The TPS929240-Q1 also integrates analog comparators to monitor all outputs with respect to two alternative threshold for single-LED short-circuit diagnostic in FAIL-SAFE state. Setting the register SLSEN to 1 enables the single-LED short-circuit detection.

The single-LED short-circuit detection is only effective during PWM-ON state with programmable minimal pulse width of t_(BLANK) + t_{(SLS_deg)}. The t_(BLANK) is programmable by register BLANK. If PWM on-time is less than t_(BLANK) + t_{(SLS_deg)}, the device cannot report any single-LED short-circuit fault. When the device supply voltage V_(SUPPLY) is below the threshold V_(LOWSUPTH) set by register LOWSUPTH, the single-LED short-circuit is not detected nor reported.

When the voltage V_(OUTXn) is below threshold V_(SLSTHx) with duration longer than deglitch timer length of t_(BLANK) + t_{(SLS_deg)}, and the device supply voltage V_(SUPPLY) is above the threshold V_(LOWSUPTH), the device pulls the ERR pin down with constant current sink to report fault and set flag registers including FLAG_SLSOUTXn, FLAG_OUT and FLAG_ERR. The TPS929240-Q1 provides two alternative threshold V_(SLSTH0) and V_(SLSTH1) for single-LED short-circuit detection selected by SLSTHOUTXn independently for each current output. The V_(SLSTH0) is selected for current OUTXn when LSTHOUTXn is set to 0, however V_(SLSTH1) is selected when SLSLTHOUTXn is set to 1. The actual voltage value for V_(SLSTH0) and V_(SLSTH1) is programmable by two 8-bit registers SLSTH0 and SLSTH1 from 2.5 V to 34.375 V at 125-mV interval. In FAIL-SAFE state, the TPS929240-Q1 shuts down the normal current regulation and PWM duty cycle for the faulty output, then the device sources a pulse current, I_(OUTXn) programed by IOUTXn register to the faulty output every t_{(SLS_Retry)}, 10 ms for retrying. When the voltage V_(OUTXn) of error output rises above threshold V_(SLSTHx) + 275 mV with duration longer than t_(BLANK) + t_{(SLS_deg)} during retrying, or the supply voltage V_(SUPPLY) is below the threshold V_(LOWSUPTH), the device automatically resumes the normal current and PWM dutycycle setup and releases the ERR pin.

The fault is latched in flag registers. When the single-LED short-circuit fault is removed, the master controller must write 1 to register CLRFAULT to clear FLAG_SLSOUTXn, FLAG_OUT and FLAG_ERR. The CLRFAULT automatically returns to 0.