EN is a 3-pin header used to enable or disable the TPS7A21.

The center pin of the 3-pin header is tied to the TPS7A21 EN input. When the 2-pin shunt is placed across the top two pins of the header, VIN is shorted to EN, and the TPS7A21 is enabled. When the 2-pin shunt is placed across the bottom two pins of the header, GND is shorted to EN, and the TPS7A21 is disabled. Alternatively, the 3-pin header can remain floating. The TPS7A21 includes an internal smart enable pulldown resistor, which ties the EN pin to GND through an internal 500-k? resistor. If the 3-pin header is floating, the TPS7A21 remains disabled.

When driving the EN terminal with an off-board supply or signal generator, the applied voltage must be kept between 0 V and 6.5 V.