INH/UVLO

AGND

Q1

INH

Control

SLVSAZ4

– OCTOBER 2011

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 pull-up 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. Do not place an external pull-up resistor on this pin. Figure 22 shows the typical application

of the inhibit function.

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

shown in Figure 23. If Q1 is turned off, the supply executes a soft-start power-up sequence, as shown in

Figure 24. The waveforms were measured with a 3-A constant current load.

Figure 22. Typical Inhibit Control

Figure 23. Inhibit Turn-Off

Figure 24. Inhibit Turn-On

Copyright

© 2011, Texas Instruments Incorporated

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Product Folder Link(s): TPS84610