LDL112 datasheet(10/32 Pages) STMICROELECTRONICS

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Application information

LDL112

10/32

DocID026319 Rev 2

6.3

Reverse current protection

The device avoids the reverse current to flow from output to input during any operating

condition (with enable pin in high or low status).The reverse current protection acts in

particular during fast turning on/off operations or when another power supply (with higher

voltage than the input one) is connected to the output port. If a power supply with lower

voltage than the LDO output voltage is connected to VOUT pin, LDO enters the current

protection status, causing high power dissipation.

In the application, the LDL112 reverse current protection acts in the following cases:

Off-state, EN pin is at GND level, VOUT > [VIN + 100 mV]. In this case the device

power pass element (MOSFET) is off, the bulk and gate are switched to VOUT and

therefore all possible current paths from VOUT to VIN are interrupted.

On-state, EN pin is at high level and VOUT > VOUT(nominal). In this condition, VOUT is

higher than the nominal level, so the device op-amp works in open loop and the power

element is off. VGS is zero, the bulk and gate are switched to VOUT (where VOUT > [VIN +

100 mV]) therefore all possible current paths from VOUT to VIN are interrupted.

On-state, EN pin is at high level and VOUT< VOUT(nominal). In this condition VOUT is

lower than the nominal level, so the op-amp works in open loop with the power

MOSFET on. VGS is maximal so the power channel conducts with very low RDS(on).

When VOUT > VIN the current can flow from VOUT to VIN until the condition VOUT > (VIN +

100 mV) is reached.

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