ZHCSI58C October 2009 – May 2018 TPS65720 , TPS65721
PRODUCTION DATA.
Enables DCDC1 and LDO1 if pulled to GND. Disables DCDC1 and LDO1 if pulled high. There is no internal pull-up resistor, so a resistor is needed externally to SYS. SYS is preferred over BAT because it is powered by either AC or BAT (whichever is higher). If BAT is used, the device may not get a valid HIGH signal if the battery is deeply discharged even when there is voltage at AC.
The input signal is debounced internally by 50 ms. When PB_IN is pulled low, the DCDC1 converter and LDO1 will power up simultaneously. When PB_IN is deasserted, both converters are turned off. To leave the converters on, the HOLD_DCDC1 and HOLD_LDO1 pin need to be asserted high. The HOLD register Bit <CONTROL1:B5> will keep both, DCDC1 and LDO1 enabled if set to 1. For proper operation the PB_IN, HOLD_DCDC1 and HOLD_LDO1 pins must be terminated and must not be left floating.