ZHCSI59I July 2009 – May 2018 TPS65070 , TPS65072 , TPS65073 , TPS650731 , TPS650732
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
TPS6507x was developed for battery powered applications with focus on lowest shutdown and quiescent current. To achieve this, in shutdown all mayor blocks and the system voltage at the output of the power path (SYS) are turned off and only the input that turns on TPS6507x, pin PB_IN, is supervised. TPS6507x is designed such that only an ON-key on PB_IN is needed pulling this pin LOW to enable TPS6507x. No external pullup is needed as this is integrated into TPS6507x.
Once PB_IN is pulled LOW, the system voltage is ramped and the DC-DC converters and LDOs are started with the sequencing defined for the version used. If PB_IN is released again, TPS6507x would turn off, so a pin was introduced to keep TPS6507x enabled after PB_IN was released. Pin POWER_ON serves this function and needs to be pulled HIGH before the user releases the ON-key (PB_IN = HIGH). This HIGH signal at POWER_ON can be provided by the GPIO of a processor or by a pullup resistor to any voltage in the system which is higher than 1.2 V. Pulling POWER-ON to a supply voltage would significantly reduce the time PB_IN has to be asserted LOW. If POWER_ON is tied to a GPIO, the processor has to boot up first which may take some time. In this case however, the processor could do some additional debouncing, hence does not keep the power enabled if the ON-key is only pressed for a short time. When there is a supply voltage for the battery charger at pins AC or USB, the situation is slightly different. In this case, the power path is enabled and the system voltage (SYS) has ramped already to whatever the voltage at AC or USB is. The dcdc converters are not enabled yet but the start-up could not only be done by pulling PB_IN=LOW but also by pulling POWER_ON=HIGH.
In applications that do not require an ON-key but shall power-up automatically once supply voltage is applied, there are two cases to consider. If TPS6507x is powered from its AC or USB pin (not powered from its BAT pin), POWER-ON just needs to be pulled HIGH to enable the converters. PB_IN must not be tied LOW in this case.
If TPS6507x is powered from its BAT pin, PB_IN needs to be tied LOW to start up the converters.