages and any timing dependencies between the rails. After a rail voltage has reached its POWER_GOOD_ON voltage and is considered to be in regulation, it is compared against two UV and two OV thresholds in order to determine if a warning or fault limit has been exceeded. If a fault is detected, the UCD90910 responds based on a variety of flexible, user-configured options. Faults can cause rails to restart, shut down immediately, sequence off using turn-off delay times, or shut down a group of rails and sequence them back on. Different types of faults can result in different responses. Fault responses, along with a number of other parameters including user-specific manufacturing information and external scaling and offset values, are selected in the different tabs within the Configure funciton of the Fusion GUI. Once the configuration satisfies the user requirements, it can be written to device SRAM if Fusion GUI is connected to a UCD90910 using an I2C/PMBus. SRAM contents can then be stored to data flash memory so that the configuration remains in the device after a reset or power cycle. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 11 UCD90910 SLVSA81 – JULY 2010 www.ti.com The Fusion GUI Monitor page has a number of options, including a device dashboard and a system dashboard, for viewing and controlling device and system status. Figure 5. Fusion GUI Monitor Page With System Dashboard The UCD90910 also has status registers for each rail and the capability to log faults to flash memory for use in system troubleshooting. This is helpful in the event of a power-supply or system failure. The status registers (Figure 6) and the fault log (Figure 7) are available in the Fusion GUI. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference (SLVU352) and the PMBus specification for detailed descriptions of each status register and supported PMBus commands. 12 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Figure 6. Fusion GUI Rail-Status Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 13 UCD90910 SLVSA81 – JULY 2010 www.ti.com Figure 7. Fusion GUI Flash-Error Log (Logged Faults) POWER-SUPPLY SEQUENCING The UCD90910 can control the turn-on and turn-off sequencing of up to ten voltage rails by using a GPIO to set a power-supply enable pin high or low. In PMBus-based designs, the system PMBus master can initiate a sequence-on event by asserting the PMBUS_CNTRL pin or by sending the OPERATION command over the I2C serial bus. In pin-based designs, the PMBUS_CNTRL pin can also be used to sequence-on and sequence-off. The auto-enable setting ignores the OPERATION command and the PMBUS_CNTRL pin. Sequence-on is started at power up after any dependencies and time delays are met for each rail. A rail is considered to be on or within regulation when the measured voltage for that rail crosses the power-good on (POWER_GOOD_ON (1)) limit. The rail is still in regulation until the voltage drops below power-good off (POWER_GOOD_OFF). In the case that there isn't voltage monitoring set for a given rail, that rail is considered ON if it is commanded on (either by OPERATION command, PMBUS CNTRL pin, or auto-enable) and (TON_DELAY + TON_MAX_FAULT_LIMIT) time passes. Also, a rail is considered OFF if that rail is commanded OFF and (TOFF_DELAY + TOFF_MAX_WARN_LIMIT) time passes (1) 14 In this document, configuration parameters such as Power Good On are referred to using Fusion GUI names. The UCD90xxx Sequencer and System Health Controller PMBus Command Reference name is shown in parentheses (POWER_GOOD_ON) the first time the parameter appears. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Turn-on Sequencing The following sequence-on options are supported for each rail: • Monitor only – do not sequence-on • Fixed delay time after an OPERATION command to turn on • Fixed delay time after assertion of the PMBUS_CNTRL pin • Fixed time after one or a group of parent rails achieves regulation (POWER_GOOD_ON) • Fixed time after a designated GPI has reached a user-specified state • Any combination of the previous options The maximum TON_DELAY time is 3276 ms. Turn-off Sequencing The following sequence-off options are supported for each rail: • Monitor only – do not sequence-off • Fixed delay time after an OPERATION command to turn off • Fixed delay time after deassertion of the PMBUS_CNTRL pin • Fixed time after one or a group of parent rails drop below regulation (POWER_GOOD_OFF) • Fixed delay time in response to an undervoltage, overvoltage, undercurrent, overcurrent, undertemperature, overtemperature, or max turn-on fault on the rail • Fixed delay time in response to a fault on a different rail when set as a fault shutdown slave to the faulted rail • Fixed delay time in response to a GPI reaching a user-specified state • Any combination of the previous options The maximum TOFF_DELAY time is 3276 ms. PMBUS_CNTRL PIN TON_DELAY[1] RAIL 1 EN POWER_GOOD_ON[1] RAIL 1 VOLTAGE TOFF_DELAY[1] POWER_GOOD_OFF[1] TON_DELAY[2] RAIL 2 EN TOFF_DELAY[2] RAIL 2 VOLTAGE TON_MAX_FAULT _LIMIT[2] Rail 1 and Rail 2 are both sequenced “ON” and “OFF” by the PMBUS_CNTRL pin only Rail 2 has Rail 1 as an “ON” dependency TOFF_MAX_WARN_LIMIT[2] Figure 8. Sequence-on and Sequence-off Timing Sequencing Configuration Options In addition to the turn-on and turn-off sequencing options, the time between when a rail is enabled and when the monitored rail voltage must reach its power-good-on setting can be configured using max turn-on (TON_MAX_FAULT_LIMIT). Max turn-on can be set in 1-ms increments. A value of 0 ms means that there is no limit and the device can try to turn on the output voltage indefinitely. Rails can be configured to turn off immediately or to sequence-off according to user-defined delay times. A sequenced shutdown is configured by selecting the appropriate turn-off delay (TOFF_DELAY) times for each rail. The turn-off delay times begin when the PMBUS_CNTRL pin is deasserted, when the PMBus OPERATION command is used to give a soft-stop command, or when a fault occurs on a rail that has other rails set as fault-shutdown slaves. Shutdowns on one rail can initiate shutdowns of other rails or controllers. In systems with multiple UCD90910s, it is possible for each controller to be both a master and a slave to another controller. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 15 UCD90910 SLVSA81 – JULY 2010 www.ti.com MONITORING The UCD90910 has 13 monitor input pins (MONx) that are multiplexed into a 2.5V referenced 12-bit ADC. The monitor pins can be configured so that they can measure voltage signals to report voltage, current and temperature type measurements. A single rail can include all three measurement types, each monitored on separate MON pins. If a rail has both voltage and current assigned to it, then the user can calculate power for the rail. Digital filtering applied to each MON input depends on the type of signal. Voltage inputs have no filtering. Current and temperature inputs have a low-pass filter. Although the monitor results can be reported with a resolution of about 15 mV, the real conversion resolution of 610 mV is fixed by the 2.5-V reference and the 12-bit ADC. Table 2. Voltage Range and Resolution VOLTAGE RANGE (Volts) RESOLUTION (millivolts) 0 to 127.99609 3.90625 0 to 63.99805 1.956313 0 to 31.99902 0.97656 0 to 15.99951 0.48824 0 to 7.99976 0.24414 0 to 3.99988 0.12207 0 to 1.99994 0.06104 0 to 0.99997 0.03052 VOLTAGE MONITORING Up to 10 rail voltages can be monitored using the analog input pins. The input voltage range is 0 V–2.5 V for MON pins 1–6, 59, 62 and 63. Pins 50, 52, 54, and 56 can measure down to 0.2 V. Any voltage between 0 V and 0.2 V on these pins is read as 0.2 V. External resistors can be used to attenuate voltages higher than 2.5 V. The ADC operates continuously, requiring 3.89 ms to convert a single analog input and 54.5 ms to convert all 14 of the analog inputs, including the onboard temperature sensor. Each rail is sampled by the sequencing and monitoring algorithm every 400 ms. The maximum source impedance of any sampled voltage should be less than 4 kΩ. The source impedance limit is particularly important when a resistor-divider network is used to lower the voltage applied to the analog input pins. MON1 - MON6 can be configured using digital hardware comparators, which can be used to achieve faster fault responses. Each hardware comparator has four thresholds (two UV (Fault and Warning) and two OV (Fault and Warning)). The hardware comparators respond to UV or OV conditions in about 80 ms (faster than 400 µs for the ADC inputs) and can be used to disable rails or assert GPOs. The only fault response available for the hardware comparators is to shut down immediately. An internal 2.5-V reference is used by the ADC. The ADC reference has a tolerance of ±0.5% between 0°C and 125°C and a tolerance of ±1% between –40°C and 125°C. An external voltage divider is required for monitoring voltages higher than 2.5 V. The nominal rail voltage and the external scale factor can be entered into the Fusion GUI and are used to report the actual voltage being monitored instead of the ADC input voltage. The nominal voltage is used to set the range and precision of the reported voltage according to Table 2. 16 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 MON1 – MON6 MON1 MON2 . . . . MON13 Analog Inputs (13) M U X 12-bit SAR ADC 200ksps MON1 – MON13 Internal Temp Sense Fast Digital Comparators Glitch Filter Internal 2.5Vref 0.5% Figure 9. Monitoring Block Diagram CURRENT MONITORING Current can be monitored using the analog inputs. External circuitry, see Figure 10, must be used in order to convert the current to a voltage within the range of the UCD90910 MONx input being used. If a monitor input is configured as a current, the measurements are smoothed by a sliding-average digital filter. The current for 1 rail is measured every 200µs. If the device is programmed to support 10 rails (independent of current not being monitored at all rails), then each rail's current will get measured every 2ms. The current calculation is done with a sliding average using the last 4 measurements. The filter reduces the probability of false fault detections, and introduces a small delay to the current reading. If a rail is defined with a voltage monitor and a current monitor, then monitoring for undercurrent warnings begins once the rail voltage reaches POWER_GOOD_ON. If the rail does not have a voltage monitor, then current monitoring begins after TON_DELAY. The device supports multiple PMBus commands related to current, including READ_IOUT, which reads external currents from the MON pins; IOUT_OC_FAULT_LIMIT, which sets the overcurrent fault limit; IOUT_OC_WARN_LIMIT, which sets the overcurrent warning limit; and IOUT_UC_FAULT_LIMIT, which sets the undercurrent fault limit. The UCD90xxx Sequencer and System Health Controller PMBus Command Reference contains a detailed description of how current fault responses are implemented using PMBus commands. IOUT_CAL_GAIN is a PMBus command that allows the scale factor of an external current sensor and any amplifiers or attenuators between the current sensor and the MON pin to be entered by the user in milliohms. IOUT_CAL_OFFSET is the current that results in 0 V at the MON pin. The combination of these PMBus commands allows current to be reported in amperes. The example below using the INA196 would require programming IOUT_CAL_GAIN to Rsense(mΩ)×20. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 17 UCD90910 SLVSA81 – JULY 2010 www.ti.com MONx VOUT Vin+ AVSS1 Rsense GND Vin3.3V Current Path INA196 UCD90910 V+ Gain = 20V/V Figure 10. Current Monitoring Circuit Example Using the INA196 REMOTE TEMPERATURE MONITORING AND INTERNAL TEMPERATURE SENSOR The UCD90910 has support for internal and remote temperature sensing. The internal temperature sensor requires no calibration and can report the device temperature via the PMBus interface. The remote temperature sensor can report the remote temperature by using a configurable gain and offset for the type of sensor that is used in the application such as a linear temperature sensor (LTS) connected to the analog inputs. External circuitry must be used in order to convert the temperature to a voltage within the range of the UCD90910 MONx input being used. If an input is configured as a temperature, the measurements are smoothed by a sliding average digital filter. The temperature for 1 rail is measured every 100ms. If the device is programmed to support 10 rails (independent of temperature not being monitored at all rails), then each rail's temperature will get measured every 1s. The temperature calculation is done with a sliding average using the last 16 measurements. The filter reduces the probability of false fault detections, and introduces a small delay to the temperature reading. The internal device temperature is measured using a silicon diode sensor with an accuracy of ±5°C and is also monitored using the ADC. Temperature monitoring begins immediately after reset and initialization. The device supports multiple PMBus commands related to temperature, including READ_TEMPERATURE_1, which reads the internal temperature; READ_TEMPERATURE_2, which reads external temperatures; and OT_FAULT_LIMIT and OT_WARN_LIMIT, which set the overtemperature fault and warning limit. The UCD90xxx Sequencer and System Health Controller PMBus Command Reference contains a detailed description of how temperature-fault responses are implemented using PMBus commands. TEMPERATURE_CAL_GAIN is a PMBus command that allows the scale factor of an external temperature sensor and any amplifiers or attenuators between the temperature sensor and the MON pin to be entered by the user in °C/V. TEMPERATURE_CAL_OFFSET is the temperature that results in 0 V at the MON pin. The combination of these PMBus commands allows temperature to be reported in degrees Celsius. 18 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 UCD90910 TMP20 MONx VOUT AVSS1 GND 3.3V V+ Vout = -11.67mV/°C x T + 1.8583 at -40°C < T < 85°C Figure 11. Remote Temperature Monitoring Circuit Example Using the TMP20 TEMPERATURE BY HOST INPUT If the host system has the option of not using the temperature-sensing capability of the UCD90910, it can still provide the desired temperature to the UCD90910 through PMBus. The host may have temperature measurements available through I2C or SPI interfaced temperature sensors. The UCD90910 would use the temperature given by the host in place of an external temperature measurement for a given rail. The temperature provided by the host would still be used for detecting overtemperature warnings or faults, logging peak temperatures, input to Boolean logic-builder functions, and feedback for the fan-control algorithms. To write a temperature associated with a rail, the PMBus command used is the READ_TEMPERATURE_2 command. If the host writes that command, the value written will be used as the temperature until another value is written. This is true whether a monitor pin was assigned to the temperature or not. When there is a monitor pin associated with the temperature, once READ_TEMPERATURE_2 is written, the monitor pin is not used again until the part is reset. When there is not a monitor pin associated with the temperature, the internal temperature sensor is used for the temperature until the READ_TEMPERATURE_2 command is written. UCD90910 Fan Control REMOTE TEMP SENSOR Faults and Warnings I2C I2C or SPI HOST READ_TEMPERATURE_2 Logged Peak Temperatures Boolean Logic Figure 12. Temperature Provided by Host FAULT RESPONSES AND ALERT PROCESSING Device monitors that the rail stays within a window of normal operation. There are two programmable warning levels (under and over) and two programmable fault levels (under and over). When any monitored voltage, current, or temperature goes outside of the warning or fault window, the PMBALERT# pin is asserted immediately, and the appropriate bits are set in the PMBus status registers (see Figure 6). Detailed descriptions of the status registers are provided in the UCD90xxx Sequencer and System Health Controller PMBus Command Reference and the PMBus Specification. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 19 UCD90910 SLVSA81 – JULY 2010 www.ti.com A programmable glitch filter can be enabled or disabled for each MON input. A glitch filter for an input defined as a voltage can be set between 0 and 102 ms with 400-ms resolution. A glitch filter for an input defined as a current or temperature can be between 0 and 25.5 seconds with 100-ms resolution. The longer time constants are due to the fixed low-pass digital filters associated with current and temperature inputs. Fault-response decisions are based on results from the 12-bit ADC. The device cycles through the ADC results and compares them against the programmed limits. The time to respond to an individual event is determined by when the event occurs within the ADC conversion cycle and the selected fault response. PMBUS_CNTRL PIN RAIL 1 EN TON_DELAY[1] TOFF_DELAY[1] TIME BETWEEN RESTARTS TIME BETWEEN RESTARTS MAX_GLITCH_TIME + TOFF_DELAY[1] MAX_GLITCH_TIME + TOFF_DELAY[1] TIME BETWEEN RESTARTS VOUT_OV_FAULT _LIMIT VOUT_UV_FAULT _LIMIT RAIL 1 VOLTAGE POWER_GOOD_ON[1] MAX_GLITCH_TIME TON_DELAY[2] RAIL 2 EN TOFF_DELAY[1] MAX_GLITCH_TIME MAX_GLITCH_TIME TOFF_DELAY[2] RAIL 2 VOLTAGE Rail 1 and Rail 2 are both sequenced “ON” and “OFF” by the PMBUS_CNTRL pin only Rail 2 has Rail 1 as an “ON” dependency Rail 1 has Rail 2 as a Fault Shutdown Slave Rail 1 is set to use the glitch filter for UV or OV events Rail 1 is set to RESTART 3 times after a UV or OV event Rail 1 is set to shutdown with delay for a OV event Figure 13. Sequencing and Fault-Response Timing PMBUS_CNTRL PIN TON_DELAY[1] RAIL 1 EN Rail 1 and Rail 2 are both sequenced “ON” and “OFF” by the PMBUS_CNTRL pin only Time Between Restarts Rail 2 has Rail 1 as an “ON” dependency Rail 1 is set to shutdown immediately and RESTART 1 time in case of a Time On Max fault POWER_GOOD_ON[1] POWER_GOOD_ON[1] RAIL 1 VOLTAGE TON_MAX_FAULT_LIMIT[1] TON_DELAY[2] TON_MAX_FAULT_LIMIT[1] RAIL 2 EN RAIL 2 VOLTAGE Figure 14. Maximum Turn-on Fault The configurable fault limits are: TON_MAX_FAULT – Flagged if a rail that is enabled does not reach the POWER_GOOD_ON limit within the configured time VOUT_UV_WARN – Flagged if a voltage rail drops below the specified UV warning limit after reaching the POWER_GOOD_ON setting VOUT_UV_FAULT – Flagged if a rail drops below the specified UV fault limit after reaching the POWER_GOOD_ON setting VOUT_OV_WARN – Flagged if a rail exceeds the specified OV warning limit at any time during startup or operation VOUT_OV_FAULT – Flagged if a rail exceeds the specified OV fault limit at any time during startup or operation 20 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 MAX_TOFF_WARN – Flagged if a rail that is commanded to shut down does not reach 12.5% of the nominal rail voltage within the configured time Faults are more serious than warnings. The PMBALERT# pin is always asserted immediately if a warning or fault occurs. If a warning occurs, the following takes place: Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 21 UCD90910 SLVSA81 – JULY 2010 www.ti.com Warning Actions — Immediately assert the PMBALERT# pin — Status bit is flagged — Assert a GPIO pin (optional) — Warnings are not logged to flash A number of fault response options can be chosen from: Fault Responses — Continue Without Interruption: Flag the fault and take no action — Shut Down Immediately: Shut down the faulted rail immediately and restart according to the rail configuration — Shut Down using TOFF_DELAY: If a fault occurs on a rail, exhaust whatever retries are configured. If the rail does not come back, schedule the shutdown of this rail and all fault-shutdown slaves. All selected rails, including the faulty rail, are sequenced off according to their T_OFF_DELAY times. If Do Not Restart is selected, then sequence off all selected rails when the fault is detected. Restart — Do Not Restart: Do not attempt to restart a faulted rail after it has been shut down. — Restart Up To N Times: Attempt to restart a faulted rail up to 14 times after it has been shut down. The time between restarts is measured between when the rail enable pin is deasserted (after any glitch filtering and turn-off delay times, if configured to observe them) and then reasserted. It can be set between 0 and 1275 ms in 5-ms increments. — Restart Continuously: Same as Restart Up To N Times except that the device continues to restart until the fault goes away, it is commanded off by the specified combination of PMBus OPERATION command and PMBUS_CNTRL pin status, the device is reset, or power is removed from the device. — Shut Down Rails and Sequence On (Re-sequence): Shut down selected rails immediately or after continue-operation time is reached and then sequence-on those rails using turn-on delay times SHUT DOWN ALL RAILS AND SEQUENCE ON (RESEQUENCE) In response to a fault, or a RESEQUENCE command, the UCD90910 can be configured to turn off a set of rails and then sequence them back on. To sequence all rails in the system, then all rails must be selected as fault-shutdown slaves of the faulted rail. The rails designated as fault-shutdown slaves will do soft shutdowns regardless of whether the faulted rail is set to stop immediately or stop with delay. Shut-down-all-rails and sequence-on are not performed until retries are exhausted for a given fault. While waiting for the rails to turn off, an error is reported if any of the rails reaches its TOFF_MAX_WARN_LIMIT. There is a configurable option to continue with the resequencing operation if this occurs. After the faulted rail and fault-shutdown slaves sequence-off, the UCD90910 waits for a programmable delay time between 0 and 1275 ms in increments of 5 ms and then sequences-on the faulted rail and fault-shutdown slaves according to the start-up sequence configuration. This is repeated until the faulted rail and fault-shutdown slaves successfully achieve regulation or for a user-selected 1, 2, 3, or 4 times. If the resequence operation is successful, the resequence counter is reset if all of the rails that were resequenced maintain normal operation for one second. If the rails are resequenced the maximum number times and they fail to reach normal operation, a device reset is required to reset the resequence counter. Once shut-down-all-rails and sequence-on begin, any faults on the fault-shutdown slave rails are ignored. If there are two or more simultaneous faults with different fault-shutdown slaves, the more conservative action is taken. For example, if a set of rails is already on its second resequence and the device is configured to resequence three times, and another set of rails enters the resequence state, that second set of rails is only resequenced once. Another example – if one set of rails is waiting for all of its rails to shut down so that it can resequence, and another set of rails enters the resequence state, the device now waits for all rails from both sets to shut down before resequencing. 22 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 GPIOs The UCD90910 has 22 GPIO pins that can function as either inputs or outputs. Each GPIO has configurable output mode options including open-drain or push-pull outputs that can be actively driven to 3.3 V or ground. There are an additional four pins that can be used as either inputs or PWM outputs but not as GPOs. Table 3 lists possible uses for the GPIO pins and the maximum number of each type for each use. GPIO pins can be dependents in sequencing and alarm processing. They can also be used for system-level functions such as external interrupts, power-goods, resets, or for the cascading of multiple devices. GPOs can be sequenced up or down by configuring a rail without a MON pin but with a GPIO set as an enable. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 23 UCD90910 SLVSA81 – JULY 2010 www.ti.com Table 3. GPIO Pin Configuration Options PIN NAME PIN RAIL EN (10 MAX) GPI (8 MAX) GPO (10 MAX) FAN TACH (10 MAX) FAN PWM (10 MAX) PWM OUT (12 MAX) MARGIN PWM (10 MAX) FPWM1/GPIO5 17 X X X X X X X FPWM2/GPIO6 18 X X X X X X X FPWM3/GPIO7 19 X X X X X X X FPWM4/GPIO8 20 X X X X X X X FPWM5/GPIO9 21 X X X X X X X FPWM6/GPIO10 22 X X X X X X X FPWM7/GPIO11 23 X X X X X X X FPWM8/GPIO12 24 X X X X X X X FANTAC1/GPI1/PWM1 31 X X X FANTAC2/GPI2/PWM2 32 X X X FANTAC3/GPI3/PWM3 42 X X X X X FANTAC4/GPI4/PWM4 41 X X X X X GPIO1 11 X X X X GPIO2 12 X X X X GPIO3 13 X X X X GPIO4 14 X X X X GPIO13 25 X X X X GPIO14 29 X X X X GPIO15 30 X X X X GPIO16 33 X X X X GPIO17 34 X X X X GPIO18 35 X X X X TCK/GPIO19 36 X X X X TDO/GPIO20 37 X X X X TDI/GPIO21 38 X X X X TMS/GPIO22 39 X X X X GPO Control The GPIOs when configured as outputs can be controlled by PMBus commands or through logic defined in internal Boolean function blocks. Controlling GPOs by PMBus commands (GPIO_SELECT and GPIO_CONFIG) can be used to have control over LEDs, enable switches, etc. with the use of an I2C interface. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference for details on controlling a GPO using PMBus commands. GPO Dependencies GPIOs can be configured as outputs that are based on Boolean combinations of up to four ANDs all ORed together (Figure 15). Inputs to the logic blocks can include GPIs and rail-status flags. One rail status type is selectable as an input for each AND gate in a Boolean block. For a selected rail status, the status flags of all active rails can be included as inputs to the AND gate. _LATCH rail-status types stay asserted until cleared by a MFR PMBus command or by a specially configured GPI pin. The different rail-status types are shown in Table 4. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference for complete definitions of rail-status types. 24 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 GPI_INVERSE(0) GPI_POLARITY(0) GPI_ENABLE(0) 1 _GPI(0) GPI(0) _GPI(1:7) Sub block repeated for each of GPI(1:7) _STATUS(9) _STATUS(0:8) There is one STATUS_TYPE_SELECT for each of the four AND gates in a boolean block STATUS_TYPE_SELECT STATUS(0) _GPI(1:7) GPO_INVERSE(x) _STATUS(0:8) Status Type 1 STATUS(1) GPOx _GPI(1:7) _STATUS(0:8) Status Type 33 Sub block repeated for each of STATUS(0:8) STATUS_INVERSE(9) _GPI(1:7) _STATUS(0:8) STATUS_ENABLE(9) STATUS(9) 1 Figure 15. Boolean Logic Combinations Figure 16. Fusion GUI Boolean Logic Builder Table 4. Rail-Status Types for Boolean Logic Rail-Status Types POWER_GOOD IOUT_UC_FAULT TON_MAX_FAULT_LATCH MARGIN_EN TEMP_OT_FAULT TOFF_MAX_WARN_LATCH Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 25 UCD90910 SLVSA81 – JULY 2010 www.ti.com Table 4. Rail-Status Types for Boolean Logic (continued) Rail-Status Types MRG_LOW_nHIGH TEMP_OT_WARN IOUT_OC_FAULT_LATCH VOUT_OV_FAULT SEQ_ON_TIMEOUT IOUT_OC_WARN_LATCH VOUT_OV_WARN SEQ_OFF_TIMEOUT IOUT_UC_FAULT_LATCH VOUT_UV_WARN FAN_FAULT TEMP_OT_FAULT_LATCH VOUT_UV_FAULT SYSTEM_WATCHDOG_TIMEOUT TEMP_OT_WARN_LATCH TON_MAX_FAULT VOUT_OV_FAULT_LATCH SEQ_ON_TIMEOUT_LATCH TOFF_MAX_WARN VOUT_OV_WARN_LATCH SEQ_OFF_TIMEOUT_LATCH IOUT_OC_FAULT VOUT_UV_WARN_LATCH FAN_FAULT_LATCH IOUT_OC_WARN VOUT_UV_FAULT_LATCH SYSTEM_WATCHDOG_TIMEOUT_LATCH GPI Special Functions Figure 17 lists and describes five special input functions for which GPIs can be used. There can be no more than one pin assigned to each of these functions. Figure 17. GPI Configuration – Special Input Functions Power-Supply Enables Each GPIO can be configured as a rail-enable pin with either active-low or active-high polarity. Output mode options include open-drain or push-pull outputs that can be actively driven to 3.3 V or ground. During reset, the GPIO pins are high-impedance except for FPWM/GPIO pins 17–24, which are driven low. External pulldown or pullup resistors can be tied to the enable pins to hold the power supplies off during reset. The UCD90910 can support a maximum of 10 enable pins. NOTE GPIO pins that have FPWM capability (pins 17-24) should only be used as power-supply enable signals if the signal is active high. 26 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Cascading Multiple Devices A GPIO pin can be used to coordinate multiple controllers by using it as a power good-output from one device and connecting it to the PMBUS_CNTRL input pin of another. This imposes a master/slave relationship among multiple devices. During startup, the slave controllers initiate their start sequences after the master has completed its start sequence and all rails have reached regulation voltages. During shutdown, as soon as the master starts to sequence-off, it sends the shut-down signal to its slaves. A shutdown on one or more of the master rails can initiate shutdowns of the slave devices. The master shutdowns can be initiated intentionally or by a fault condition. This method works to coordinate multiple controllers, but it does not enforce interdependency between rails within a single controller. The PMBus specification implies that the power-good signal is active when ALL the rails in a controller are regulating at their programmed voltage. The UCD90910 allows GPIOs to be configured to respond to a desired subset of power-good signals. PWM Outputs FPWM1-8 Pins 17–24 can be configured as fast pulse-width modulators (FPWMs). The frequency range is 15.260 kHz to 125 MHz. FPWMs can be configured as closed-loop margining outputs, fan controllers or general-purpose PWMs. Any FPWM pin not used as a PWM output can be configured as a GPIO. One FPWM in a pair can be used as a PWM output and the other pin can be used as a GPO. The FPWM pins are actively driven low from reset when used as GPOs. The frequency settings for the FPWMs apply to pairs of pins: • FPWM1 and FPWM2 – same frequency • FPWM3 and FPWM4 – same frequency • FPWM5 and FPWM6 – same frequency • FPWM7 and FPWM8 – same frequency If an FPWM pin from a pair is not used while its companion is set up to function, it is recommended to configure the unused FPWM pin as an active-low open-drain GPO so that it does not disturb the rest of the system. By setting an FPWM, it automatically enables the other FPWM within the pair if it was not configured for any other functionality. The frequency for the FPWM is derived by dividing down a 250MHz clock. To determine the actual frequency to which an FPWM can be set, must divide 250MHz by any integer between 2 and (214-1). The FPWM duty cycle resolution is dependent on the frequency set for a given FPWM. Once the frequency is known the duty cycle resolution can be calculated as Equation 1. Change per Step (%)FPWM = frequency ÷ (250 × 106 × 16) (1) Take for an example determining the actual frequency and the duty cycle resolution for a 75MHz target frequency. 1. 2. 3. 4. Divide 250MHz by 75MHz to obtain 3.33. Round off 3.33 to obtain an integer of 3. Divide 250MHz by 3 to obtain actual closest frequency of 83.333MHz. Use Equation 1 to determine duty cycle resolution to obtain 2.0833% duty cycle resolution. PWM1-4 Pins 31, 32, 41, and 42 can be used as GPIs or PWM outputs. If • • • configured as PWM outputs, then limitations apply: PWM1 has a fixed frequency of 10 kHz PWM2 has a fixed frequency of 1 kHz PWM3 and PWM4 frequencies can be 0.93 Hz to 7.8125 MHz. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 27 UCD90910 SLVSA81 – JULY 2010 www.ti.com The frequency for PWM3 and PWM4 is derived by dividing down a 15.625MHz clock. To determine the actual frequency to which these PWMs can be set, must divide 15.625MHz by any integer between 2 and (224-1). The duty cycle resolution will be dependent on the set frequency for PWM3 and PWM4. The PWM3 or PWM4 duty cycle resolution is dependent on the frequency set for the given PWM. Once the frequency is known the duty cycle resolution can be calculated as Equation 2 Change per Step (%)PWM3/4 = frequency ÷ 15.625 × 106 (2) To determine the closest frequency to 1MHz that PWM3 can be set to calculate as the following: 1. 2. 3. 4. Divide 15.625MHz by 1MHz to obtain 15.625. Round off 15.625 to obtain an integer of 16. Divide 15.625MHz by 16 to obtain actual closest frequency of 976.563kHz. Use Equation 2 to determine duty cycle resolution to obtain 6.25% duty cycle resolution. All frequencies below 238Hz will have a duty cycle resolution of 0.0015%. Programmable Multiphase PWMs The FPWMs can be aligned with reference to their phase. The phase for each FPWM is configurable from 0° to 359°. This provides flexibility in PWM-based applications such as synchronizing switch-mode power supplies, digital clock generation, and others. See an example of four FPWMs programmed to have phases at 0°, 90°, 180° and 270° (Figure 18). Figure 18. Multiphase PWMs MARGINING Margining is used in product validation testing to verify that the complete system works properly over all conditions, including minimum and maximum power-supply voltages, load range, ambient temperature range, and other relevant parameter variations. Margining can be controlled over PMBus using the OPERATION command or by configuring two GPIO pins as margin-EN and margin-UP/DOWN inputs. The MARGIN_CONFIG command in the UCD90xxx Sequencer and System Health Controller PMBus Command Reference describes different available margining options, including ignoring faults while margining and using closed-loop margining to trim the power-supply output voltage one time at power up. Open-Loop Margining Open-loop margining is done by connecting a power-supply feedback node to ground through one resistor and to the margined power supply output (VOUT) through another resistor. The power-supply regulation loop responds to the change in feedback node voltage by increasing or decreasing the power-supply output voltage to return the feedback voltage to the original value. The voltage change is determined by the fixed resistor values and the voltage at VOUT and ground. Two GPIO pins must be configured as open-drain outputs for connecting resistors from the feedback node of each power supply to VOUT or ground. 28 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 MON(1:13) 3.3V UCD90910 POWER SUPPLY 10k W GPIO(1:9) VOUT /EN 3.3V Vout VFB Rmrg_HI V BF GPIO GPIO “0” or “1” VOUT “0” or “1” Rmrg_LO 3. 3V POWER SUPPLY 10k W /EN Vout VOUT VFB VFB Rmrg_HI VOUT . 3.3V Rmrg_LO Open Loop Margining Figure 19. Open-Loop Margining Closed-Loop Margining Closed-loop margining uses a PWM or FPWM output for each power supply that is being margined. An external RC network converts the FPWM pulse train into a DC margining voltage. The margining voltage is connected to the appropriate power-supply feedback node through a resistor. The power-supply output voltage is monitored, and the margining voltage is controlled by adjusting the PWM duty cycle until the power-supply output voltage reaches the margin-low and margin-high voltages set by the user. The voltage setting resolutions will be the same that applies to the voltage measurement resolution (Table 2). The closed loop margining can operate in several modes (Table 5). Given that this closed-loop system has feed back through the ADC, the closed-loop margining accuracy will be dominated by the ADC measurement. For more details on configuring the UCD90910 for margining, see the Voltage Margining Using the UCD9012x application note (SLVA375). Table 5. Closed Loop Margining Modes Mode Description DISABLE Margining is disabled. ENABLE_TRI_STATE When not margining, the PWM pin is set to high impedance state. ENABLE_ACTIVE_TRIM When not margining, the PWM duty-cycle is continuously adjusted to keep the voltage at VOUT_COMMAND. ENABLE_FIXED_DUTY_CYCLE When not margining, the PWM duty-cycle is set to a fixed duty-cycle. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 29 UCD90910 SLVSA81 – JULY 2010 www.ti.com MON (1:13) 3.3V UCD90910 POWER SUPPLY /EN VOUT 10k W GPIO Vout VFB 250 kHz – 1MHz Vmarg FPWM1 R1 V FB R3 R4 Closed Loop Margining C1 R2 Figure 20. Closed-Loop Margining FAN CONTROL The UCD90910 can control and monitor up to ten two-, three- or four-wire fans. Up to ten GPI capable pins can be used as tachometer inputs. The number of fan tach pulses per revolution for each fan can be entered using the Fusion GUI. A fan speed-fault threshold can be set to trigger an alarm if the measured speed drops below a user-defined value. The two- and three-wire fans are controlled by connecting the positive input of the fan to the specified supply voltage for the fan. The negative input of the fan is connected to the collector or drain of a transistor. The transistor is turned off and on using a GPIO pin. Four-wire fans can be controlled the same way. However, four-wire fans should use the fan PWM input (the fourth wire). It can be driven directly by one of the eight FPWMs or the two adjustable PWM outputs. The normal frequency range for the PWM input of a typical 4-wire fan is 15 kHz to 40 kHz, but the specifications for the fan confirm the interface procedure. Temperature Temperature senso Sensor r MONx AVSS3 12V 2-Wire Fan 12V UCD90910 MOSFET turns fan on and off GND DC Fan GPIO GPIO controls MOSFET B0391-01 Figure 21. Two-Wire Fan Connection 30 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Temperature Temperature senso Sensor r MONx AVSS3 12V 3-Wire Fan 12V UCD90910 GPIO Fan Tach output to GPI/GPIO for fan speed monitoring TACH MOSFET turns fan on and off GND DC Fan GPIO GPIO controls MOSFET B0392-01 Figure 22. Three-Wire Fan Connection Temperature Temperature senso Sensor r MONx AVSS3 12V 4-Wire Fan 12V UCD90910 FPWM GPIO 15kHz to 30kHz 3.3V PWM signal changes fan speed with duty cycle 3.3V Tach output to GPI/GPIO for fan speed monitoring PWM TACH DC Fan GND B0393-01 Figure 23. Four-Wire Fan Connection The UCD90910 autocalibrate feature automatically finds and records the turn-on, turn-off and maximum speeds and duty cycles for any fan. Fans have a minimum speed at which they turn on, a turn-off speed that is usually slightly lower than the turn-on speed, and a maximum speed that occurs at slightly less than 100% duty cycle. Each speed has a PWM duty cycle that goes with it. Every fan is slightly different, even if the model numbers are the same. The built-in temperature-control algorithms use the actual measured operating speed range instead of 0 RPM to rated speed of the fan to improve the fan control algorithms. The user can choose whether to use autocalibrate or to manually enter the fan data. When configured, autocalibration will execute as soon as it is enabled and if the enable has been stored in data flash then it will occur after a device reset. Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 31 UCD90910 SLVSA81 – JULY 2010 www.ti.com The UCD90910 can control up to ten independent fans as defined in the PMBus standard. When enabled, the FAN-PWM control output provides a digital signal with a configurable frequency and duty cycle, with a duty cycle that is set based on the FAN_COMMAND_1 PMBus command. The PWM can be set to frequencies between 1 Hz and 125 MHz based on the UCD90910 PWM type selected for the fan control. The duty cycle can be set from 0% to 100% with 1% resolution. Each fan has its own ramp rate. The ramp rate is effective for any adjustments to fan speed. The ramp rate is configured by indicating the change in duty cycle per each 500 ms elapsed to reach a targeted speed. The FAN-TACH fan-control input counts the number of transitions in the tachometer output from the fan in each 1-second interval. The tachometer can be read by issuing the READ_FAN_SPEED_1 command. The speed is returned in RPMs. Fault limits can also be set for the tachometer speed by issuing the FAN_SPEED_FAULT_LIMIT command, and the status can be checked by issuing the STATUS_FAN_1_2 command. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference for a complete description of each command. The UCD90910 also supports two fan control algorithms. Hysteretic Fan Control TempON and TempOFF levels are input by the user. TempON is higher than TempOFF. A GPIO pin is used to turn the fan or fans on at full speed when the monitored temperature reaches TempON and to turn the fans off when the temperature drops below TempOFF. TOT Inputs: TON, TOFF, TOT, Update Interval, Rail where MEAS_TEMP is monitored, GPOx pin • System starts up at t = 0 seconds • MEAS_TEMP = 25°C → ambient temp • GPO/PWM is low and Fan is off • Check MEAS_TEMP every 1 second (or 250 msec) • When MEAS_TEMP = TON, set GPO/PWM = 1 → turn fan on • Leave GPO/PWM = 1 unless MEAS_TEMP < TOFF • If MEAS_TEMP is > TON, declare a fault and take the prescribed action. Temp increase above TON : Assert GPO to turn on Fan Temp drops below above TOFF : De-assert GPO to turn off Fan TON TOFF Temp drops below TON : GPO and Fan stays on (hysteresis) MEAS_TEMP 25°C (tamb) t = 0 sec 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 GPO output 0 t = 0 sec 1 MaxSpeed Fan Speed Off t = 0 sec 1 Figure 24. Hysteretic Temperature Control for 2- or 3-Wire Fans Set Point Fan Control The second algorithm (Figure 25) uses five control set points that each have a temperature and a fan speed. When the monitored temperature increases above one of the set point temperatures, the fan speed is increased to the corresponding set point value. When the monitored temperature drops below a set point temperature, the fan speed is reduced to the corresponding set point value. The ramp rate for speed can be selected, allowing the user to optimize fan performance and minimize audible noise. The ramp rate options are listed in Table 6 32 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Table 6. Fan Ramp Rate for Speed Change of Speed per Second 0.25% 0.5% 1% 2% (default) 4% 8% 16% Apply new speed immediately The fan speed is varied by changing the duty cycle of a PWM output. For two- and three-wire fans, as the fan is turned on and off, the inertia of the fan smooths out the fan speed changes, resulting in variable-speed operation. This approach can be taken with any fan, but would most likely be used with two- or three-wire fans at a PWM frequency in the 40-Hz to 80-Hz range. Four-wire fans would use the PWM input as described earlier in this section. TOT TEMP5, SPD5 TEMP4, SPD4 TEMP3, SPD3 Inputs: TOT, Updates Interval, Rail that MEAS_TEMP TEMP2, SPD2 MEAS_TEMP is being monitored on, PWM pin, PWM freq, PWM temp rate, FANTAC TEMP1, SPD1 pin, 5x (TEMPn, SPEEDn) setpoints. 25°C (T ) • System starts up at t = 0 seconds t = 0 sec 5 10 15 20 25 30 35 40 45 50 55 60 • MEAS_TEMP = 25°C at ambient temp • PWM DUTY_CYCLE = 0% and fan is off SPD5 Max Speed • Check MEAS_TEMP every 250 ms (or 1 SPD4 Fan Speed ramps down to Target Speed Target and SPD3 s) by reducing PWM Duty Cycle Ramp Speed SPD2 • When MEAS_TEMP > TEMP1: Temp rises above Fan Speed ramps up to SPD1 – set SPEED_TARGET = SPEED1 TEMP1 à Target Speed Target Speed by Temp falls below increases to SPD1 increasing PWM Duty TEMP2 à Target Speed Cycle – increase DUTY_CYCLE to decreases to SPD1 Off (SPD0) DUTY_CYCLE_ON t = 0 sec 5 10 15 20 25 30 35 40 45 50 55 60 – increase DUTY_CYCLE by ramp rate (10%/second) until SPEED = SPEED_TARGET When MEAS_TEMP > TEMP2: 100% – set SPEED_TARGET = SPEED2 – increase DUTY_CYCLE by ramp PWM duty cycle rate until SPEED = SPEED_TARGET • Repeat as temperature is increased for 0% each new setpoint t = 0 sec 5 10 15 20 25 30 35 40 45 50 55 60 • If MEAS_TEMP > TOT, declare a fault Figure 25. Temperature and Speed Set Point PWM Control for and take the prescribed action Four-Wire Fans amb Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 33 UCD90910 SLVSA81 – JULY 2010 • • www.ti.com If temperature drops - above TEMP4 to below TEMP3 for example – when MEAS_TEMP drops below TEMP4, maintain SPEED4 → do not change the DUTY_CYCLE – when MEAS_TEMP drops below TEMP3, set SPEED_TARGET = SPEED3 – decrease DUTY_CYCLE by ramp rate (10%/second) until SPEED = SPEED_TARGET To turm the fan off when MEAS_TEMP < TEMP1, set SPEED1 = 0 RPM EXAMPLE: MEAS_TEMP = 25°C at ambient temp: • t = 0 to 5 sec: MEAS_TEMP increases from ambient to TEMP1 → increases SPEED_TARGET from SPD0 (Off) to SPD1 → increases DUTY_CYCLE from 0% to DUTYON (30%) → ACTUAL fan speed ramps up from 0 RPM to SPD1. • t = 5 to 10 sec: MEAS_TEMP increases > TEMP2 → increases SPEED_TARGET from SPD1 to SPD2 → increases DUTY_CYCLE → ACTUAL fan speed ramps up from SPD1 to SPD2. • t = 10 to 25 sec: MEAS_TEMP increases to > TEMP5 → SPEED_TARGET increases from SPD2 to SPD5 → DUTY_CYCLE ramps to DUTYMAX → ACTUAL fan speed increases SPD5. • t = 25 to 30 sec: MEAS_TEMP stays > TEMP5 → SPEED_TARGET and DUTY_CYCLE do not change → ACTUAL fan speed stays at SPD5. • t = 30 to 35 sec: MEAS_TEMP decreases to < TEMP4 → SPEED_TARGET drops to SPD4 and then to SPD3 → decreases DUTY_CYCLE → ACTUAL fan speed ramps down from SPD5 to SPD3. • t = 35 to 60 sec: MEAS_TEMP decreases to < TEMP1 → SPEED_TARGET drops to SPD0 → decreases DUTY_CYCLE to DUTYOFF → ACTUAL fan speed ramps down from SPD3 to SPD0 (Off). SYSTEM RESET SIGNAL The UCD90910 can generate a programmable system-reset signal as part of sequence-on. The signal is created by programming a GPIO to remain deasserted until the voltage of a particular rail or combination of rails reach their respective POWER_GOOD_ON levels plus a programmable delay time Figure 26. The system-reset delay duration can be programmed as shown in Table 7. GPI states and Watchdog Timeouts can also be used to define the System Reset behavior. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference for complete definitions of SYSTEM_RESET_CONFIG command. PMBUS_CNTRL PIN RAIL 1 EN TON_DELAY[1] POWER_GOOD_ON[1] POWER_GOOD_ON[1] RAIL 1 VOLTAGE RAIL 2 EN RAIL 2 VOLTAGE POWER_GOOD_OFF[1] TON_DELAY[2] POWER_GOOD_ON[2] POWER_GOOD_OFF[2] DELAY TIME DELAY TIME GPO SET AS SYSTEM RESET Figure 26. System Reset Timing Example Table 7. System-Reset Delay Time Delay Time 0 ms 34 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 UCD90910 www.ti.com SLVSA81 – JULY 2010 Table 7. System-Reset Delay Time (continued) Delay Time 1 ms 2 ms 4 ms 8 ms 16 ms 32 ms 64 ms 128 ms 256 ms 512 ms 1.02 s 2.05 s 4.10 s 8.19 s 16.38 s 32.8 s WATCHDOG TIMER A GPI and GPO can be configured as a watchdog timer (WDT). The WDT can be independent of power-supply sequencing or tied to a GPIO functioning as a watchdog output (WDO) that is configured to provide a system-reset signal. The WDT can be reset by toggling a watchdog input (WDI) pin or by writing to SYSTEM_WATCHDOG_RESET over I2C. The WDI and WDO pins are optional when using the watchdog timer. The WDI can be replaced by SYSTEM_WATCHDOG_RESET command and the WDO can be manifested through the Boolean Logic defined GPOs or through the System Reset function. The WDT can be active immediately at power up or set to wait while the system initializes. Table 8 lists the programmable wait times before the initial time-out sequence begins. Table 8. WDT Initial Wait Time WDT INITIAL WAIT TIME 0 ms 100 ms 200 ms 400 ms 800 ms 1.6 s 3.2 s 6.4 s 12.8 s 25.6 s 51.2 s 102 s 205 s 410 s 819 s 1638 s Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated Product Folder Link(s) :UCD90910 35 UCD90910 SLVSA81 – JULY 2010 www.ti.com The watchdog time-out is programmable from 0 to 2.55 s with a 10-ms step size. If the WDT times out, the UCD90910 can assert a GPIO pin configured as WDO that is separate from a GPIO defined as system-reset pin, or it can generate a system-reset pulse. After a time-out, the WDT is restarted by toggling the WDI pin or by writing to SYSTEM_WATCHDOG_RESET over I2C. WDI