SLVSFZ4A December   2020  – February 2021 TPS929121-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Device Bias and Power
        1. 8.3.1.1 Power Supply (SUPPLY)
        2. 8.3.1.2 5-V Low-Drop-Out Linear Regulator (VLDO)
        3. 8.3.1.3 Undervoltage Lockout (UVLO) and Power-On-Reset (POR)
        4. 8.3.1.4 Programmable Low Supply Warning
      2. 8.3.2 Constant Current Output
        1. 8.3.2.1 Reference Current With External Resistor (REF)
        2. 8.3.2.2 64-Step Programmable High-Side Constant-Current Output
      3. 8.3.3 PWM Dimming
        1. 8.3.3.1 PWM Dimming Frequency
        2. 8.3.3.2 PWM Generator
        3. 8.3.3.3 Linear Brightness Control
        4. 8.3.3.4 Exponential Brightness Control
        5. 8.3.3.5 External Clock Input for PWM Generator (CLK)
        6. 8.3.3.6 External PWM Input ( PWM0 and PWM1)
      4. 8.3.4 On-chip 8-bit Analog-to-Digital Converter (ADC)
      5. 8.3.5 Diagnostic and Protection in Normal State
        1. 8.3.5.1  Fault Masking
        2. 8.3.5.2  Supply Undervoltage Lockout Diagnostics in Normal State
        3. 8.3.5.3  Low-Supply Warning Diagnostics in Normal State
        4. 8.3.5.4  Reference Diagnostics in Normal State
        5. 8.3.5.5  Pre-Thermal Warning and Overtemperature Protection in Normal State
        6. 8.3.5.6  Communication Loss Diagnostic in Normal State
        7. 8.3.5.7  LED Open-Circuit Diagnostics in Normal State
        8. 8.3.5.8  LED Short-Circuit Diagnostics in Normal State
        9. 8.3.5.9  On-Demand Off-State Invisible Diagnostics
        10. 8.3.5.10 On-Demand Off-State Single-LED Short-Circuit (SS) Diagnostics
        11. 8.3.5.11 Automatic Single-LED Short-Circuit (AutoSS) Detection in Normal State
        12. 8.3.5.12 EEPROM CRC Error in Normal State
        13.       48
      6. 8.3.6 Diagnostic and Protection in Fail-Safe States
        1. 8.3.6.1 Fault Masking
        2. 8.3.6.2 Supply UVLO Diagnostics in Fail-Safe States
        3. 8.3.6.3 Low-supply Warning Diagnostics in Fail-Safe states
        4. 8.3.6.4 Reference Diagnostics at Fail-Safe States
        5. 8.3.6.5 Overtemperature Protection in Fail-Safe State
        6. 8.3.6.6 LED Open-circuit Diagnostics in Fail-Safe State
        7. 8.3.6.7 LED Short-circuit Diagnostics in Fail-Safe State
        8. 8.3.6.8 EEPROM CRC Error in Fail-safe State
        9.       58
    4. 8.4 Device Functional Modes
      1. 8.4.1 POR State
      2. 8.4.2 Initialization State
      3. 8.4.3 Normal State
      4. 8.4.4 Fail-Safe States
      5. 8.4.5 Program State
      6. 8.4.6 Programmable Output Failure State
      7. 8.4.7 ERR Output
      8. 8.4.8 Register Default Data
    5. 8.5 Programming
      1. 8.5.1 FlexWire Protocol
        1. 8.5.1.1 Protocol Overview
        2. 8.5.1.2 UART Interface Address Setting
        3. 8.5.1.3 Status Response
        4. 8.5.1.4 Synchronization Byte
        5. 8.5.1.5 Device Address Byte
        6. 8.5.1.6 Register Address Byte
        7. 8.5.1.7 Data Frame
        8.       77
        9. 8.5.1.8 CRC Frame
        10. 8.5.1.9 Burst Mode
      2. 8.5.2 Registers Lock
      3. 8.5.3 All Registers CRC Check
      4. 8.5.4 EEPROM Programming
        1. 8.5.4.1 Chip Selection by Pulling REF Pin High
        2. 8.5.4.2 Chip Selection by ADDR Pins configuration
        3. 8.5.4.3 EEPROM Register Access and Burn
        4. 8.5.4.4 EEPROM Program State Exit
        5. 8.5.4.5 Reading Back EEPROM
    6. 8.6 Register Maps
      1. 8.6.1 FullMap Registers
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Smart Rear Lamp With Distributed LED drivers
      2. 9.2.2 Design Requirements
      3. 9.2.3 Detailed Design Procedure
      4. 9.2.4 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

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.

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.