ZHCSLS0B July 2022 – April 2024 TPS929240-Q1
PRODUCTION DATA
请参考 PDF 数据表获取器件具体的封装图。
The TPS929240-Q1 integrates LED open-circuit diagnostics to allow users to monitor LED status real time in FAIL-SAFE state. The device monitors voltage difference between SUPPLY and OUTXn to judge if there is any open-circuit failure. The SUPPLY voltage is also monitored in parallel with programmable threshold to determine if supply voltage is high enough for open-circuit diagnostics.
The open-circuit monitor is only effective during PWM-ON state with programmable minimal pulse width greater than t(BLANK) + t(OPEN_deg). The t(BLANK) is programmed by register BLANK. If PWM on-time is less than t(BLANK) + t(OPEN_deg), the device does not report any open-circuit fault. When the device supply voltage V(SUPPLY) is below the threshold V(LOWSUPTH) set by register LOWSUPTH, the LED open-circuit fault is not detected nor reported.
When the voltage difference V(SUPPLY) – V(OUTXn) is below threshold V(OPEN_th_rising) with duration longer than t(BLANK) + t(OPEN_deg), and the device supply voltage V(SUPPLY) is above the threshold V(LOWSUPTH), the TPS929240-Q1 pulls the ERR pin down with constant current sink to report fault and set flag registers including FLAG_OPENOUTXn, FLAG_OUT and FLAG_ERR to 1. In FAIL-SAFE state, the TPS929240-Q1 shuts down the normal current regulation and PWM dutycycle for the error output, then the device sources a current I(RETRY) to faulty output every t(SLS_Retry), 10 ms for retrying. I(RETRY) is programed by IRETRY register. The current I(RETRY) can be calculated with the below equation. When the voltage difference V(SUPPLY) – V(OUTXn) of error output rises above threshold V(OPEN_th_rising) with duration longer than t(BLANK) + t(OPEN_deg), or the supply voltage V(SUPPLY) is above the threshold V(LOWSUPTH), the device automatically resumes the normal current and PWM duty cycle setup and releases the ERR pin.
where
The fault is latched in flag registers. When the open-circuit failure is removed, the master controller must write 1 to CLRFAULT to clear FLAG_OPENOUTXn, FLAG_OUT and FLAG_ERR. The CLRFAULT bit automatically returns to 0.