SNVSBD1B August   2020  – May 2024 LP8866S-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Logic Interface Characteristics
    7. 5.7 Timing Requirements for I2C Interface
    8.     14
    9. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Control Interface
      2. 6.3.2 Function Setting
      3. 6.3.3 Device Supply (VDD)
      4. 6.3.4 Enable (EN)
      5. 6.3.5 Charge Pump
      6. 6.3.6 Boost Controller
        1. 6.3.6.1 Boost Cycle-by-Cycle Current Limit
        2. 6.3.6.2 Controller Min On/Off Time
        3. 6.3.6.3 Boost Adaptive Voltage Control
          1. 6.3.6.3.1 FB Divider Using Two-Resistor Method
          2. 6.3.6.3.2 FB Divider Using Three-Resistor Method
          3. 6.3.6.3.3 FB Divider Using External Compensation
        4. 6.3.6.4 Boost Sync and Spread Spectrum
        5. 6.3.6.5 Boost Output Discharge
        6. 6.3.6.6 Light Load Mode
      7. 6.3.7 LED Current Sinks
        1. 6.3.7.1 LED Output Current Setting
        2. 6.3.7.2 LED Output String Configuration
        3. 6.3.7.3 LED Output PWM Clock Generation
      8. 6.3.8 Brightness Control
        1. 6.3.8.1 Brightness Control Signal Path
        2. 6.3.8.2 Dimming Mode
        3. 6.3.8.3 LED Dimming Frequency
        4. 6.3.8.4 Phase-Shift PWM Mode
        5. 6.3.8.5 Hybrid Mode
        6. 6.3.8.6 Direct PWM Mode
        7. 6.3.8.7 Sloper
        8. 6.3.8.8 PWM Detector Hysteresis
        9. 6.3.8.9 Dither
      9. 6.3.9 Protection and Fault Detections
        1. 6.3.9.1 Supply Faults
          1. 6.3.9.1.1 VIN Undervoltage Faults (VINUVLO)
          2. 6.3.9.1.2 VIN Overvoltage Faults (VINOVP)
          3. 6.3.9.1.3 VDD Undervoltage Faults (VDDUVLO)
          4. 6.3.9.1.4 VIN OCP Faults (VINOCP)
            1. 6.3.9.1.4.1 VIN OCP Current Limit vs. Boost Cycle-by-Cycle Current Limit
          5. 6.3.9.1.5 Charge Pump Faults (CPCAP, CP)
          6. 6.3.9.1.6 CRC Error Faults (CRCERR)
        2. 6.3.9.2 Boost Faults
          1. 6.3.9.2.1 Boost Overvoltage Faults (BSTOVPL, BSTOVPH)
          2. 6.3.9.2.2 Boost Overcurrent Faults (BSTOCP)
          3. 6.3.9.2.3 LEDSET Resistor Missing Faults (LEDSET)
          4. 6.3.9.2.4 MODE Resistor Missing Faults (MODESEL)
          5. 6.3.9.2.5 FSET Resistor Missing Faults (FSET)
          6. 6.3.9.2.6 ISET Resistor Out of Range Faults (ISET)
          7. 6.3.9.2.7 Thermal Shutdown Faults (TSD)
        3. 6.3.9.3 LED Faults
          1. 6.3.9.3.1 Open LED Faults (OPEN_LED)
          2. 6.3.9.3.2 Short LED Faults (SHORT_LED)
          3. 6.3.9.3.3 LED Short to GND Faults (GND_LED)
          4. 6.3.9.3.4 Invalid LED String Faults (INVSTRING)
          5. 6.3.9.3.5 I2C Timeout Faults
        4. 6.3.9.4 Overview of the Fault and Protection Schemes
    4. 6.4 Device Functional Modes
      1. 6.4.1  State Diagram
      2. 6.4.2  Shutdown
      3. 6.4.3  Device Initialization
      4. 6.4.4  Standby Mode
      5. 6.4.5  Power-line FET Soft Start
      6. 6.4.6  Boost Start-Up
      7. 6.4.7  Normal Mode
      8. 6.4.8  Fault Recovery
      9. 6.4.9  Latch Fault
      10. 6.4.10 Start-Up Sequence
    5. 6.5 Programming
      1. 6.5.1 I2C-Compatible Interface
      2. 6.5.2 Programming Examples
        1. 6.5.2.1 General Configuration Registers
        2. 6.5.2.2 Clearing Fault Interrupts
        3. 6.5.2.3 Disabling Fault Interrupts
        4. 6.5.2.4 Diagnostic Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Full Feature Application for Display Backlight
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1  Inductor Selection
          2. 7.2.1.2.2  Output Capacitor Selection
          3. 7.2.1.2.3  Input Capacitor Selection
          4. 7.2.1.2.4  Charge Pump Output Capacitor
          5. 7.2.1.2.5  Charge Pump Flying Capacitor
          6. 7.2.1.2.6  Output Diode
          7. 7.2.1.2.7  Switching FET
          8. 7.2.1.2.8  Boost Sense Resistor
          9. 7.2.1.2.9  Power-Line FET
          10. 7.2.1.2.10 Input Current Sense Resistor
          11. 7.2.1.2.11 Feedback Resistor Divider
          12. 7.2.1.2.12 Critical Components for Design
        3. 7.2.1.3 Application Curves
      2. 7.2.2 Application with Basic/Minimal Operation
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curves
      3. 7.2.3 SEPIC Mode Application
        1. 7.2.3.1 Design Requirements
        2. 7.2.3.2 Detailed Design Procedure
          1. 7.2.3.2.1  Inductor Selection
          2. 7.2.3.2.2  Coupling Capacitor Selection
          3. 7.2.3.2.3  Output Capacitor Selection
          4. 7.2.3.2.4  Input Capacitor Selection
          5. 7.2.3.2.5  Charge Pump Output Capacitor
          6. 7.2.3.2.6  Charge Pump Flying Capacitor
          7. 7.2.3.2.7  Switching FET
          8. 7.2.3.2.8  Output Diode
          9. 7.2.3.2.9  Switching Sense Resistor
          10. 7.2.3.2.10 Power-Line FET
          11. 7.2.3.2.11 Input Current Sense Resistor
          12. 7.2.3.2.12 Feedback Resistor Divider
          13. 7.2.3.2.13 Critical Components for Design
        3. 7.2.3.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.9.4 Overview of the Fault and Protection Schemes

Table 6-9 Fault and Protection Schemes
FAULT NAME STATUS BIT CONDITION TRIGGER FAULT INTERRUPT ENTER FAULT RECOVERY ACTION
VIN undervoltage VINUVLO_STATUS UVLO voltage falls below 0.787V. Yes Yes Device goes to standby and then attempts to restart once the input voltage rises above threshold.
VIN overvoltage VINOVP_STATUS VIN voltage rises above 43V. Yes Yes Device goes to standby and waits until input voltage falls below threshold before restarting.
VDD undervoltage VDDUVLO_STATUS VDD level falls below VDDUVLO threshold. Yes No Device restarts once VDD level rises above VDDUVLO threshold.
VIN overcurrent VINOCP_STATUS Voltage across RISENSE exceeds 220mV. Yes Yes Device goes to Fault Recovery and then attempts to restart 100ms after fault occurs.
Charge pump fault CP_STATUS Charge pump voltage level is abnormal. Yes Yes Device goes to Fault Recovery and then attempts to restart 100ms after fault occurs.
Charge pump components missing CPCAP_STATUS Charge pump is missing components. Yes No Charge pump is disabled. Charge pump fault will be reported. Device tries to keep normal operation.
Boost sync clock invalid fault BSTSYNC_STATUS Device is enabled while a valid external SYNC clock is running. Then SYNC stops or changes to frequency < 75kHz. Yes No Defaults to internal clock frequency selected by BST_FSET resistor. If BST_SYNC input is held high then spread spectrum is enabled. If BST_SYNC input is held low then spread spectrum is disabled.
CRC error CRCERR_STATUS Factory default configuration for registers, options and trim bits are not correctly loaded from memory. Yes No Device functions normally, if possible.
Boost OVP low BSTOVPLOW_STATUS FB pin voltage rises above VFB_OVPL level. No No Boost stops switching until boost voltage level falls. The device remains in normal mode with LED drivers operational.
Boost OVP high BSTOVPH_STATUS FB pin voltage rises above VFB_OVPH level or DISCHARGE pin voltage rises above VBST_OVPH. Yes Yes Device goes to Fault Recovery and waits until output voltage falls below threshold before restarting.
Boost overcurrent BSTOCP_STATUS FB pin voltages falls below VUVP level for 110ms. Yes Yes Device goes to Fault Recovery and then attempts to start 100ms after fault occurs.
LEDSET detection fault LEDSET_STATUS LEDSET resistor missing or invalid. No No Defaults to 6-channel / 150mA configuration.
MODE detection fault MODESEL_STATUS MODE resistor missing or invalid. No No Defaults to phase-shift PWM mode, I2C address is 0x2A.
FSET detection fault FSET_STATUS BST_FSET or PWM_FSET resistor are missing or an invalid value. No No Device keeps operating at 400-kHz switching frequency for boost converter and 305Hz for PWM dimming frequency.
ISET resistor fault ISET_STATUS ISET pin voltage is pulled down to below 1V due to ISET pin resistor shorted to GND Yes No LED_CURRENT[11:0] is written to 0x3FF. Total LED current limited to 70mA.
Thermal shutdown TSD_STATUS Junction temperature rises above TSD threshold. Yes Yes Device goes to standby and then attempts to restart once die temperature falls below threshold.
Open LED string LED_STATUS OPEN_LED Headroom voltage on one or more channels is below minimum level and boost has adapted to maximum level. Yes No Faulted LED string is disabled and removed from adaptive boost control loop. String is re-enabled next power cycle.
LED internal short LED_STATUS_SHORT_LED Headroom voltage on one or more channels is above the SHORTED_LED_THRESHOLD for > 5ms while the headroom of at least one channel is still below this threshold. Yes No Faulted LED string is disabled and removed from adaptive boost control loop. String is re-enabled next power cycle.
LED short to GND LED_STATUS_GND_LED

During PL FET SOFT START, voltage of one or more used LED output is below VHEADROOM when small test current is injected.

In BOOST_SU and Normal Stage, voltage of one or more used LED output is below VSHORTGND.and keeps still when the corresponding channel is off and small test current is injected.

 Yes Yes Device goes to Fault Recovery and then attempts to restart 100 ms after fault occurs.
Invalid LED string detected INVSTRING_STATUS Configured unused LED output is detected not short to GND. Yes No Device functions normally, if possible.
I2C timeout I2C_ERROR_STATUS Device receives I2C command without STOP signal for 500ms. Yes No Device functions normally and waits for the next I2C command.