TPS929160-Q1
ZHCSNG0 – APRIL 2023
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7.3.8 Diagnostic and Protection in FAIL-SAFE states
In FAIL-SAFE state, the TPS929160-Q1 also detects all failures and reports the status out by ERR or FLAG
registers. 表 7-8 lists the summary of the fault detection criteria and the device behavior after the fault is
detected. Basically, the TPS929160-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 OFAF can be used to set the fault behavior for LED open-circuit, LED short-circuit and single-LED
short-circuit faults. The one-fails-all-fail behavior is selected when the register OFAF is burnt to 1; otherwise,
the one-fails-others-on behavior is chosen. The TPS929160-Q1 turns off all output channels when any type
of LED fault is detected on any one of output channels for one-fails-all-fail behavior. On the other hand, the
TPS929160-Q1 only turns off the failed channel and keeps all other normal channels on.
In FAIL-SAFE state, the fault flag registers of TPS929160-Q1 still can be accessed again through FlexWire
interface in case the communication is rebuilt.
7.3.8.1 Supply Undervoltage Lockout Diagnostics in FAIL-SAFE states
When VBAT 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. The master
controller can write 1 to register CLRPOR to clear the FLAG_POR and FLAG_ERR, and the CLRPOR bit
automatically returns to 0.
7.3.8.2 Low-Supply Warning Diagnostics in FAIL-SAFE states
The TPS929160-Q1 continuously monitors the SUPPLY voltage and compares the results with internal threshold
V(LOWSUPTH) set by LOWSUPTH for low-supply voltage warning.
If the supply voltage is lower than threshold, the device sets flag registers including FLAG_LOWSUP and
FLAG_ERR to 1.
The fault is latched in flag registers. When the supply voltage rises above low-supply warning threshold, the
master controller must write register CLRFAULT to 1 to reset FLAG_LOWSUP and FLAG_ERR. The CLRFAULT
bit automatically returns to 0.
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(LOWSUPTH), the TPS929160-
Q1 enables LED open-circuit and single-LED short-circuit diagnosis. When V(SUPPLY) is lower than the threshold
V(LOWSUPTH), 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(OUT_drop) at required
current, the TPS929160-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(LOWSUPTH) is programmable from 4 V to 35 V at 1-V interval.
7.3.8.3 Supply Undervoltage Diagnostics in FAIL-SAFE State
The TPS929160-Q1 provides internal analog comparator to monitor the supply voltage for undervoltage
protection in FAIL-SAFE state.
If the supply voltage falls below the internal threshold, V(SUPUV_th_falling), the device pulls the ERR pin low with
constant current sink to report the fault and set flag registers including FLAG_SUPUV and FLAG_ERR to 1.
The supply undervoltage detection is used to disable all current output. When V(SUPPLY) is lower than the
threshold V(SUPUV_th_falling), the device disables every outputs to avoid the unwanted LED flickering or output fault
triggered improperly. When the voltage applied on SUPPLY pin rises above the threshold V(SUPUV_th_rising), the
TPS929160-Q1 enables all current outputs automatically.
The fault is latched in flag registers. When the supply voltage rises above V(SUPUV_th_rising), the TPS929160-Q1
releases ERR pin and the master controller must write register CLRFAULT to 1 to clear FLAG_SUPUV and
FLAG_ERR. The CLRFAULT bit automatically returns to 0.
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Product Folder Links: TPS929160-Q1
English Data Sheet: SLVSG60
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