JAJSJM2B July 2022 – April 2024 TPS929240-Q1
PRODUCTION DATA
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The TPS929240-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 pulls ERR pin down with one pulsed current sink for 50 µs to report the fault and set 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 1 to register CLRFAULT to clear 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 TPS929240-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 TPS929240-Q1 is not able to deliver sufficient current output. The device pulls 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 can 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.