7.4 Device Functional Modes

Table 7-1 provides a quick comparison between the normal and dropout modes of operation.

Table 7-1. Device Functional Mode Comparison

OPERATING MODE

PARAMETER

VIN

IOUT

Normal

VIN > VOUT(nom) + VDO

IOUT < ICL

Dropout

VIN < VOUT(nom) + VDO

IOUT < ICL

7.4.1 Normal Operation

The device regulates to the nominal output voltage under the following conditions:

• The input voltage is greater than the nominal output voltage plus the dropout voltage (VOUT(nom) + VDO)

• The output current is less than the current limit (IOUT < ICL)

• The device junction temperature is greater than –40°C and less than +125°C

7.4.2 Dropout Operation

If the input voltage is lower than the nominal output voltage plus the specified dropout voltage, but all other

conditions are met for normal operation, the device operates in dropout mode. In this mode, the output voltage

tracks the input voltage. During this mode, the transient performance of the device becomes significantly

degraded because the pass transistor is in the ohmic or triode region, and acts as a switch. Line or load

transients in dropout can result in large output voltage deviations.

When the device is in a steady dropout state (defined as when the device is in dropout, VIN < VOUT(NOM) + VDO,

directly after being in a normal regulation state, but not during start up), the pass transistor is driven into the

ohmic or triode region. When the input voltage returns to a value greater than or equal to the nominal output

voltage plus the dropout voltage (VOUT(NOM) + VDO), the output voltage can overshoot for a short period of time

while the device pulls the pass transistor back into the linear region.

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TLV701

SBVS161A – NOVEMBER 2011 – REVISED APRIL 2023

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