TPS929121AQPWPRQ1

TPS929121-Q1 TPS929121-Q1 SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 www.ti.com TPS929121-Q1 12-Channel Automotive 40-V High-Side LED Driver With FlexWire 1 Features 2 Applications • • • • • • • • AEC-Q100-qualified for automotive applications: – Temperature grade 1: –40°C to +125°C, TA 12-channel precision high-side current output: – Supply voltage 4.5 V to 40 V – Up to 75-mA channel current set by resistor – 2-bit global, 6-bit independent current setting – High current accuracy < ±5% at 5 mA to 75 mA – High current accuracy < ±10% at 1 mA – Low voltage drop 500 mV at 50 mA – 12-bit independent PWM dimming – Programmable PWM frequency up to 20 kHz – Linear and exponential dimming method FlexWire control interface – Up to 1-MHz clock frequency – Maximum 16 devices on one FlexWire bus – Up to 8-bytes data transaction in one frame – 5-V LDO output to supply CAN transceiver Diagnostic and protection: – Programmable fail-safe state – LED open-circuit detection – LED short-circuit detection – Single-LED short-circuit diagnostic – Programmable low-supply detection – Open-drain ERR for fault indication – Watchdog and CRC for FlexWire interface – 8-Bit ADC for pin voltage measurement – Overtemperature protection Automotive exterior rear light Automotive exterior headlight Automotive interior ambient light Automotive cluster display 3 Description With increasing demand for animation in automotive lighting, LEDs must be controlled independently. Therefore, LED drivers with digital interfaces are essential to effectively drive pixel-controlled lighting applications. In exterior lighting, multiple lamp functions are typically located on different PCB boards with off-board wires connected to each other. It is difficult for a traditional single-ended interface to meet the strict EMC requirements. By using an industrialstandard CAN physical layer, the UART-based FlexWire interface of the TPS929121-Q1 easily accomplishes long distance off-board communication without impacting EMC. The TPS929121-Q1 is a 12-channel, 40-V high-side LED driver that controls the 8-bit output current and 12-bit PWM duty cycles. The device meets multiple regulation requirements with LED open-circuit, shortto-ground, and single LED short-circuit diagnostics. A configurable watchdog also automatically sets failsafe states when the MCU connection is lost, and, with programmable EEPROM, TPS929121-Q1 can flexibly be set for different application scenarios. Device Information (1) PART NUMBER TPS929121-Q1 (1) CANH CANL TPS929121-Q1 RX RX CAN Transceiver (optional) VLDO OUT10 GND OUT9 TX TX OUT8 ERR OUT7 SUPPLY OUT6 SUPPLY OUT5 FS OUT4 ADDR2/CLK OUT3 ADDR1/PWM1 OUT2 ADDR0/PWM0 OUT1 REF OUT0 PACKAGE HTSSOP (24) BODY SIZE (NOM) 7.80 mm × 4.40 mm For all available packages, see the orderable addendum at the end of the data sheet. OUT11 GND Typical Application Diagram An©IMPORTANT NOTICEIncorporated at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, Copyright 2021 Texas Instruments Submit Document Feedback intellectual property matters and other important disclaimers. PRODUCTION DATA. Product Folder Links: TPS929121-Q1 1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 Table of Contents 1 Features............................................................................1 2 Applications..................................................................... 1 3 Description.......................................................................1 4 Revision History.............................................................. 2 5 Device Comparison Table...............................................3 6 Pin Configuration and Functions...................................4 7 Specifications.................................................................. 5 7.1 Absolute Maximum Ratings ....................................... 5 7.2 ESD Ratings .............................................................. 5 7.3 Recommended Operating Conditions ........................5 7.4 Thermal Information ...................................................6 7.5 Electrical Characteristics ............................................6 7.6 Timing Requirements ................................................. 8 7.7 Typical Characteristics................................................ 9 8 Detailed Description......................................................14 8.1 Overview................................................................... 14 8.2 Functional Block Diagram......................................... 15 8.3 Feature Description...................................................15 8.4 Device Functional Modes..........................................33 8.5 Programming............................................................ 37 8.6 Register Maps...........................................................45 9 Application and Implementation................................ 154 9.1 Application Information........................................... 154 9.2 Typical Application.................................................. 154 10 Power Supply Recommendations............................158 11 Layout......................................................................... 158 11.1 Layout Guidelines................................................. 158 11.2 Layout Example.................................................... 158 12 Device and Documentation Support........................159 12.1 Receiving Notification of Documentation Updates159 12.2 Support Resources............................................... 159 12.3 Trademarks........................................................... 159 12.4 Electrostatic Discharge Caution............................159 12.5 Glossary................................................................159 13 Mechanical, Packaging, and Orderable Information.................................................................. 159 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision * (December 2020) to Revision A (February 2021) Page • Changed status from "Advance Information" to "Production Data".....................................................................1 2 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 5 Device Comparison Table TPS929120QPWPRQ1 TPS929120AQPWPRQ1 TPS929121QPWPRQ1 ADC coverage up to 20 V V(ADCLOWSUPTH) = 5 V to 20 V EEP_DEVADDR[3]=0 (default) TPS929121AQPWPRQ1 ADC coverage up to 40 V V(ADCLOWSUPTH) = 10 V to 40 V EEP_DEVADDR[3]=1 (default) EEP_DEVADDR[3]=0 (default) EEP_DEVADDR[3]=1 (default) Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 3 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 6 Pin Configuration and Functions RX 1 24 OUT11 VLDO 2 23 OUT10 GND 3 22 OUT9 TX 4 21 OUT8 ERR 5 20 OUT7 SUPPLY 6 19 OUT6 SUPPLY 7 18 OUT5 FS 8 17 OUT4 ADDR2/CLK Thermal Pad 9 16 OUT3 ADDR1/PWM1 10 15 OUT2 ADDR0/PWM0 11 14 OUT1 REF 12 13 OUT0 Not to scale Figure 6-1. PWP Package 24-Pin HTSSOP With PowerPAD™ Top View Table 6-1. Pin Functions PIN NO. I/O DESCRIPTION 1 RX I 2 VLDO Power 3 GND GND 4 TX O FlexWire TX. 5 ERR I/O Open-drain error output. SUPPLY Power 8 FS I Fail-safe state selection. 0: Fail-safe state 0; 1: Fail-safe state 1. 9 ADDR2/CLK I Function as device address 2 in external address mode; Function as PWM clock input internal address mode when CONF_EXTCLK is 1. 10 ADDR1/ PWM1 I Function as device address 1 in external address mode; Function as PWM input channel for OUT6-11 in internal address mode. 11 ADDR0/ PWM0 I Function as device address 0 in external address mode; Function as PWM input channel for OUT0-5 in internal address mode. 12 REF I/O Device reference current setting, EEPROM programming chip-selection input. 13 OUT0 O Output channel 0. 14 OUT1 O Output channel 1. 15 OUT2 O Output channel 2. 16 OUT3 O Output channel 3. 17 OUT4 O Output channel 4. 18 OUT5 O Output channel 5. 19 OUT6 O Output channel 6. 20 OUT7 O Output channel 7. 21 OUT8 O Output channel 8. 22 OUT9 O Output channel 9. 23 OUT10 O Output channel 10. 24 OUT11 O Output channel 11. 6, 7 4 NAME FlexWire RX. 5-V regulator output. Device ground. Power supply. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted)(1) MIN MAX UNIT SUPPLY Device supply voltage –0.3 45 V FS High-voltage input –0.3 V(SUPPLY) + 0.3 V OUT0 - 11 High-voltage outputs –0.3 V(SUPPLY) + 0.3 V ERR High-voltage output –0.3 22 V ADDR2/CLK, ADDR1/PWM1, Low-voltage input ADDR0/PWM0, REF, RX –0.3 5.5 V VLDO, TX Low-voltage output –0.3 5.5 V TJ Junction temperature –40 150 °C Tstg Storage temperature –65 150 °C (1) Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Condition. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 7.2 ESD Ratings VALUE Human body model (HBM), per AEC V(ESD) (1) Electrostatic discharge Charged device model (CDM), per AEC Q100-011 Q100-002(1) ±2000 Corner pins (RX, REF, OUT0, OUT11) ±750 Other pins ±500 UNIT V AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification. 7.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN NOM MAX UNIT SUPPLY Device supply voltage 4.5 36 V IOUT0-IOUT11 Channel output current FS External fail-safe selection input 0.5 75 mA 0 V(SUPPLY) V TX RX FlexWire TX output 0 5 V FlexWire RX input 0 5 V VLDO Internal 5V LDO output 0 5 V I(VLDO) LDO external current load 0 80 mA ADDR2/CLK, ADDR1/ PWM1, ADDR0/ Device address selection and external CLK/PWM inputs PWM0 0 5 V REF Current reference setting 0 5 V ERR Error feedback open-drain output 0 20 V t(r_RX) RX risetime 5%/fCLK t(f_RX) RX falltime fCLK FlexWire frequency 5%/fCLK DSYNC Synchronization pulse dutycycle TA Ambient temperature 10 45 –40 1000 50 kHz 55 % 125 °C Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 5 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.3 Recommended Operating Conditions (continued) over operating free-air temperature range (unless otherwise noted) MIN TJ Junction temperature NOM –40 MAX UNIT 150 °C 7.4 Thermal Information TPS929121-Q1 THERMAL METRIC(1) HTSSOP (PWP) UNIT 24 PINS RθJA Junction-to-ambient thermal resistance 35 °C/W RθJC(top) Junction-to-case (top) thermal resistance 26.1 °C/W RθJB Junction-to-board thermal resistance 13.7 °C/W ΨJT Junction-to-top characterization parameter 0.4 °C/W ΨJB Junction-to-board characterization parameter 13.6 °C/W RθJC(bot) Junction-to-case (bottom) thermal resistance 2.4 °C/W (1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. 7.5 Electrical Characteristics TJ = –40°C to 150°C, V(SUPPLY) = 5-40 V, For digital outputs, C(LOAD) = 20 pF, (unless otherwise noted). PARAMETER TEST CONDITIONS MIN TYP MAX 4.5 12 UNIT BIAS V(SUPPLY) Operating input voltage IQ(ON) Quiescent current, all-channels-on V(SUPPLY) = 12 V, R(REF) =31.6 kΩ, alloutput ON IQ(OFF) Quiescent current, all-channels-off V(SUPPLY) = 12 V, R(REF) = 31.6 kΩ, alloutput OFF I(FAULT) Quiescent current, fail-safe state fault mode V(SUPPLY) = 12 V, fail-safe state, alloutput OFF, ERR = LOW 2.5 40 V 10 mA 3.5 mA 2.85 mA V(POR_rising) Power-on-reset rising threshold 4 4.2 4.4 V V(POR_falling) Power-on-reset falling threshold 3.8 4 4.2 V V(SUPPLY) > 5.6 V, I(LDO) = 40 mA, CONF_LDO = 0b 4.75 5 5.25 V V(SUPPLY) > 5.6 V, I(LDO) = 40 mA, CONF_LDO = 1b 4.18 4.4 4.62 V V(LDO) LDO output voltage I(LDO) LDO output current capability I(LDO_LIMIT) LDO output current limit 80 V(LDO_DROP) LDO maximum dropout voltage I(LDO) = 80 mA 0.5 0.9 V V(LDO_DROP) LDO maximum dropout voltage I(LDO) = 50 mA 0.3 0.6 V 100 mA mA V(LDO_POR_rising) LDO power-on-reset rising threshold 2.75 3 3.25 V V(LDO_POR_falling) LDO power-on-reset falling threshold 2.5 2.75 3 V C(LDO) Supported LDO loading capacitance range 1 10 µF f(OSC) Internal oscillator frequency -2.5% 32.15 +2.5% MHz ERR VIL(ERR) 6 Input logic low voltage, ERR 0.7 VIH(ERR) Input logic high voltage, ERR I(pd_ERR) ERR pull-down current capability 2 V(ERR) = 0.4 V Submit Document Feedback 3 V V 6 9 mA Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.5 Electrical Characteristics (continued) TJ = –40°C to 150°C, V(SUPPLY) = 5-40 V, For digital outputs, C(LOAD) = 20 pF, (unless otherwise noted). PARAMETER Ilkg(ERR) TEST CONDITIONS MIN TYP ERR leakage current MAX UNIT 1 µA 0.7 V FLEXWIRE INTERFACE VIL(RX) Input logic low voltage, RX VIH(RX) Input logic high voltage, RX VOL(TX) Low-level output voltage TX, Isink = 5 mA, 2 VOH(TX) High-level output voltage TX, Isource = 5 mA, Vpull-up = 5 V Ilkg TX, RX V 0 0.3 V 4.7 5 V –1 1 µA 0.7 V ADDRESS, FS VIL(IO) Input logic low voltage, ADDR2/CLK, ADDR1/PWM1, ADDR0/PWM0, FS VIH(IO) Input logic high voltage, ADDR2/CLK, ADDR1/PWM1, ADDR0/PWM0, FS R(PD_ADDR) Internal pull down resistance, ADDR2/ CLK, ADDR1/PWM1, ADDR0/PWM0 100 kΩ R(PD_FS) Internal pull down resistance, FS 100 kΩ 2 V ADC DNL Differential nonlinearity –1(1) 1(1) LSB INL Integral nonlinearity –2(1) 2(1) LSB OUTPUT DRIVERS f(PWM_200) 200-Hz selection f(PWM_1000) 1-kHz selection ΔI(OUT_d2d) ΔI(OUT_c2c) Device-to-device accuracy ΔI(OUT_d2d) = 1- Iavg(OUT) / Iideal(OUT) Channel-to-channel accuracy ΔI(OUT_c2c) = 1- I(OUTx) / Iavg(OUT) 200 Hz 1000 Hz R(REF) = 8.45 kOhm, CONF_REFRANGE = 11b, DC=63 –5 0 5 R(REF) = 8.45 kOhm, CONF_REFRANGE = 10b, DC=63 –5 0 5 R(REF) = 8.45 kOhm, CONF_REFRANGE = 01b, DC=63 –5 0 5 R(REF) = 8.45 kOhm, CONF_REFRANGE = 00b, DC=63 –5 0 5 R(REF) = 8.45 kOhm, CONF_REFRANGE = 11b, DC=63 –3 0 3 R(REF) = 8.45 kOhm, CONF_REFRANGE = 10b, DC=31 –3 0 3 R(REF) = 8.45 kOhm, CONF_REFRANGE = 01b, DC=15 –5 0 5 R(REF) = 31.6 kOhm, CONF_REFRANGE = 01b, DC=12 –7 0 7 % % I(OUT_75mA) R(REF) = 8.45 kOhm, CONF_REFRANGE = 11b, DC=63 75 mA I(OUT_50mA) R(REF) = 12.7 kOhm, CONF_REFRANGE = 11b, DC=63 50 mA I(OUT_20mA) R(REF) = 31.6 kOhm, CONF_REFRANGE = 11b, DC=63 20 mA I(OUT_1mA) R(REF) = 31.6 kOhm, CONF_REFRANGE = 01b, DC = 12 1 mA V(OUT_drop) output dropout voltage R(REF) = 8.45 kOhm, CONF_REFRANGE = 11b, DC=38, I(OUTx) = 45 mA 400 700 mV Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 7 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.5 Electrical Characteristics (continued) TJ = –40°C to 150°C, V(SUPPLY) = 5-40 V, For digital outputs, C(LOAD) = 20 pF, (unless otherwise noted). PARAMETER V(OUT_drop) TEST CONDITIONS MIN R(REF) = 8.45 kOhm, CONF_REFRANGE = 11b, DC=63, I(OUTx) = 75 mA output dropout voltage TYP MAX UNIT 600 1000 mV R(REF) 1 50 kΩ C(REF) 0 4.7 nF V(REF) 1.235 K(REF_11) CONF_REFRANGE = 11b 512 K(REF_10) CONF_REFRANGE = 10b 256 K(REF_01) CONF_REFRANGE = 01b 128 K(REF_00) CONF_REFRANGE = 00b 64 V I(REF_OPEN_th) 10 µA V(REF_SHORT_th) 0.6 V DIAGNOSTICS V(OPEN_th_rising) LED open rising threshold V(SUPPLY) - V(OUTx) 200 400 600 mV V(OPEN_th_falling) LED open falling threshold V(SUPPLY) - V(OUTx) 300 500 700 mV V(OPEN_th_hyst) 100 mV V(SG_th_rising) Short-to-ground rising threshold 0.8 0.9 1 V V(SG_th_falling) Short-to-ground falling threshold 1.1 1.2 1.3 V V(SG_th_hyst) Short-to-ground hysteresis 0.3 V 135 oC 5 oC EEPROM N(EEP) Number of programming cycles. V(SUPPLY) = 12 V 1000 MISC T(PRETSD) Pre-thermal warning threshold T(PRETSD_HYS) Pre-thermal warning hysteresis T(TSD) Over-temperature protection threshold T(TSD_HYS) Over-temperature protection hysteresis (1) 160 175 190 oC oC 15 Guaranteed by design only 7.6 Timing Requirements MIN 8 NOM MAX UNIT t(ODPW) Diagnostics pulse-width, CONF_ODPW = 0h 100 µs t(CONV) time needed to complete one AD conversion 57 µs t(OPEN_deg) Open-circuit deglitch timer 5 µs t(SHORT_deg) Short-circuit deglitch timer 5 µs t(retry) Fault retry timer 10 ms Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.7 Typical Characteristics 4 7.2 Supply Standby Current (mA) 3.5 Fault Current (mA) 7.4 TA = 25 oC TA = 125 oC TA = 40 oC 3 2.5 2 1.5 7 6.8 6.6 6.4 6.2 6 5.8 1 5.6 0 5 10 15 20 25 Supply Voltage (V) 30 35 40 0 10 20 30 D001 40 50 60 70 REF Resistor (k:) 80 90 100 D002 R(REF) = 8.35 kΩ CONF_REFRANGE[1:0] = 3h CONF_REFRANGE[1:0] = 3h 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 Figure 7-2. Standby Current vs REF Resistor 105 TA = 25 oC TA = 125 oC TA = 40 oC I(OUT) = 5 mA I(OUT) = 50 mA I(OUT) = 75 mA 90 Output Current (mA) Output Current (mA) Figure 7-1. Fault Current vs Supply Voltage 75 60 45 30 15 0 0 10 20 30 40 50 60 70 REF Resistor (k:) 80 90 100 0 0.5 1 D003 1.5 2 2.5 Dropout Voltage (V) 3 3.5 4 D004 CONF_IOUTx[5:0] = 3Fh CONF_REFRANGE[1:0] = 3h CONF_REFRANGE[1:0] = 3h Figure 7-3. Output Full-range Current vs REF Resistor 80 105 TA = 25 oC TA = 125 oC TA = 40 oC 70 I(OUT) = 5 mA I(OUT) = 50 mA I(OUT) = 75 mA 90 60 Output Current (mA) Output Current (mA) Figure 7-4. Output Current vs Dropout Voltage 50 40 30 20 75 60 45 30 15 10 0 0 0 0.5 1 1.5 2 2.5 Dropout Voltage (V) 3 3.5 4 0 5 D005 10 15 20 25 Supply Voltage (V) 30 35 40 D006 R(REF) = 12.6 kΩ CONF_IOUTx[5:0] = 3Fh CONF_REFRANGE[1:0] = 3h Figure 7-5. Output Current vs Dropout Voltage Figure 7-6. Output Current vs Supply Voltage Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 9 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.7 Typical Characteristics 100 70 I(OUT) = 75 mA TA = 25 oC I(OUT) = 50 mA TA = 25 oC I(OUT) = 75 mA TA = 125 oC I(OUT) = 50 mA TA = 125 oC I(OUT) = 75 mA TA = 40 oC I(OUT) = 50 mA TA = 40 oC 90 60 80 Output Current (mA) Output Average Current (mA) I(OUT) = 50 mA 50 40 30 20 70 60 50 40 30 20 10 10 0 0 32 64 96 128 160 PWMOUT[7:0] 192 224 0 256 0 8 16 24 D007 R(REF) = 12.6 kΩ R(REF) = 8.35 kΩ & 12.6 kΩ CONF_IOUTx[5:0] = 3Fh CONF_REFRANGE[1:0] = 3h Figure 7-7. Average Current vs PWMOUT[7:0] 6 64 D008 5.08 5.4 5.2 5 4.8 4.6 5.06 5.04 5.02 5 4.98 4.96 4.4 4.94 4.2 4.92 4 4.9 0 5 10 15 20 25 Supply Voltage (V) 30 35 40 Ch1 = V(SUPPLY) Ch3 = V(OUT0) 0 10 D009 Figure 7-9. LDO Output Line Regulation Ch6 = I(OUT0) Figure 7-11. PWM Dimming at 200 Hz 10 56 5.1 LDO Output Voltage (V) LDO Output Voltage (V) 5.6 48 Figure 7-8. Output DC Current vs IOUT[5:0] TA = 25 oC TA = 125 oC TA = 40 oC 5.8 32 40 IOUT[5:0] 20 30 40 50 60 LDO Output Current (mA) 70 80 D010 Figure 7-10. LDO Output Load Regulation Ch1 = V(SUPPLY) Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-12. PWM Dimming at 2000 Hz Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.7 Typical Characteristics (continued) Ch1 = V(SUPPLY) Ch3 = V(OUT0) Ch6 = I(OUT0) Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-13. Supply Dimming In Fail-Safe Mode Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-14. Transient Undervoltage Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-15. Transient Overvoltage Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-16. Jump Start Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT0) Ch6 = I(OUT0) Figure 7-17. Superimposed Alternating Voltage 15 Hz Figure 7-18. Superimposed Alternating Voltage 1 kHz Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 11 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.7 Typical Characteristics (continued) Ch1 = V(SUPPLY) Ch2 = ERR Ch4 = V(LDO) Ch6 = I(OUT0) Ch3 = V(OUT0) Figure 7-19. Slow Decrease and Quick Increase of Supply Voltage Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(LDO) Ch4 = V(LDO) 0 to 80 mA Figure 7-21. LDO Output Load Transient Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT0) T(ODPW) = 100 µs Ch3 = V(OUT0) F(PWM) = 2 kHz Ch1 = V(SUPPLY) Ch2 = ERR Ch4 = V(LDO) Ch6 = I(OUT0) Ch3 = V(OUT0) Figure 7-20. Slow Decrease and Slow Increase of Supply Voltage Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT0) T(ODPW) = 100 µs Ch3 = V(OUT0) F(PWM) = 2 kHz Figure 7-22. LED Open-Circuit Detection In Normal Mode Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT5) T(ODPW) = 100 µs Ch3 = V(OUT5) F(PWM) = 2 kHz V(ADCSHORTTH) = 4 V Figure 7-23. LED Short-Circuit Detection In Normal Mode 12 Figure 7-24. Single-LED Short-Circuit Detection In Normal Mode Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 7.7 Typical Characteristics (continued) Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT0) T(ODPW) = 100 µs Ch3 = V(OUT5) F(PWM) = 2 kHz Figure 7-25. LED Open-Circuit Detection In FS Mode Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT0) T(ODPW) = 100 µs Ch3 = V(OUT5) F(PWM) = 2 kHz Figure 7-27. LED Short-Circuit Detection In Fail-Safe Mode Ch1 = V(SUPPLY) Ch2 = ERR Ch3 = V(OUT5) Ch6 = I(OUT0) T(ODPW) = 100 µs F(PWM) = 2 kHz Figure 7-26. LED Open-Circuit Recovery In FS Mode Ch1 = V(SUPPLY) Ch2 = ERR Ch6 = I(OUT0) T(ODPW) = 100 µs Ch3 = V(OUT5) F(PWM) = 2 kHz Figure 7-28. LED Short-Circuit Recovery In Fail-Safe Mode Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 13 TPS929121-Q1 SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 www.ti.com 8 Detailed Description 8.1 Overview TPS929121-Q1 is an automotive 12-channel LED driver with FlexWire interface to address increasing requirements for individual control of each LED string. Each of its channel can support both analog dimming and pulse-width-modulation (PWM) dimming, configured through its FlexWire serial interface. The internal electrically erasable programmable read-only memory (EEPROM) allows users to configure device in the scenario of communication loss to fulfill system level safety requirements. The FlexWire interface is a robust address-based master-slave interface with flexible baud rate. The interface is based on multi-frame universal asynchronous receiver-transmitter (UART) protocol. The unique synchronization frame of FlexWire reduces system cost by saving external crystal oscillators. It also supports various physical layer with the help of external physical layer transceiver such as CAN or LIN transceivers. The embedded CRC correction is able to ensure robust communication in automotive environments. The FlexWire interface is easily supported by most MCUs in the markets. Each output is a constant current source with individually programmable current output and PWM duty cycle. Each channel features various diagnostics including LED open-circuit, short-circuit and single-LED short-circuit detection. The on-chip analog-digital convertor (ADC) allows controller to real-time monitor loading conditions. To further increase robustness, the unique fail-safe of the device state machine allows automatic switching to fail-safe states in the case of communication loss, for example, MCU failure. The device supports programming fail-safe settings with user-programmable EEPROM. In fail-safe states, the device supports different configurations if output fails, such as one-fails-all-fail or one-fails-others-on. Each channel can be independently programmed as on or off in fail-safe states. The fail-safe state machine also allows the system to function with pre-programmed EEPROM settings without presence of any controller in the system, also known as stand-alone operation. The microcontroller can access each of the device through the FlexWire interface. By setting and reading back the registers, the master, which is the microcontroller, has full control over the device and LEDs. All EEPROMs are pre-programmed to default values. TI recommends that users program the EEPROM at the end-of-line for application-specific settings and fail-safe configurations. 14 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 8.2 Functional Block Diagram TPS929121-Q1 SUPPLY FS REF Bias 12-Ch Output VLDO ERR OUT 11 - 0 Error Feedback Diagnostics TX Digital Core FlexWire Interface RX ADC ADDR2 / CLK GND EEPROM ADDR1 / PWM1 Device Address ADDR0 / PWM0 Fail-Safe Statemachine 8.3 Feature Description 8.3.1 Device Bias and Power 8.3.1.1 Power Supply (SUPPLY) The TPS929121-Q1 is AECQ-100 qualified for automotive applications. The power input to the device through SUPPLY pin can be low to 4.5 V and up to 40 V for automotive battery directly powered systems. 8.3.1.2 5-V Low-Drop-Out Linear Regulator (VLDO) The TPS929121-Q1 has an integrated low-drop-out linear regulator to provide power supply to external CAN transceivers, such as TCAN1042. The internal LDO powered by supply voltage V(SUPPLY) provides a stable 5-V output with up to 80-mA constant current capability. TI recommends a ceramic capacitor from 1 µF to 10 µF on the VLDO pin. The LDO has an internal current limit I(LDO_LIMIT) for protection and soft start. The capacitor charging time must be considered to total start-up time period, because the device is held in POR state if the capacitor voltage is not charged to above UVLO threshold. 8.3.1.3 Undervoltage Lockout (UVLO) and Power-On-Reset (POR) In order to ensure clean start-up, the TPS929121-Q1 uses UVLO and POR circuitry to clear its internal registers upon power-up and to reset registers with its default values. The TPS929121-Q1 has internal UVLO circuits so that when either power supply voltage V(SUPPLY) or LDO output voltage V(LDO) is lower than its UVLO threshold, POR is triggered. In POR state, the device resets digital core and all registers to default value. FLAG_POR register is set to 1 for each POR cycle to indicate the POR history. Before both powers are above UVLO thresholds, the TPS929121-Q1 stays in POR state with all outputs off and ERR pulled down. Once both power supplies are above UVLO threshold, the device enters INIT mode for initialization releasing ERR pulldown. A programmable timer starts counting in INIT state, the timer length can be set by EEPROM register EEP_INITTIMER. When the timer is completed, the device switches to normal state. In INIT state, setting CLR_POR to 1 clears FLAG_POR, disables the timer, and sets the device to normal state. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 15 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 Upon powering up, the TPS929121-Q1 automatically loads all settings stored in EEPROM to correlated registers and sets the other registers to default value which don't have correlated EEPROM. All channels are powered up in off-state by default to avoid unwanted blinking. Writing 1 to CLR_REG manually loads EEPROM setting to the correlated registers and set the other registers to default value. After CLR_REG is set, the FLAG_POR is set 1 to indicate registers clear to default values. Writing 1 to CLR_POR resets the FLAG_POR register to 0. TI recommends settting CLR_REG to 1 to clear the internal registers every time after POR. The CLR_REG automatically resets to 0. 8.3.1.4 Programmable Low Supply Warning The TPS929121-Q1 uses its internal ADC to monitor supply voltage V(SUPPLY). If the supply is below allowable working threshold, the output voltage may not be sufficient to keep the LED operating with desired brightness output as expected. The ADC output is automatically compared with threshold set by register CONF_ADCLOWSUPTH as described in Register Maps. When the supply voltage is below threshold, the device sets warning flag register FLAG_ADCLOWSUP to 1 in the status register. CLR_FAULT is able to clear the FLAG_ADCLOWSUP as well as other fault registers. In addition, the LED open-circuit and single LED shortcircuit detection is disabled if the supply voltage is below threshold to avoid LED open circuit and to prevent the single LED short-circuit fault from being mis-triggered. The 4-bit register CONF_ADCLOWSUPTH has total 15 options covering from 5 V to 20 V. 8.3.2 Constant Current Output 8.3.2.1 Reference Current With External Resistor (REF) The TPS929121-Q1 must have an external resistor R(REF) to set the internal current reference I(REF) as shown in Figure 8-1. CONF_REFRANGE[1:0] 2-bit range selection K(REF) CONF_IOUT0[5:0] I(FULL_RANGE) ×512 OUT0 6-bit DAC CH0 CONF_IOUT1[5:0] ×256 ×128 OUT1 6-bit DAC ×64 CH1 Optional CREF REF V(REF) 1.235V Vbg 1.235V CONF_IOUT11[5:0] OUT11 6-bit DAC RREF CH11 Figure 8-1. Output Current Setting The internal current reference I(FULL_RANGE) is generated based on the I(REF) multiplied by factor K(REF) to provide the full range current reference for each OUTx channel. The K(REF) is programmable by 2-bit register CONF_REFRANGE with 4 different options. The I(FULL_RANGE) can be calculated with Equation 1. I(FULL _ RANGE) V(REF) R(REF) u K(REF) (1) where • • 16 V(REF) = 1.235 V typically K(REF) = 64, 128, 256, or 512 (default) Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 The recommended resistor values of R(REF) and amplifier ratios of K(REF) are listed in Table 8-1. Table 8-1. Reference Current Range Setting CONF_REFRA NGE K(REF) 11b 512 FULL RANGE CURRENT (mA) R(REF) = 8.45 kΩ R(REF) = 12.7 kΩ R(REF) = 31.6 kΩ 75 50 20 10b 256 37.5 25 10 01b 128 18.75 12.5 5 00b 64 9.375 6.25 2.5 Place the R (REF) resistor as close as possible to the REF pin with an up to 2.2-nF ceramic capacitor in parallel to improve the noise immunity. The off-board R(REF) setup is not allowed due to the concern of instability reference current. TI recommends a 1-nF ceramic capacitor in parallel with R(REF). 8.3.2.2 64-Step Programmable High-Side Constant-Current Output TPS929121-Q1 has 12 channels of high-side current sources. Each channel has its own enable configuration register CONF_ENCHx. Setting CONF_ENCHx to 1 enables the channel output; clearing the register to 0 disables the channel output. To completely turn off the channel current, user can clear channel enable bit CONF_ENCHx to 0. Upon power up, CONF_ENCHx is automatically reset to 0 to avoid unwanted blinking. Each OUTx channel supports individual 64-step programmable current setting, also known as dot correction (DC). The DC feature can be used to set binning values for output LEDs or to calibrate the LEDs to achieve high brightness homogeneity based on external visual system to further save binning cost. The 6-bit register CONF_IOUTx sets the current independently, where x is the channel number from 0 to 11. The OUTx current can be calculated with Equation 2. I(OUTx) (CONF _IOUTx 1) u I(FULL _ RANGE) 64 (2) where • • • CONF_IOUTx is programmable from 0 to 63. x is from 0 to 11 for different output channel. I(FULL_RANGE) can be calculated with Equation 1. 8.3.3 PWM Dimming TPS929121-Q1 integrates independent 12-bit PWM generators for each OUTx channel. The current output for each OUTx channel is turned on and off controlled by the integrated PWM generator. The average current of each OUTx can be adjusted by PWM duty cycle independently, therefore, to control the brightness for LEDs in each channel. 8.3.3.1 PWM Dimming Frequency The frequency for PWM dimming is programmable by 4-bit register CONF_PWMFREQ with 16 options covering from 200 Hz to 20.8 kHz. Select the frequency for PWM dimming based on the minimum brightness requirement in application. TPS929121-Q1 supports down to 1-µs minimum pulse current for all 12-channel outputs. 8.3.3.2 PWM Generator The 12-bit PWM generator constructs the cyclical PWM output based on a 12-bit digital binary input to control the output current ON and OFF. Basically the PWM generator counts 256 pulses at base high frequency for PWM output cycle period and counts number of pulses determined by MSB 8 bits of 12-bit binary input at the same frequency for PWM ON period. The LSB 4 bits of 12-bit binary input is used to set up the dithering to realize total 12-bit resolution. The base high frequency is generated by internal oscillator, which is 256 times of the frequency programmable by CONF_PWMFREQ. Figure 8-2 is the signal path diagram for PWM generator. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 17 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 ADDR0/PWM0 CH5-CH0 NAND 6 EEP_INTADDR 1: INT ADDR 0: EXT ADDR ADDR1/PWM1 12 CH11-CH6 NAND 6 CONF_EXPEN 1: LUT EN 0: LUT DIS Exponential Look-Up Table CONF_PWMOUTx[7:0] 8 1 8 12 MUX 8 12 Linear 12 CONF_PWMLOWOUTx[3:0] PWMOUT 12-bit PWM Generator 0 CONF_EXTCLK EEP_INTADDR 1: EXT CLK 1: INT ADDR 0: INT CLK 0: EXT ADDR AND 12 12 12 CONF_ENCHx x: 0~11 ADDR2/CLK 1 0h: 200Hz 1h: 250Hz 2h: 300Hz 3h: 350Hz 4h: 400Hz 5h: 500Hz 6h: 600Hz 7h: 800Hz 8h: 1000Hz 9h: 1200Hz Ah: 2000Hz Bh: 4000Hz Ch: 5900Hz Dh: 7800Hz Eh: 9600Hz Fh: 20800Hz CONF_PWMFREQ[3:0] MUX Internal Oscillator 0 Figure 8-2. PWM Generator Path Diagram 8.3.3.3 Linear Brightness Control When register CONF_EXPEN is set to 0, the MSB 8 bits of 12-bit binary input to PWM generator is directly copied from 8-bit register CONF_PWMOUTx, and the LSB 4 bits is directly copied from 4-bit register CONF_PWMLOWOUTx. The PWM output duty cycle can be calculated with Equation 3. Because the 4 LSB bits inputs are used to control the dithering, setting CONF_PWMLOWOUTx to Fh disables the dithering if it is not needed. The PWM output duty cycle is linearly controlled by the register CONF_PWMOUTx and CONFPWMLOWOUTx, which provides the linearly brightness control to each channel output. D(OUTx) (16 u CONF_PWMOUTx+CONF_PWMLOWOUTx+1) u 100% 4096 (3) where • • • CONF_PWWOUTx is decimal number from 0 to 255. CONF_PWMLOWOUTx is decimal number from 0 to 15. x is from 0 to 11 for different output channel. If using the dithering feature to realize the 12-bit dimming resolution, set the PWM frequency higher than 2 kHz through setting register CONF_PWMFREQ to avoid visible brightness flicker when the value of CONF_PWMLOWOUTx is less than Fh. Higher PWM frequency can also prevent the visible LED flash in video display due to the low beat frequency between digital camera shutter frequency and PWM frequency for LED dimming. Because the 12-bit PWM duty cycles require 2 bytes of write operation to update the completed data, the output PWM duty cycle is not changed in between of the two bytes data transmission. TPS929121-Q1 only updates PWM duty cycle of any output when its high 8-bit CONF_PWMOUTx is written. When very fast brightness change is needed, for example, fade-in and fade-out effects, simultaneous PWM duty cycle change of all 18 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 channels is required. Setting CONF_SHAREPWM to 1 enables all channels using the PWM dutycycle setting of channel 0 to save communication latency. 8.3.3.4 Exponential Brightness Control The TPS929121-Q1 can also generate PWM duty-cycle output following exponential curve. The integrated lookup table provides a one-to-one conversion from 8-bit register CONF_PWMOUTx to 12-bit binary code following exponential increment when register CONF_EXPEN is set to 1 as Figure 8-3 illustrated. When exponential control path is selected, the CONF_PWMLOWOUTx data is neglected. By using the exponential brightness control, LED brightness change by one LSB is invisible to human eyes especially at low brightness range. 4096 12-Bit Lookup Table Output 3584 3072 2560 2048 1536 1024 512 0 0 32 64 96 128 160 8-Bit CONF_PWMOUTx[7:0] 192 224 256 D100 Figure 8-3. PWM Duty Cycle vs 8-bit Code for Exponential Dimming CONF_EXPEN bit selects the dimming method between linear or exponential. Setting the bit CONF_EXPEN to 1 enables the look-up table for exponential dimming curve. In exponential PWM dimming mode, 8-bit register CONF_PWMOUTx is converted to 12-bit PWM dutycycle by look-up table automatically. Clear the bit CONF_EXPEN to 0 disables the look-up table. In this case, users must provide 12-bit PWM duty cycle. CONF_PWMOUTx stores the high 8-bit of 12-bit PWM duty-cycle information. CONF_PWMLOWOUTx stores the low 4-bit. To avoid visible brightness flicker for exponential dimming, choose PWM frequency higher than 2 kHz through setting register CONF_PWMFREQ. Higher PWM frequency can also avoid the visible LED flash in video display due to the low beat frequency between digital camera shutter frequency and PWM frequency for LED dimming. During power-up or in fail-safe state, the registers CONF_EXPEN, CONF_PWMOUTx, CONF_PWMFREQ are automatically reset to their default values stored in EEPROM register EEP_EXPEN, EEP_PWMOUTx, EEP_PWMFREQ. CONF_PWMLOWOUTx is reset to Fh as default value. In fail-safe state, PWM generator only uses 8-bit EEPROM data from EEP_PWMOUTx to build PWM dutycycle output and ignores the low 4-bit. The PWM duty-cycle calculation is as shown in Equation 4. D(OUTx) (EEP_PWMOUTx+1) u 100% 256 (4) where • • EEP_PWMOUTx is decimal number from 0 to 255. x is from 0 to 11 for different output channel. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 19 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 8.3.3.5 External Clock Input for PWM Generator (CLK) The TPS929121-Q1 has internal precision oscillator for PWM generators. In addition, the device also supports an external clock for the PWM generator source with ADDR2/CLK input considering the synchronization requirement. Then external clock inputs through ADDR2/CLK pin is a multi-function pin not only for external clock input but also for device slave address selection. The device slave address stored in EEPROM must be enabled by burning EEP_INTADDR to 1 to release ADDR2/CLK pin for external clock input. In addition, register CONF_EXTCLK can be used to choose the PWM generator between external input or an internal oscillator. Writing CONF_EXTCLK to 1 enables the external clock source. The external clock frequency must be 256 times of desired PWM dimming frequency. The external clock source is only used in PWM generation. TI recommends that the external clock frequency be less than 1 MHz. The internal clock is recommended when high dimming frequency is required. 8.3.3.6 External PWM Input ( PWM0 and PWM1) The TPS929121-Q1 has two PWM inputs that can be used to directly control OUT0-11. The both ADDR1/ PWM1 and ADDR0/ PWM0 pins are multi-function pins for not only external PWM input signal but also device slave address selection pins. The register EEP_INTADDR must be written to 1 to release both twos for external PWM input. When the EEP_INTADDR is 1, the ADDR0/ PWM0 is functional as external active low PWM control input for OUT0-5 and the ADDR1/ PWM1 is functional as external active low PWM control input for OUT6-11, as shown in Figure 8-2. Setting the register CONF_PWMOUTx to 0xFF and the register CONF_PWMLOWOUTx to 0xF is recommended when external PWM input is used. In case external PWM is not used, ADDR0/ PWM0 and ADDR1/ PWM1 must be tied to GND when EEP_INTADDR is set to 1. 8.3.4 On-chip 8-bit Analog-to-Digital Converter (ADC) The TPS929121-Q1 has integrated a successive-approximation-register (SAR) ADC for diagnostics. It routinely monitors supply voltage if the ADC is idle and stores SUPPLY conversion results into ADC_SUPPLY. To manually read the voltage of an ADC channel as listed in Table 8-2, user must write the 5-bit register CONF_ADCCH to select channel. Once CONF_ADCCH register is written, the one time ADC conversion starts and clears FLAG_ADCDONE register. As long as the ADC conversion is completed, the ADC result is available in 8-bit register ADC_OUT and sets FLAG_ADCDONE to 1. Reading the ADC_OUT register also clears FLAG_ADCDONE, and the FLAG_ADCDONE is set to 0 after reading completion. Because the TPS929121-Q1 supports PWM control for adjusting LED brightness, the voltage on OUT0 to OUT11 is like a pulse waveform. When the current output is enabled by setting CONF_ENCHx to 1, the ADC measures the voltage on assigned OUTx after the channel is turned on with t(diag_pulse) delay time, which is programmable by 4-bit register CONF_ODPW. When the channel is disabled by setting CONF_ENCHx to 0, the ADC samples the voltage on assigned OUTx at off state. The analog value can be calculated based on the read back binary code with Equation 5 and Table 8-2. AnalogValue a k u ADC _ OUT (5) where • 20 ADC_OUT is decimal number from 0 to 255. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 Table 8-2. ADC Channel CHANNEL NO. CONF_ADCCH NAME ADC ADC CALCULATION CALCULATION PARAMETER PARAMETER (a) (k) COMMENT 0 00h REF 0.007 V 0.0101 V/LSB Reference voltage 1 01h SUPPLY 0.2878 V 0.1583 V/LSB Supply voltage 2 02h VLDO 0.0465 V 0.022 V/LSB 5-V LDO output voltage 3 03h TEMPSNS –304.7 °C 2.463°C/LSB Internal temperature sensor 4 04h IREF 0.7592 µA 0.7461 µA/LSB Reference current 5 05h MAXOUT 0.2878 V 0.1583 V/LSB Maximum channel output voltage 6-15 06h - 0Fh RESERVED RESERVED RESERVED RESERVED 16 10h OUT0 Output voltage channel 0 17 11h OUT1 Output voltage channel 1 18 12h OUT2 Output voltage channel 2 19 13h OUT3 Output voltage channel 3 20 14h OUT4 Output voltage channel 4 21 15h OUT5 22 16h OUT6 23 17h OUT7 Output voltage channel 7 24 18h OUT8 Output voltage channel 8 25 19h OUT9 Output voltage channel 9 26 1Ah OUT10 Output voltage channel 10 27 1Bh OUT11 Output voltage channel 11 28 1Ch RESERVED RESERVED RESERVED RESERVED 29 1Dh RESERVED RESERVED RESERVED RESERVED 30 1Eh RESERVED RESERVED RESERVED RESERVED 31 1Fh RESERVED RESERVED RESERVED RESERVED 0.2878 V 0.1583 V/LSB Output voltage channel 5 Output voltage channel 6 The TPS929121-Q1 also provides ADC auto-scan mode for single-led short-circuit diagnostics. The detail description for auto-scan mode can be found in On-Demand Off-State Single-LED Short-Circuit (SS) Diagnostics. In ADC auto-scan mode, If MAXOUT channel is selected by writing 05h to CONF_ADCCH, the maximum voltage of OUT0 to OUT11 is recorded into ADC_OUT register. The maximum channel output voltage is available after at least one output PWM cycle is completed. Based on the measured maximum output voltage and supply voltage, microcontroller is able to regulate supply voltage from previous power stage to minimize the power consumption on the TPS929121-Q1. Basically microcontroller needs to program the output voltage of previous power stage to be just higher than the measured maximum channel output voltage plus the required dropout voltage V(OUT_drop) of the TPS929121-Q1. In this way, the TPS929121-Q1 takes minimum power consumption, and overall power efficiency is optimized. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 21 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 8.3.5 Diagnostic and Protection in Normal State The TPS929121-Q1 has full-diagnostics coverage for supply voltage, current output, and junction temperature. In normal state, the device detects all failures and reports the status out through the ERR or FLAG registers, without any actions taken by the device except UVLO and overtemperature protection. The master controller must handle all fault actions, for example, retry several times and shut down the outputs if the error still exists. The fault behavior in normal state can be found in Table 8-3. 8.3.5.1 Fault Masking The TPS929121-Q1 provides fault masking capability using masking registers. The device is capable of masking faults by channels or by fault types. The fault masking does not disable diagnostics features but only prevents fault reporting to FLAG_OUT register, FLAG_ERR register, and ERR output. To disable diagnostics on a single channel, setting CONF_DIAGENCHx registers to 0 disables diagnostics of channel x and thus no fault of this channel is reported to FLAG_OUT or FLAG_ERR registers, or to the ERR output. CONF_MASKREF prevents the reference fault being reported to FLAG_ERR and ERR output. CONF_MASKOPEN prevents the output open-circuit fault being reported to FLAG_OUT, FLAG_ERR and ERR output. CONF_MASKSHORT prevents the output short-circuit fault being reported to FLAG_OUT, FLAG_ERR and ERR output. CONF_MASKTSD prevents the overtemperature shutdown fault being reported to FLAG_ERR and ERR output. CONF_MASKCRC prevents the CRC fault being reported to FLAG_ERR and ERR output. 8.3.5.2 Supply Undervoltage Lockout Diagnostics in Normal State When SUPPLY or VLDO voltage drops below its UVLO threshold, the device enters POR state. Upon voltage recovery, the device automatically switches to INIT state with FLAG_POR and FLAG_ERR set to 1. 8.3.5.3 Low-Supply Warning Diagnostics in Normal State The internal AD converter of TPS92910-Q1 continuously monitors the supply voltage and compares the results with internal threshold V(ADCLOWSUPTH) set by CONF_ADCLOWSUPTH as described in Register Maps. If the supply voltage is lower than threshold, the device pulls ERR pin down with one pulsed current sink for 50 µs to report the fault and set flag registers including FLAG_ADCLOWSUP to 1. The master controller can write register CLR_FAULT to 1 to reset this flag, and the CLR_FAULT bit automatically returns to 0. The internal ADC monitors supply voltage and converters to 8-bit binary code in every conversion cycle T(CONV) when it is in idle. After each AD conversion-cycle time on supply, the ADC_SUPPLY is automatically updated with the latest result. The low-supply warning is also used to disable the LED open-circuit detection and single-LED short-circuit detection. When the voltage applied on SUPPLY pin is higher than the threshold V(ADCLOWSUPTH), the TPS929121-Q1 enables LED open-circuit and single-LED short-circuit diagnosis. When V(SUPPLY) is lower than the threshold V(ADCLOWSUPTH), the device disables LED-open-circuit detection and single-LED short-circuit diagnosis. Because when V(SUPPLY) drops below the maximum total LED forward voltage plus required V(DROPOUT) at required current, the TPS929121-Q1 is not able to deliver sufficient current output to pull the voltage of each output channel as close as possible to the V(SUPPLY). In this condition, the LED open-circuit fault or single-LED short-circuit fault might be detected and reported by mistake. Setting the low-supply warning threshold high enough can avoid the LED open-circuit and single LED short-circuit fault being detected when V(SUPPLY) drops to low. The V(ADCLOWSUPTH) is programmable from 5 V to 20 V. 8.3.5.4 Reference Diagnostics in Normal State The TPS929121-Q1 integrates diagnostics for REF resistor open/short fault. If the current output from REF pin I(REF) is lower than I(REF_OPEN_th), the reference resistor open-circuit fault is reported. The reference resistor short-circuit fault is reported if the voltage of REF pin V(REF) is lower than V(REF_SHORT_th). The device pulls the 22 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 ERR pin down with constant current sink and set flag registers including FLAG_REF and FLAG_ERR to 1. The master controller must send CLR_FAULT to clear fault flag registers after fault removal. In normal state, the device does not perform any actions automatically when reference resistor fault is detected. However, the output may not work properly and the output current may be operating at high current level. It is recommended for master controller to shut down the device outputs and report error to upper level control system such as body control module (BCM). The TPS929121-Q1 monitors the reference current I(REF) set by external resistor R(REF). The I(REF) can be calculated with Equation 6. I(REF) V(REF) R(REF) (6) where • V(REF) = 1.235 V typically 8.3.5.5 Pre-Thermal Warning and Overtemperature Protection in Normal State The TPS929121-Q1 has pre-thermal warning at typical 135°C and overtemperature shutdown at typical 175°C. When the junction temperature T(J) of TPS929121-Q1 rises above pre-thermal warning threshold, the device reports pre-thermal warning, pull ERR pin with pulsed current sink for 50 µs and sets the flag registers including FLAG_PRETSD to 1. The master controller must write 1 to CLR_FAULT register to clear FLAG_PRETSD. When device junction temperature T(J) further rises above overtemperature protection threshold, the device shuts down all output drivers, pulls the ERR pin low with constant current sink, and sets the flag registers including FLAG_TSD and FLAG_ERR to 1. When junction temperature falls below T(TSD) – T(TSD_HYS), the device resumes all outputs and releases ERR pin pulldown. The FLAG_TSD still must be cleared by writing CLR_FAULT to 1. If the T(J) rises too high above 180oC typically, the TPS929121-Q1 turns off the internal linear regulator to shutdown all the analog and digital circuit. When the T(J) drops below T(TSD) - T(TSD_HYS), the TPS929121-Q1 restarts from POR state with all the registers cleared to default value. When more accurate thermal measurement on LED unit is required, one current output channel can be sacrificed to provide current bias to external thermal resistor such as PTC or NTC. The voltage of external thermal resistor can be measured by integrated ADC to acquire the temperature information of thermal resistor located area. The master controller can determine actions based on the acquired temperature information to turn off or reduce current output. 8.3.5.6 Communication Loss Diagnostic in Normal State The TPS929121-Q1 monitors the FlexWire interface for the communication with an internal watchdog timer. Any successful non-broadcast communication with correct CRC and address matching target device automatically resets the timer . If the watchdog timer overflows, device automatically switches to fail-safe state as indicated by external FS input. If FS = 0, the device switches to fail-safe state 0, If FS = 1, the device switches to fail-safe state 1. The watchdog timer is programmable by 4-bit register CONF_WDTIMER. The TPS929121-Q1 can directly enter fail-safe states from normal mode by burning EEP_WDTIMER to 0xFh. Disabling the watchdog timer by setting CONF_WDTIMER to 0x0h prevents the device from getting into fail-safe state. 8.3.5.7 LED Open-Circuit Diagnostics in Normal State The TPS929121-Q1 integrates LED open-circuit diagnostics to allow users to monitor LED status real time. The device monitors voltage difference between SUPPLY and OUTx to judge if there is any open-circuit failure. The SUPPLY voltage is also monitored by on-chip ADC with programmable threshold to determine if supply voltage is high enough for open-circuit diagnostics. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 23 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 The open-circuit monitor is only enabled during PWM-ON state with programmable minimal pulse width greater than T(ODPW) + T(OPEN_deg). The T(ODPW) is programmed by register CONF_ODPW. If PWM on-time is less than T(ODPW) + T(OPEN_deg), the device does not report any open-circuit fault. When the voltage difference V(SUPPLY) – V(OUTx) is below threshold V(OPEN_th_rising) with duration longer than T(ODPW) + T(OPEN_deg), and the device supply voltage V(SUPPLY) is above the threshold V(ADCLOWSUPTH) set by register CONF_ADCLOWSUPTH, the TPS929121-Q1 pulls the ERR pin down with one pulsed current sink for 50 µs to report fault and set flag registers including FLAG_OPENCHx, FLAG_OUT and FLAG_ERR to 1. If the device supply voltage V(SUPPLY) is below the threshold V(ADCLOWSUPTH) set by register CONF_ADCLOWSUPTH, open-circuit fault is not detected nor reported. Once the open-circuit failure is removed, the master controller must write 1 to CLR_FAULT to reset fault flags. 8.3.5.8 LED Short-Circuit Diagnostics in Normal State The TPS929121-Q1 has internal analog comparators to monitor all channel outputs with respect to a fixed threshold. If the device has detected channel voltage below threshold, it sets FLAG_SHORTCHx accordingly. The FLAG_OUT and FLAG_ERR are set as well. Writing 1 to CLR_FAULT register is able to clear the fault flag registers. The short-circuit detection is only enabled during PWM-ON state with programmable minimal pulse width of T(ODPW) + T(SHORT_deg). The T(ODPW) is programmable by register CONF_ODPW. If PWM on-time is less than T(ODPW) + T(SHORT_deg), the device can not report any short-circuit fault. When the voltage V(OUTx) is below threshold V(SG_th_rising) with duration longer than deglitch timer length of T(ODPW) + T(SHORT_deg), the device pulls ERR pin down with pulsed current sink for 50 µs to report fault and set flag registers including FLAG_SHORTCHx, FLAG_OUT and FLAG_ERR. In normal state, the device does not take any actions in response the LED short-circuit fault and waits for the master controller to detect need for protection behavior. The fault is latched in flag registers. The master controller must write 1 to register CLR_FAULT to reset fault flags if the LED short-circuit fault is removed. Possible user case: 1. 2. 3. 4. 5. Supply voltage dip below threshold, triggering false single led short-circuit fault LED short to ground and recover LED single LED short and recover Dutycycle too short to detect Extra capacitance caused false short-circuit 8.3.5.9 On-Demand Off-State Invisible Diagnostics It is commonly required to ensure there is no fault on each LED load before lighting them up, especially for LED animation. Otherwise, the LED fault is detected in the middle of the admiration pattern, which results a random and uncertain failure animation pattern. The TPS929121-Q1 provides a solution to diagnose the LED opencircuit or LED short-circuit fault without lighting up the LEDs. With this feature, the master controller can initiate the on-demand invisible diagnostics before commencing the animation sequence. If one of the channel fails, the device is able to detect it immediately instead of only when the fault channel is turned on in traditional diagnostics mode. To initiate the on-demand invisible diagnostics, the master controller writes register CONF_INVDIAGSTART to 1. The register CONF_INVDIAGSTART returns to 0 automatically in the next clock cycle. Once the diagnostics started, the on-demand diagnostics ready flag FLAG_ODREADY is cleared to 0. Once the diagnostics finished, the FLAG_ODREADY is set to 1. If any channel has output failures, its ondemand diagnostic flag FLAG_ODDIAGCHx is set 1. To ensure the invisibility of the diagnostics, the TPS929121-Q1 outputs only a small DC current in short period to each output channel and detects if there is any LED open-circuit or LED short-circuit failures. The output DC current I(ODIOUT) can be adjusted to a proper value by setting the DC current CONF_ODIOUT and ignoring the DC current setup by register CONF_IOUTx. The pulse-width T(ODPW) of output DC current can be programmable by CONF_ODPW and neglecting duty cycle configuration by register CONF_PWMOUTx. At the end of the current output pulse, if there is any LED open-circuit fault as LED Open-Circuit Diagnostics in Normal State described, the TPS929121-Q1 pulls the ERR pin down with one pulsed current sink for 50 µs to report fault and set flag registers including FLAG_OPENCHx, FLAG_OUT and FLAG_ERR to 1. If there is any LED short-circuit 24 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 fault as LED Short-Circuit Diagnostics in Normal State described, the TPS929121-Q1 pulls the ERR pin down with one pulsed current sink for 50 µs to report fault and set flag registers including FLAG_SHORTCHx, FLAG_OUT and FLAG_ERR to 1. The master controller must write 1 to CLR_FAULT register to clear fault flags after the fault removal is verified by another on-demand off-state invisible diagnostics. TI recommends turning off all output channels by set CONF_ENCHx to 0 before invisible diagnostics. For invisible diagnostics mode, it is required to have a short-pulse and low output current to avoid lighting up LEDs. However, the diagnostics are strongly affected by large loading capacitance. If the invisible diagnostics pulse failed to charge output capacitance above short-circuit threshold, the device reports a false short-circuit failure. If pulse failed to charge output above open-circuit threshold at maximum supply voltage, the device does not report open-circuit fault correctly. Thus, the DC current and period of the detection pulse must be carefully selected based on the capacitance value at output in real application. Invisible Diagnostics OUT0 tT(ODPW)t Programmable pulse width Programmable diagnostic current Normal OUT1 Short-circuit detected Short-circuit OUT11 Open-circuit Open-circuit detected Figure 8-4. Programmable Invisible Diagnostics Timing Sequence 8.3.5.10 On-Demand Off-State Single-LED Short-Circuit (SS) Diagnostics To provide single-LED short-circuit diagnostics, the TPS929121-Q1 uses internal ADC to compare the output channel voltage with respect to pre-set threshold V(ADCSHORTTH). Setting the register CONF_SSSTART to 1 starts the diagnostics immediately. The CONF_SSSTART returns to 0 in the next clock cycle. Once the diagnostics starts, the on-demand diagnostics ready flag FLAG_ODREADY are cleared to 0. Once the diagnostics finished, the FLAG_ODREADY are set to 1. In off-state single-LED short-circuit diagnostics, once the master controller initiates single-LED short-circuit diagnostics by setting the register CONF_SSSTART, the device sequentially turns on all outputs starting from OUT0 with DC current I(ODIOUT) programed by register CONF_ODIOUT and pulse width T(ODPW) programmable by CONF_ODPW. At the end of pulse, the device initiates an AD conversion. As long as the completion of ADC conversion, the result are compared with pre-set threshold V(ADCSHORTTH) and start the diagnostics for the next channel. After all channels have been checked, the TPS929121-Q1 also checks if the supply voltage is over V(ADCLOWSUPTH) to make sure the device is not in low-dropout conditions. If the supply voltage is truly lower than V(ADCLOWSUPTH), the single-LED short-circuit fault cannot be detected and reported. If the supply voltage is high enough, and any one channel output voltage is less than pre-set threshold V(ADCSHORTTH), the TPS92910-Q1 pulls the ERR pin down with pulsed current sink for 50 µs to report fault and set the flag register including FLAG_ODDIAGCHx, FLAG_OUT and FLAG_ERR to 1. The master controller must write 1 to CLR_FAULT register to clear the fault flags after fault removal is verified by another on-demand off-state single-LED shortcircuit diagnostic. The configurable DC current I(ODIOUT) and pulse width T(ODPW) can be used to minimize the optical impact during on-demand diagnostics. TI recommends using the normal current setting and short pulse-width to avoid visible pulse; however, the parasitic capacitance impact at each output must taken care of to leave enough charging time and avoid false alarm. Low DC current setting also reduces LED forward voltage, which also affects the integrity of the detection. Thus the threshold set by CONF_ADCSHORTTH must be selected carefully. Setting CONF_ODIOUT to 0xFh uses the channel current setting by register CONF_IOUTx as on-demand pulse current. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 25 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 The V(ADCSHORTTH) can be calculated with Equation 7. V(ADCSHORTTH) a k u CONF _ ADCSHORTTH (7) where • • • a = 0.2878 V. k = 0.1583 V/LSB. CONF_ADCSHORTTH is decimal number from 0 to 255. Single-LED Shortcircuit diagnostic ADC IDLE OUT0 Conversion IDLE OUT1 Conversion OUT11 Conversion SUPPLY Conversion IDLE Single-LED short-circuit detected OUT0 T(ODPW) OUT1 Single-LED Short-circuit OUT11 Figure 8-5. Single-LED Short-Circuit Off-state Timing Sequence 8.3.5.11 Automatic Single-LED Short-Circuit (AutoSS) Detection in Normal State In order to check LED single-LED short-circuit issue during lighting up, the TPS929121-Q1 also provides automatically single-LED short-circuit (AutoSS) diagnostic. Setting the register CONF_AUTOSS to 1 enables the scanning of each current out channel at the beginning of every PWM cycle. The AutoSS detection takes two PWM cycles to complete scanning. The channel OUT0 to OUT5 are scanned in first cycle and the OUT6 to OUT11 are scanned in second cycle as depicted in Figure 8-6. On PWM rising edge, the device waits for a programmable delay T(ODPW) programmable by CONF_ODPW to allow output voltage settle and start AD conversion. The minimal pulse width of PWM must be longer than programmable delay T(ODPW) plus 6 times AD conversion time T(CONV) to make sure 6 output channels can be scanned in one PWM cycle. The TPS929121-Q1 checks low-supply warning to avoid reporting the single-LED short-circuit fault by mistake in low-dropout mode. If the supply voltage is truly lower than V(ADCLOWSUPTH), the single-LED short-circuit fault cannot be detected and reported. If the supply voltage is high enough, and any one channel output voltage is less than pre-set threshold V(ADCSHORTTH), the TPS92910-Q1 pulls ERR pin down with pulsed current sink for 50 µs to report fault and set the flag register including FLAG_ODDIAGCHx, FLAG_OUT and FLAG_ERR to 1. The master controller must write 1 to CLR_FAULT register to clear the fault flags. The single-LED short circuit threshold V(ADCSHORTTH) is programmable by CONF_ADCSHORTTH. If any channel is disabled by CONF_ENCHx to 0, the AutoSS diagnostics skips the channel. During the single-led short-circuit diagnostics, the ADC keeps the on-demand ADC conversion request pending until single-led short-circuit diagnostics finished. TI does not recommend using external PWM inputs when AutoSS is required to avoid false diagnostics. When CONF_AUTOSS is set to 1, selecting MAXOUT by writing 05h to CONF_ADCCH automatically outputs the ADC conversion result to register ADC_OUT for the output channel with the highest voltage in all scanned channels. The master controller can adjust the previous power stage output voltage based on the voltage difference read back from register ADC_SUPPLY and ADC_OUT to minimize the voltage drop on the 26 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 TPS929121-Q1 as well as temperature rising if the output voltage of previous power stage is programmable by digital interface. Single-LED Shortcircuit diagnostic Wait for next PWM rising edge Programmable Delay AD Conversion Next PWM Rising Edge Programmable Delay T(ODPW) ADC IDLE AD Conversion T(ODPW) OUT0 OUT1 OUT4 OUT5 SUPPLY IDLE OUT6 OUT7 OUT10 OUT11 SUPPLY IDLE OUT0 OUT1 Single-LED Short-circuit OUT11 Figure 8-6. Single-LED Short-Circuit On-state Diagnostics Timing Sequence 8.3.5.12 EEPROM CRC Error in Normal State The TPS929121-Q1 implements a EEPROM CRC check after loading the EEPROM code to configuration register in normal state. The calculated CRC result is sent to register CALC_EEPCRC and compared to the data in EEPROM register EEP_CRC, which stores the CRC code for all EEPROM registers. If the code in register CALC_EEPCRC is not matched to the code in register EEP_CRC, the TPS929121-Q1 pulls the ERR pin down with pulsed current sink for 50 µs to report the fault and set the registers including FLAG_EEPCRC and FLAG_ERR to 1. The master controller must write CLR_FAULT to 1 to clear the fault flags. The CRC code for all the EEPROM registers must be burnt into EEPROM register EEP_CRC in the end of production line. The CRC code algorithm for multiple bytes of binary data is based on the polynomial, X8 + X5 + X4 + 1. The CRC code contain 8 bits binary code, and the initial value is FFh. As described in Figure 8-7, all bits code shift to MSB direction for 1 bit with three exclusive-OR calculation. A new CRC code for one byte input could be generated after repeating the 1-bit shift and three exclusive-OR calculation for 8 times. Based on this logic, the CRC code can be calculated for all the EEPROM register byte. When the EEPROM design for production is finalized, the corresponding CRC code based on the calculation must be burnt to EEPROM register EEP_CRC together with other EEPROM registers in the end of production line. If the DC current for each output channel needs to be calibrated in the end of production for different LED brightness bin, the CRC code for each production devices must be calculated independent and burnt during the calibration. The CRC algorithm must be implemented into the LED calibration system in the end of production line. XOR CRC Bit 7 CRC Bit 6 CRC Bit 5 XOR CRC Bit 4 XOR CRC Bit 3 CRC Bit 2 CRC Bit 1 CRC Bit 0 Bit Input LSB First Figure 8-7. CRC Algorithm Diagram Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 27 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 Table 8-3. Diagnostics Table in Normal State FAULT TYPE Supply UVLO Low-supply warning Reference fault Pre-thermal warning Overtemperature protection Communication loss fault DETECTION CRITERIA CONDITIONS FAULT ACTIONS V(SUPPLY) < V(POR_falling) or V(LDO) < V(LDO_POR_falling) Device switch to POR state V(SUPPLY) < V(ADCLOWSUPTH) Disable fault type * V(REF) < V(REF_SHORT_th) or I(REF) < I(REF_OPEN_th) T(J) > T(PRETSD) T(J) > T(TSD) T(WDTIMER) overflows FAULT OUTPUT ERR PIN RECOVERY FLAG_POR FLAG_ERR Constant pulled down Device switch to INIT state when all voltage rails are good. Clear fault flag with CLR_POR FLAG_ADCLOWSUP FLAG_ERR One pulse pulled down for 50µs Clear fault flag with CLR_FAULT No action FLAG_REF FLAG_ERR (Maskable) Constant pulled down (maskable) Clear fault flag with CLR_FAULT No action FLAG_PRETSD One pulse pulled down for 50µs Clear fault flag with CLR_FAULT FLAG_TSD Turn off all channels FLAG_ERR (Maskable) Constant pulled down (maskable) Automatically recover upon junction temperature falling below threshold with hysteresis. Clear fault flag with CLR_FAULT Enter fail-safe states FLAG_FS No action Set CLR_FS to 1 to set the device to normal state LED open-circuit fault * V(SUPPLY) - V(OUTx) < V(OPEN_th_rising) and V(SUPPLY) > V(ADCLOWSUPTH) PWM pulse width greater than T(ODPW) + T(OPEN_deg) CONF_ENCHx = 1 CONF_DIAGENCHx = 1 No action FLAG_OPENCHx FLAG_OUT (Maskable) FLAG_ERR (Maskable) One pulse pulled down for 50 µs (maskable) Clear fault flag with CLR_FAULT LED short-circuit fault V(OUTx) < V(SG_th_rising) PWM pulse width greater than T(ODPW) + T(SHORT_deg) CONF_ENCHx = 1 CONF_DIAGENCHx = 1 No action FLAG_SHORTCHx FLAG_OUT (Maskable) FLAG_ERR (Maskable) One pulse pulled down for 50 µs (maskable) Clear fault flag with CLR_FAULT On-demand off-state invisible diagnostic LED Open-circuit or LED Short-circuit fault Pulse Width: T(ODPW) Current: I(ODIOUT) CONF_ENCHx = 0 CONF_DIAGENCHx = 1 CONF_INVDIAGSTART = 1 No action FLAG_ODREADY FLAG_ODDIAGCHx FLAG_OUT FLAG_ERR One pulse pulled down for 50 µs Clear fault flag with CLR_FAULT On-demand off-state single-LED Shortcircuit * V(OUTx) < V(ADCSHORTTH) and V(SUPPLY) > V(ADCLOWSUPTH) Pulse Width: T(ODPW) Current: I(ODIOUT) CONF_ENCHx = 0 CONF_DIAGENCHx = 1 CONF_SSSTART = 1 No action FLAG_ODREADY FLAG_ODDIAGCHx FLAG_OUT FLAG_ERR One pulse pulled down for 50 µs Clear fault flag with CLR_FAULT Auto single-LED short circuit * V(OUTx) < V(ADCSHORTTH) and V(SUPPLY) > V(ADCLOWSUPTH) PWM pulse width greater than T(ODPW)+ 6*T(CONV) CONF_ENCHx = 1 CONF_DIAGENCHx = 1 CONF_AUTOSS = 1 No action FLAG_ODDIAGCHx FLAG_OUT FLAG_ERR One pulse pulled down for 50 µs Clear fault flag with CLR_FAULT No action FLAG_EEPCRC FLAG_ERR (Maskable) One pulse pulled down for 50 µs (maskable) Clear fault flag with CLR_FAULT EEPROM CRC error 28 CALC_EEPCRC is different EEP_CRC Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 8.3.6 Diagnostic and Protection in Fail-Safe States In fail-safe state, the TPS929121-Q1 also detects all failures and reports the status out by ERR or FLAG registers. The summary of the fault detection criteria and the device behavior after fault detected is listed in Table 8-4. Basically the TPS929121-Q1 actively takes the action to turn off the failed output channels, retry on the failed channels, or restart the device to keep device operating without controlled by master. The EEPROM register EEP_OFAF can be used to set the fault behavior for LED short-circuit and LED open-circuit. The onefails-all-fail behavior is selected when the register EEP_OFAF is burnt to 1; otherwise the one-fails-others-on behavior is chosen. The TPS929121-Q1 turns off all output channels when any one type of LED fault is detected on any one of output channels for one-fails-all-fail behavior. On the other hand, the TPS929121-Q1 only turns off the failed channel and keep all other normal channels on. In fail-safe state, the fault flag registers of TPS929121-Q1 still can be accessed through FlexWire interface for master controller to identify the fault. 8.3.6.1 Fault Masking The TPS929121-Q1 provides fault masking capability by masking registers. The device is capable of masking faults by channels or by fault types. The fault masking doe not disable diagnostics features but only prevents fault reporting to FLAG_OUT register, FLAG_ERR register, and ERR output. To disable diagnostics on a single channel, setting CONF_DIAGENCHx registers to 0 disables diagnostics of channel x and thus no fault of this channel is reported to FLAG_OUT, FLAG_ERR registers, and ERR output. CONF_MASKREF prevents the reference fault being reported to FLAG_ERR and ERR output. CONF_MASKOPEN prevents the output open-circuit fault being reported to FLAG_OUT, FLAG_ERR and ERR output. CONF_MASKSHORT prevents the output short-circuit fault being reported to FLAG_OUT, FLAG_ERR and ERR output. CONF_MASKTSD prevents the overtemperature shutdown fault being reported to FLAG_ERR and ERR output. CONF_MASKCRC prevents the CRC fault being reported to FLAG_ERR and ERR output. 8.3.6.2 Supply UVLO Diagnostics in Fail-Safe States When SUPPLY or VLDO voltage drops below its UVLO threshold, the device enter into POR state. Upon voltage recovery, the device automatically switches to INIT state with FLAG_POR and FLAG_ERR set to 1. 8.3.6.3 Low-supply Warning Diagnostics in Fail-Safe states The internal ADC of TPS92910-Q1 continuously monitors supply voltage and compares the results with internal threshold V(ADCLOWSUPTH) set by CONF_ADCLOWSUPTH as described in Register Maps. If the supply voltage is lower than threshold, the device sets flag registers including FLAG_ADCLOWSUP and FLAG_ERR to 1. Master controller can write register CLR_FAULT to 1 to reset this flag, and the CLR_FAULT bit automatically returns to 0. The internal ADC monitors supply voltage and converters to 8-bit binary code in every conversion cycle T(CONV) when it is in idle. After each AD conversion cycle time on supply, the ADC_SUPPLY is automatically updated with the latest result. 8.3.6.4 Reference Diagnostics at Fail-Safe States The TPS929121-Q1 integrates diagnostics for REF resistor open/short fault. If the current output from REF pin I(REF) is lower than I(REF_OPEN_th), the reference resistor open-circuit fault is reported. Or the reference resistor short-circuit fault is reported if the voltage of REF pin V(REF) is lower than V(REF_SHORT_th). The device pulls ERR pin down with constant current sink and set flag registers including FLAG_REF and FLAG_ERR to 1. In fail-safe state, the device turns off all output channels if reference fault is detected. The device automatically recovers and turns on all used channel after fault removal. The master controller need send CLR_FAULT to clear the flag register after fault removal. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 29 TPS929121-Q1 SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 www.ti.com The TPS929121-Q1 monitors the reference current I(REF) set by external resistor R(REF). The I(REF) can be calculated with Equation 6. 8.3.6.5 Overtemperature Protection in Fail-Safe State When the junction temperature T(J) of TPS929121-Q1 rises above overtemperature protection threshold, the device shuts down all output drivers, pulls ERR pin low with constant current sink, and sets flag register including FLAG_TSD and FLAG_ERR to 1. When junction temperature falls below T(TSD) - T(TSD_HYS), the device resumes all outputs and releases ERR pin pulldown. The FLAG_TSD still can be cleared by writing CLR_FAULT to 1. If the T(J) rises too high above 180oC typically, the TPS929121-Q1 turns off the internal linear regulator to shutdown all the analog and digital circuit. When the T(J) drops below T(TSD) - T(TSD_HYS), the TPS929121-Q1 restarts from POR state with all the registers cleared to default value. 8.3.6.6 LED Open-circuit Diagnostics in Fail-Safe State The TPS929121-Q1 integrates LED open-circuit diagnostics to allow users to monitor LED status in real time. The device monitors voltage difference between SUPPLY and OUTx to detect if there is any open-circuit failure. The SUPPLY voltage is also monitored by on-chip ADC with programmable threshold to detect if supply voltage is high enough for open-circuit diagnostics. The open-circuit monitor is only enabled during PWM-ON state with minimal pulse width greater than T(ODPW) + T(OPEN_deg). If PWM on-time is less than T(ODPW) + T (OPEN_deg), the device does not report any open-circuit fault. T(ODPW) is programmable by register CONF_ODPW. When the voltage difference V(SUPPLY) – V(OUTx) is below threshold V(OPEN_th_rising) with duration longer than T(ODPW) + T(OPEN_deg) and the device supply voltage V(SUPPLY) is above the threshold V(ADCLOWSUPTH) set by register CONF_ADCLOWSUPTH, the TPS929121-Q1 turns off the current output on the open-circuit channel, pulls ERR pin down with constant current sink to report fault and sets the flag registers including FLAG_OPENCHx, FLAG_OUT and FLAG_ERR to 1. If the device supply voltage V(SUPPLY) is below the threshold V(ADCLOWSUPTH) set by register CONF_ADCLOWSUPTH, open-circuit fault are not detected and reported. If any channel is disabled by CONF_ENCHx to 0, the LED open-circuit diagnostics skip the channel. If one-fails-all-fail protection is enabled by setting EEPROM register EEP_OFAF to 1, all the used output channels are turned off even though the LED open-circuit is only detected on one channel. If one-fails-all-fail protection is disabled by setting EEPROM register EEP_OFAF to 0, only failed channels are turned off. In fail-safe states, the TPS929121-Q1 retries the failed channel with low-current retry pulses every 10 ms. The pulse width T(ODPW) is programmable by CONF_ODPW, and the retry current is set by CONF_ODIOUT. If the retry is succeed, the device automatically releases the ERR pin and clear the flag registers. If the CONF_DIAGENCHx is set to 0, the open-circuit fault is ignored. Possible user case: 1. 2. 3. 4. 5. 6. Supply voltage dip below threshold, triggering false open-circuit fault Real LED open-circuit and recover Extra capacitance caused false open-circuit Dutycycle too short to detect Sequential Turn Error Detection. Only on-time diagnostics only Off-state diagnostics? 8.3.6.7 LED Short-circuit Diagnostics in Fail-Safe State The TPS929121-Q1 has internal analog comparators to monitor all channel outputs with respect to a fixed threshold. If the device has detected channel voltage below threshold, it sets FLAG_SHORTCHx accordingly. The FLAG_OUT and FLAG_ERR are set as well. The short-circuit detection is only enabled during PWM-ON state with programmable minimal pulse width of T(ODPW) + T(SHORT_deg). The T(ODPW) is programmable by register CONF_ODPW. If PWM on-time is less than T(ODPW) + T(SHORT_deg), the device cannot report any short-circuit fault. When the voltage V(OUTx) is below threshold V(SG_th_rising) with duration longer than deglitch timer length of T(ODPW) + T(SHORT_deg), the device turns off the current output on the LED short-circuit channels, pulls the ERR pin down with constant current sink to 30 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 report fault, and sets flag registers including FLAG_SHORTCHx, FLAG_OUT and FLAG_ERR. If any channel is disabled by CONF_ENCHx to 0, the LED short-circuit diagnostics skip the channel. If one-fails-all-fail protection is enabled by setting EEPROM register EEP_OFAF to 1, all the used output channels are turned off even though the LED short-circuit is only detected on one channel. If one-fails-all-fail protection is disabled by setting EEPROM register EEP_OFAF to 0, only failed channels are turned off. In fail-safe states, the TPS929121-Q1 retries the failed channel with a low-current retry pulses in every 10 ms. The pulse width T(ODPW) is programmable by CONF_ODPW, and the retry current is set by CONF_ODIOUT. If the retry is succeed, the device turns on the channel current, automatically release the ERR pin and clears the flag registers. If the CONF_DIAGENCHx is set to 0, the short-circuit fault is ignored. Possible user case: 1. 2. 3. 4. 5. Supply voltage dip below threshold, triggering false single led short-circuit fault LED short to ground and recover LED single LED short and recover Dutycycle too short to detect Extra capacitance caused false short-circuit 8.3.6.8 EEPROM CRC Error in Fail-safe State The TPS929121-Q1 automatically reloads all EEPROM code into the corresponding configuration registers every time after entering the fail-safe state. The TPS929121-Q1 implements a EEPROM CRC check after loading the EEPROM code to configuration register in fail-safe state. The calculated CRC result are sent to register CALC_EEPCRC and compared to the data in EEPROM register EEP_CRC, which stores the CRC code for all EEPROM registers. If the code in register CALC_EEPCRC is not matched to the code in register EEP_CRC, the TPS929121-Q1 turns off all channels output, pulls the ERR pin down with constant current sink to report the fault, and sets the registers including FLAG_EEPCRC and FLAG_ERR to 1. The CRC code for all the EEPROM registers must be burnt into EEPROM register EEP_CRC in the end of production line. The CRC code algorithm is described in EEPROM CRC Error in Normal State. Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 31 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 Table 8-4. Diagnostics Table in Fail-Safe State FAULT TYPE Supply UVLO Low-supply warning DETECTION CRITERIA CONDITIONS FAULT ACTIONS FAULT OUTPUT ERR PIN RECOVERY V(SUPPLY) < V(POR_falling) or V(LDO) < V(LDO_POR_falling) FLAG_POR FLAG_ERR Device switch to Automatically clears POR state flag register and recover upon fault removal. Constant pulled down Device switch to INIT state when all voltage rails are good. Clear fault flag with CLR_POR. V(SUPPLY) < V(ADCLOWSUPTH) Disable fault type FLAG_ADCLOWSUP * FLAG_ERR No action Automatically clear fault flags when supply voltage is above threshold. V(REF) < V(REF_SHORT_th) or I(REF) < I(REF_OPEN_th) Turn off all channels FLAG_REF Constant pulled FLAG_ERR (maskable) down (maskable) Automatically recover, release ERR and clear fault flags upon fault removal. Overtemperature protection T(J) > T(TSD) Turn off all channels FLAG_TSD Constant pulled FLAG_ERR (maskable) down (maskable) Automatically recover, release ERR and clear fault flags upon fault removal. LED open-circuit fault * V(SUPPLY) - V(OUTx) < V(OPEN_th_rising) and V(SUPPLY) > V(ADCLOWSUPTH) PWM pulse width greater than T(ODPW) + T(OPEN_deg) CONF_ENCHx = 1 CONF_DIAGENCHx = 1 Turn off the failed FLAG_OPENCHx channels and Constant pulled FLAG_OUT (maskable) retries every 10 down (maskable) FLAG_ERR (maskable) ms Automatically recover, release ERR and clear fault flags upon fault removal. LED short-circuit fault V(OUTx) < V(SG_th_rising) PWM pulse width greater than T(ODPW) + T(SHORT_deg) CONF_ENCHx = 1 CONF_DIAGENCHx = 1 Turn off the failed FLAG_SHORTCHx channels and Constant pulled FLAG_ERR (maskable) retries every 10 down (maskable) FLAG_OUT (maskable) ms Automatically recover, release ERR and clear fault flags upon fault removal. Reference fault EEPROM CRC error 32 CALC_EEPCRC is different EEP_CRC Turn off all channels FLAG_EEPCRC Constant pulled FLAG_ERR (maskable) down (maskable) Submit Document Feedback Automatically recover, release ERR and clear fault flags upon fault removal. Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 TPS929121-Q1 www.ti.com SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 8.4 Device Functional Modes Initialization State (INIT) Configurable Init Delay EEP_INITTIMER 0h: 0ms 8h: 200us 1h: 50ms 9h: 100us 2h: 20ms Ah: 50us 3h: 10ms Bh: 50us 4h: 5ms Ch: 50us 5h: 2ms Dh: 50us 6h: 1ms Eh: 50us 7h: 500us Fh: 50us or ws rflo S = 1 e v F o er CE Tim OR low WD NF_F in = p CO FS afe il-s Fa = 1 r a S Cle R_F CL Normal State (NORMAL) EEPROM Program Sequence REF pin = high Or EEP_ INTADDR = 0 CONF_EEPGATE = 09h, 02h, 09h, 01h, 02h, 00h CONF_EEPMODE = 1 CONF_STAYINEEP = 1 Supply Good and LDO Good POR State (POR) Fail-Safe State 0 (FAILSAFE0) Under-voltagelock-out Fa u LE FS pin = low FS pin = high WD CO Time NF r o v _ FS FOR erflow pin CE s = H FS = or Cle i gh 1 ar Fail-Safe State 1 CL Fai R_ l-sa (FAILSAFE1) FS fe =1 CONF_STAYINEEP 0: Disable 1: Enable WDTimer CONF_WDTIMER 0h: Disable 8h: 50ms Program State 1h: 200us 9h: 100ms (PROG) 2h: 500us Ah: 200ms 3h: 1ms Bh: 500ms 4h: 2ms Ch: Direct to FS 5h: 5ms Dh: Direct to FS 6h: 10ms Eh: Direct to FS 7h: 20ms Fh: Direct to FS lt R eco ver ed DF au l t Clear Fail-safe CLR_FS = 1 Programmable Output Failure State (OUTFAIL) d e re cov Re t l u t Fa aul DF LE Figure 8-8. Device Functional Mode Statemachine 8.4.1 POR State Upon power up, the TPS929121-Q1 enters power-on-reset (POR) state. In this mode, registers are cleared, outputs are disabled, and the device cannot be accessed through the FlexWire interface. Once both the supply and LDO are above their UVLO threshold, the device switches to Initialization state (INIT). If any of the supply fails below UVLO threshold in other states, the device immediately switches to POR state. 8.4.2 Initialization State The initialization state is designed to allow master controller to have enough time to power up before the device automatically gets into fail-safe states. INIT mode has a configurable delay programmed by 4-bit E2PROM register EEP_INITTIMER. Once the delay counter is reached, the device changes to normal state. In INIT state, the communication between master controller and the TPS929121-Q1 is enabled through FlexWIre interface. If the master controller sets CLR_POR to 1, the device immediately switches to normal state. In Initialization state, device automatically load register map default values, which can be programmed by E2PROM. The channel enable register CONF_ENCHx are all 0 to avoid unwanted blinking. 8.4.3 Normal State Once the TPS929121-Q1 is in normal state, the device operates under master control for LED animation and diagnostics using a FlexWire interface. The TPS929121-Q1 integrates a watchdog timer to monitor the communication on FlexWire. The watchdog timer is programable by a 4-bit register CONF_WDTIMER for 13 options. The timer in TPS929121-Q1 starts to count when there is no instruction received from master controller. The TPS929121-Q1 enters fail-safe states when the timer overflows. The device can be also forced into fail-safe states anytime in normal state by setting CONF_FORCEFS to 1. 8.4.4 Fail-Safe States When the TPS929121-Q1 is entering fail-safe states from normal state, all the registers are set to default value or reloaded from EEPROM. The TPS929121-Q1 provides two sets of channel enable configuration in fail-safe states, programmable by EEP_FS0CHx and EEP_FS1CHx. In fail-safe state 0, the channel-enable register Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated Product Folder Links: TPS929121-Q1 33 TPS929121-Q1 SLVSFZ4A – DECEMBER 2020 – REVISED FEBRUARY 2021 www.ti.com CONF_ENCHx automatically loads code from EEP_FS0CHx; in fail-safe state 1, the channel-enable register CONF_ENCHx automatically loads code from EEP_FS1CHx. The fail-safe state is selective by FS pin voltage. The fail-safe state 1 is selected by pulling the FS pin to high, otherwise the fail-safe state 0 is selected. The flag register FLAG_EXTFS shows the FS input level at real-time. If FS pin input voltage is logic high, the FLAG_EXTFS is set to 1.The device does not reset diagnostics status or FLAG registers when switching between two fail-safe states. Setting CONF_FORCEFS to 1 forces the device into fail-safe state from normal state. The TPS929121-Q1 can quit from fail-safe state to normal state by setting CLR_FS to 1 with FLAG registers cleared. The CONF_CLRLOCK register is automatically set to 1 when the TPS929121-Q1 goes into the fail-safe state to prevent the modification of configuration register by mistake. To get out of fail-safe states to normal state, CONF_CLRLOCK register must be cleared to 0 before setting CLR_FS to 1. The fail-safe states also allows the TPS929121-Q1 operating as standalone device without master controlling in the system. The ERR pin is used as fault indicator to achieve one-fails-all-fail or one-fails-others-on diagnostics requirement. When low quiescent current in fault mode is required, all channels must be set as one-fails-all-fail. In this case, if fault is triggered, the device goes into low current fault mode and disables FlexWire interface to save quiescent current. 8.4.5 Program State The TPS929121-Q1 can enter EEPROM program state by pulling up the REF pin voltage to 5 V or writing multiple configuration registers to enter EEPROM program state. The TPS929121-Q1 ignores diagnostics and fault input except supply or LDO UVLO and overtemperature protection in EEPROM program state. Refer to EEPROM Programming for details of getting into program state. 8.4.6 Programmable Output Failure State The TPS929121-Q1 has a unique programmable output failure state. If there is a failure detected in fail-safe states, the TPS929121-Q1 automatically goes into OUTFAIL state. The EEPROM register EEP_OFAF determines whether the result behavior of output failure is one-fails-all-fail or one-fails-others-on. As different channels may serve different functions, diagnostics requirements are different as well. CONF_DIAGENCHx is able to control diagnostics for every channel. For channels that requires one-fails-all-fail with ERR pin as the fault bus, the fault enable register CONF_DIAGENCHx must be set to 1 and EEP_OFAF to 1. For channels that requires one-fails-others-on in fail-safe states, the fault enable register CONF_DIAGENCHx must be set 1 and EEP_OFAF to 0. In case the channel diagnostics is not needed, set the CONF_DIAGENCHx to 0. Details as described in Table 8-5. The register CONF_DIAGENCHx automatically loads the code from EEPROM register EEP_DIAGENCHx as well as other configuration registers every time entering fail-safe state. 8.4.7 ERR Output The ERR pin is a programmable fault indicator pin. It can be used as an interrupt output to master controller in case there is any fault in normal mode. In fail-safe states, the ERR pin can be used as an output to other ERR pin of other TPS929121-Q1 to realize one-fails-all-fail at system level. The ERR pin is a open-drain output with current limit up to I(pd_ERR). TI recommends a