Is it OK to reverse-bias an LDO, causing its output voltage to become higher than the input voltage?

If the output voltage of an LDO becomes higher than the input voltage, current flows into the LDO from the output terminal, degrading or destroying the LDO. In cases where this situation could occur, add a bypass diode between the VIN and VOUT terminals or connect a reverse-current blocking diode in series with the power supply line. When you use a reverse-current blocking diode, exercise care as to a voltage drop due to the diode’s forward voltage (VF) in order to ensure that the LDO operates properly over the input voltage range. A diode with low forward voltage and leakage current should be selected, taking the derating of reverse-bias voltage and forward current into consideration.

Figure 1 Example of LDO protection using a reverse-current bypass diode
Figure 1 Example of LDO protection using a reverse-current bypass diode
Figure 2 Example of LDO protection using a reverse-current blocking
Figure 2 Example of LDO protection using a reverse-current blocking

For other LDO regulators, visit the main web page of LDO regulators at:

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