I am using the TPS74201 LDO. I plan to possibly crowbar the input voltage. I looked through the datasheet for any information regarding what the device can handle as far as reverse currents and duration, but couldn't find anything. I know there must be some limitation as to how much capacitance you can have on the output before the reverse current will effect the chip. I simulated the Pspice model from the TI website, with a protection diode from the output to the input. It showed that most of the crowbared current flowed through the device and not the protection diode. Do these series of LDOs have reverse current protection and to what limitations?
The TPS74201 does not have reverse current protection. If the input voltage is lower than the output voltage then current will flow from the output to the input via the paracitic body diode of the series mosfet. The body diode of the mosfet can handle the same amount of current as in the forward direction (ie 1.5Amps for the TPS74201). However, the power dissipation will be much higher since there will be a 1.2V diode drop for this current rather than the mosfet drain to source resistance so you will need to check if the package can thermally handle the reverse currents if the reverse currents are going to be continuous.
A straight crowbar on the input will not provide any limit to the reverse currents. You may need to add some series resistance with the crow bar to keep the peak currents below 1.5A during clamping. If you are trying to shunt the reverse currents with an external diode then the external diode should be a schottky.
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