7.3.8 Output On/Off Inhibit (INH/UVLO)

The INH/UVLO pin provides on and off control of the device. The INH input provides a precise 2.1 V as soon as rising threshold to allow direct logic drive or connection to a voltage divider from a higher voltage source such as PV_IN. Once the INH/UVLO pin voltage exceeds the threshold voltage, the device starts operation. The INH input also incorporates 300 mV (typ) of hysteresis resulting in a falling threshold of 1.8 V. If the INH/UVLO pin voltage is pulled below the threshold voltage, the regulator stops switching and enters low quiescent current state. The INH/UVLO pin cannot be open circuit or floating. The simplest way to enable the operation of the LMZ36002 is to connect the INH/UVLO pin to PVIN pin directly as shown in Figure 27. This connection allows the LMZ36002 device to restart when PV_IN is again within the operation range.

If an application requires controlling the INH/UVLO pin, either drive it directly with a logic input or use an open drain and collector device to interface with the pin and place a 100-kΩ resistor between this pin and PVIN pin as shown in Figure 28. When turning Q1 on applies a low voltage to the inhibit control (INH/UVLO) pin and disables the output of the supply, shown in Figure 29. If Q1 is turned off, the supply executes a soft-start power-up sequence, as shown in Figure 30.

Figure 27. Enabling the Device

Figure 28. Typical Inhibit Control

Figure 29. Inhibit Turn-Off

Figure 30. Inhibit Turn-On