LMZ31707_14 Datasheet, PDF (19/34 Pages) Texas Instruments – 7A SIMPLE SWITCHER® Power Module with 2.95V-17V Input and Current Sharing in QFN Package

LMZ31707
www.ti.com
SLVSBV7A – JUNE 2013 – REVISED AUGUST 2013
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. Using a voltage superviser to control the INH pin allows control of the turn-on and turn-off
of the device as opposed to relying on the ramp up or down if the input voltage source.
Figure 27 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, shown in Figure 28. If Q1 is turned off, the supply
executes a soft-start power-up sequence, as shown in Figure 29. A regulated output voltage is produced within
2 ms. The waveforms were measured with a 5-A constant current load.
INH
Control
INH/UVLO
Q1
AGND STSEL SS/TR
Figure 27. Typical Inhibit Control
Figure 28. Inhibit Turn-Off
Figure 29. Inhibit Turn-On
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