INH/UVLO

STSEL

AGND

Q1

INH

Control

SS/TR

21

TPS84A20

www.ti.com

SLVSBC6C – MARCH 2013 – REVISED DECEMBER 2019

Product Folder Links: TPS84A20

Submit Documentation Feedback

Copyright © 2013–2019, Texas Instruments Incorporated

10.16 Output On/Off Inhibit (INH)

The INH pin provides electrical on/off control of the device. Once the INH pin voltage exceeds the threshold

voltage, the device starts operation. If the INH pin voltage is pulled below the threshold voltage, the regulator

stops switching and enters low quiescent current state.

The INH pin has an internal pullup current source, allowing the user to float the INH pin for enabling the device. If

an application requires controlling the INH pin, use an open drain/collector device, or a suitable logic gate to

interface with the pin.

Figure 29 shows the typical application of the inhibit function. The Inhibit control has its own internal pullup to VIN

potential. An open-collector or open-drain device is recommended to control this input.

Turning Q1 on applies a low voltage to the inhibit control (INH) pin and disables the output of the supply, shown

in Figure 30. If Q1 is turned off, the supply executes a soft-start power-up sequence, as shown in Figure 31. A

regulated output voltage is produced within 2 ms. The waveforms were measured with a 5-A constant current

load.

Figure 29. Typical Inhibit Control

Figure 30. Inhibit Turn-Off

Figure 31. Inhibit Turn-On