10

TLV717P

SBVS176B – OCTOBER 2011 – REVISED APRIL 2016

www.ti.com

Product Folder Links: TLV717P

Submit Documentation Feedback

Copyright © 2011–2016, Texas Instruments Incorporated

Feature Description (continued)

7.3.2 Shutdown

The enable pin (EN) is active high. The device is enabled when the voltage at the EN pin goes above 0.9 V. This

relatively lower voltage value required to turn the LDO on can be exploited to power the LDO with a GPIO of

recent processors whose GPIO logic 1 voltage level is lower than traditional microcontrollers. The device is

turned off when the EN pin is held at less than 0.4 V. When shutdown capability is not required, EN can be

connected to the IN pin.

7.3.3 Undervoltage Lockout (UVLO)

The TLV717P uses an undervoltage lockout circuit (UVLO = 1.6 V) to keep the output shut off until the internal

circuitry operates properly.

7.4 Device Functional Modes

7.4.1 Normal Operation

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

•

The input voltage has previously exceeded the UVLO rising voltage and has not decreased below the UVLO

falling threshold.

•

The input voltage is greater than the nominal output voltage added to the dropout voltage.

•

The enable voltage has previously exceeded the enable rising threshold voltage and not decreased below the

enable falling threshold.

•

The output current is less than the current limit.

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 condition, the output

voltage is the same the input voltage minus the dropout voltage. The transient performance of the device is

significantly degraded because the pass device is in a triode state and no longer controls the current through the

LDO. Line or load transients in dropout may result in large output voltage deviations.

7.4.3 Disabled

The device is disabled under the following conditions:

•

The input voltage is less than the UVLO falling voltage, or has not yet exceeded the UVLO rising threshold.

•

The enable voltage is less than the enable falling threshold voltage or has not yet exceeded the enable rising

threshold.

When the device is disabled, the active pulldown resistor discharges the output.

Table 1 lists the conditions that lead to the different modes of operation.

Table 1. Device Functional Mode Comparison

OPERATING MODE

PARAMETER

Normal mode

Dropout mode

Disabled mode

(any true condition disables

the device)

—