SLVSBC6C March 2013 – December 2019 TPS84A20
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.