Hello,
My name is Simeon Aleksandrov, I am an FAE intern at TI BeNeLux.
I was interested to know what is the short circuit behavior of the TPS785
Best Regards,
Simeon Aleksandrov
Hi Simeon,
1) TPS785-Q1 has a foldback-brickwall hybrid current limiting scheme. The way it works is as shown below. (1) If the load impedance goes low enough for the load current to reach I_CL, the output voltage begins to droop, and the output voltage will settle to the voltage required to supply I_CL with the given load impedance. In region (1) the output voltage is V_OUT(NOM) > VOUT > V_FOLDBACK. If the load impedance continues to fall, the foldback region (2) will be reached and both the output voltage and output current will be reduced to limit power dissipation in the device. If the load impedance goes to zero (i.e. a short condition has been reached), the output voltage goes to zero and the output current is constant at I_SC. If the short/low impedance load is removed the device will resume regulation without a reset.
2) The output capacitor should be rated down to at least the operating temperature. With that said, the recommended output capacitor (1uF min for TPS785-Q1) includes 50% derating, which is due to temperature variations and DC bias. Capacitor datasheets should specify the DC bias and temperature derating, so the customer needs to be sure the minimum 0.47uF effective capacitance requirement in note (1) of the ROC table is met.
Regards,
Nick
