The TPS7A43 features a precision enable circuit. The enable pin (EN) is active high; thus, enable the device by forcing the voltage of the enable pin to exceed the V_EN(HI) voltage; see the Section 6.5 table. Turn off the device by forcing the voltage of the enable pin to drop below the V_EN(LOW) voltage; see the Section 6.5 table. EN is pulled high by a 50-nA current source; therefore, EN can be left floating to enable the device. Board-level leakage on the order of tens of nanoamperes can cause the EN pin to be pulled low when EN is left floating, so care must be taken to minimize leakage if this functionality is used.

If this pin is tied to the IN pin, the input voltage must not exceed 18 V; see the Section 6.3 table.

As shown in Figure 7-3, an external resistor divider circuit can be used to enable the device using the input voltage.

Figure 7-3 Enable the Device Using the Input Voltage

The V_EN(HI) (maximum) and V_EN(LOW) (minimum) thresholds along with the application input voltage can be used to set the R₁ to R₂ resistor divider ratio. The values of the R₂ and R₁ resistors can also be optimized to minimize the leakage current through the divider.