We have a question about TLV743P.
Question 1.
We try to use TLV743P + schottky diode to protect reverse current.
Are there any problem?
And are there specs that can be judged from the datasheet?
We are concerned that IR of schottky diode influences operation of TLV743P.
IR of schottky diode is 100µA or 1000µA Which is better?
Question 2.
Do you know good solution of reverse current protection in using TLV743P?
Best regards,
Takahiro Nishizawa
Hi Takahiro,
Your intended method of placing a Schottky diode from OUT to IN is a common method for protecting an LDO from reverse current. This diode provides a robust path for the reverse current in the event that Vout should exceed Vin. The low forward voltage of a Schottky diode allows for the external diode to begin conducting before the internal parasitic body diode.
Using a Schottky diode in this way will protect the LDO from the reverse current but does have a few tradeoffs. For instance any reverse leakage through the Schottky will provide a path from Vin to Vout and therefore slightly degrade the PSRR.
If your application has enough headroom (Vin - Vout), another method to protect upstream devices from reverse current is to place a diode in series before the input capacitor of the LDO. The diode must be placed before the input capacitor of the LDO so that any reverse current through the LDO will charge the input capacitor and raise the voltage local to the IN pin of the LDO. Once Vout no longer exceeds Vin reverse current will not flow.
Very Respectfully,
Ryan
