Output Voltage in

normal regulation

Dropout

VOUT = VIN - VDO

Transient response

time of the LDO

Load current

discharges

output

voltage

Time

VGS voltage for

normal operation

VGS voltage in

dropout (pass device

fully on)

VDO

Gate Voltage

Input Voltage

VGS voltage for

normal operation

Input Voltage

Output Voltage

VGS voltage

(pass device

fully off)

20

TPS746

SBVS337A – APRIL 2018 – REVISED DECEMBER 2018

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Copyright © 2018, Texas Instruments Incorporated

Application Information (continued)

Figure 48. Line Transients From Dropout

8.1.5 Reverse Current

As with most LDOs, excessive reverse current can damage this device.

Reverse current flows through the body diode on the pass element instead of the normal conducting channel. At

high magnitudes, this current flow degrades the long-term reliability of the device, as a result of one of the

following conditions:

•

Degradation caused by electromigration

•

Excessive heat dissipation

•

Potential for a latch-up condition

Conditions where reverse current can occur are outlined in this section, all of which can exceed the absolute

maximum rating of VOUT > VIN + 0.3 V:

•

If the device has a large COUT and the input supply collapses with little or no load current

•

The output is biased when the input supply is not established

•

The output is biased above the input supply