SNVA966 July   2020  – MONTH  LP8864-Q1 , LP8864S-Q1 , LP8866-Q1 , LP8866S-Q1

 

  1.   Trademarks
  2. 1Fault Handling Routine
  3. 2Different Fault and Diagnostic Handling Method Recommendation
    1. 2.1 Different Fault Handling Method
      1. 2.1.1 System Brightness Derating
      2. 2.1.2 System-Level Unrecoverable Critical Fault
      3. 2.1.3 System-Level Sustainable Fault
    2. 2.2 Different Diagnostic Wrong Information Handling Method
      1. 2.2.1 System-Level Critical Wrong Diagnostic Information
      2. 2.2.2 System Level Sustainable Wrong Diagnostic Information
  4. 3Summary
  5.   A Fault-Related Functions
    1.     A.1 Protection and Fault Detections
      1.      A.1.1 Supply Faults
        1.       A.1.1.1 VIN Undervoltage Faults (VINUVLO)
        2.       16
        3.       A.1.1.2 VIN Overvoltage Faults (VINOVP)
        4.       A.1.1.3 VDD Undervoltage Faults (VDDUVLO)
        5.       A.1.1.4 VIN OCP Faults (VINOCP)
        6.       A.1.1.5 Charge Pump Faults (CPCAP, CP)
        7.       A.1.1.6 Boost Sync Clock Invalid Faults (BSTSYNC)
        8.       A.1.1.7 CRC Error Faults (CRCERR)
      2.      A.1.2 Boost Faults
        1.       A.1.2.1 Boost Overvoltage Faults (BSTOVPL, BSTOVPH)
        2.       A.1.2.2 Boost Overcurrent Faults (BSTOCP)
        3.       A.1.2.3 LEDSET Resistor Missing Faults (LEDSET)
        4.       A.1.2.4 MODE Resistor Missing Faults (MODESEL)
        5.       A.1.2.5 FSET Resistor Missing Faults (FSET)
        6.       A.1.2.6 ISET Resistor Out of Range Faults (ISET)
        7.       A.1.2.7 Thermal Shutdown Faults (TSD)
      3.      A.1.3 LED Faults
        1.       A.1.3.1 Open LED Faults (OPEN_LED)
        2.       A.1.3.2 Short LED Faults (SHORT_LED)
        3.       A.1.3.3 LED Short to GND Faults (GND_LED)
        4.       A.1.3.4 Invalid LED String Faults (INVSTRING)
        5.       A.1.3.5 I2C Timeout Faults
      4.      A.1.4 Overview of the Fault and Protection Schemes
    2.     A.2 Programming Examples
      1.      A.2.1 Clearing Fault Interrupts
      2.      A.2.2 Disabling Fault Interrupts
      3.      A.2.3 Diagnostic Registers

A.1.4 Overview of the Fault and Protection Schemes

Table 4-1 Fault and Protection Schemes
FAULT NAMESTATUS BITCONDITIONTRIGGER FAULT INTERRUPTENTER FAULT RECOVERYACTION
VIN undervoltageVINUVLO_STATUSUVLO voltage falls below 0.787 V.YesYesDevice goes to standby and then attempts to restart once the input voltage rises above threshold.
VIN overvoltageVINOVP_STATUSVIN voltage rises above 43 VYesYesDevice goes to standby and waits until input voltage falls below threshold before restarting.
VDD undervoltageVDDUVLO_STATUSVDD level falls below VDDUVLO threshold.YesNoDevice restarts once VDD level rises above VDDUVLO threshold.
VIN overcurrentVINOCP_STATUSVoltage across RISENSE exceeds 220 mVYesYesDevice goes to standby and then attempts to restart 100 ms after fault occurs.
Charge pump faultCP_STATUSCharge pump voltage level is abnormal.YesYesDevice goes to standby and then attempts to restart 100 ms after fault occurs.
Charge pump components missingCPCAP_STATUSCharge pump is missing components.YesNoCharge pump is disabled. Charge pump fault will be reported. Device tries to keep normal operation
Boost sync clock invalid faultBSTSYNC_STATUSDevice is enabled while a valid external SYNC clock is running. Then SYNC stops or changes to frequency <75kHzYesNoDefaults 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 errorCRCERR_STATUSFactory default configuration for registers, options and trim bits are not corrected loaded from memoryYesNoDevice functions normally, if possible.
Boost OVP lowBSTOVPLOW_STATUSFB pin voltage rises above VFB_OVPL levelNoNoBoost stops switching until boost voltage level falls. The device remains in normal mode with LED drivers operational.
Boost OVP highBSTOVPH_STATUSFB pin voltage rises above VFB_OVPH level or DISCHARGE pin voltage rises above VBST_OVPHYesYesDevice goes to standby and waits until output voltage falls below threshold before restarting.
Boost overcurrentBSTOCP_STATUSFB pin voltages falls below VUVP level for 110 msYesYesDevice goes to standby and then attempts to start 100 ms after fault occurs.
LEDSET detection faultLEDSET_STATUSLEDSET resistor missing or invalidNoNoDefaults to -channel / mA configuration
MODE detection faultMODESEL_STATUSMODE resistor missing or invalidNoNoDefaults to phase-shift PWM mode, I2C address is
FSET detection faultFSET_STATUSBST_FSET or PWM_FSET resistor are missing or an invalid valueNoNoDevice keeps operating at 400kHz switching frequency for boost converter and 305Hz for PWM dimming frequency.
ISET resistor faultISET_STATUSISET pin voltage is pulled down to below 1V due to ISET pin resistor shorted to GNDYesNoLED_CURRENT[11:0] is written to 0x3FF. Total LED current limited to 65mA.
Thermal shutdownTSD_STATUSJunction temperature rises above TSD threshold.YesYesDevice goes to standby and then attempts to restart once die temperature falls below threshold.
Open LED stringLED_STATUS OPEN_LEDHeadroom voltage on one or more channels is below minimum level and boost has adapted to maximum level.YesNoFaulted LED string is disabled and removed from adaptive boost control loop. String is re-enabled next power cycle.
LED internal shortLED_STATUS_SHORT_LEDHeadroom voltage on one or more channels is above the SHORTED_LED_THRESHOLD for > 5 ms while the headroom of at least one channel is still below this threshold.YesNoFaulted LED string is disabled and removed from adaptive boost control loop. String is re-enabled next power cycle.
LED short to GNDLED_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

YesYesDevice goes to standby and then attempts to restart 100 ms after fault occurs.
Invalid LED string detectedINVSTRING_STATUSConfigured unused LED output is detected not short to GND.YesNoDevice functions normally, if possible.
I2C timeoutI2C_ERROR_STATUSDevice receives I2C command without STOP signal for 500 msYesNoDevice functions normally and waits for the next I2C command.