ZHCSCC8E March 2014 – July 2018 TPS92601-Q1 , TPS92602-Q1
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
In case of an external short circuit of a boost output supply line to GND, the respective boost controller of the affected channel is no longer able to limit the current through the control loop. This is because of the conductive path from the supply voltage to the shorted output through the inductor and the boost diode.
To protect the external components from excessive currents, the controller of the affected channel interrupts the path to its output by switching off the high-side PWM-dimming PMOS-FET. The interruption occurs as soon as the high-side current-sense amplifier detects a common-mode voltage below 4 V, or when the voltage on the VOUTx pin is below 4 V, or once the high-side current-sense amplifier hits the shorted-output detection threshold V(OPLED). The protection of each channel operates in this way, independently of the other channel (see state-diagram in Figure 13). The device pulls the DIAGx pin of the affected channel high, and the controller of the affected channel remains in this channel-fail state. In order to reset the controller of the affected channel (for example, after removal of a short circuit) there must be one disable-and-enable cycle for the affected channel by pulling the PWMINx pin low for t > t(CH_OFF), and setting it high for t > t(CH_ON).