ZHCSL07C September 2019 – August 2021 TPS8802
PRODUCTION DATA
The microcontroller LDO (MCU LDO) powers the internal digital input and output buffers (IO buffers) and external MCU that controls and programs the TPS8802. Connect a 1-µF capacitor to VMCU to stabilize the output. The MCU LDO can be programmed to output 1.5 V, 1.8 V, 2.5 V, and 3.3 V. The default MCU LDO setting is determined by the configuration on the MCUSEL pin (see Table 8-1). After the device is powered, the MCU LDO voltage can be changed using the VMCUSET register. The MCU LDO can also be disabled using the MCU_DIS register.
The MCU LDO output VMCU powers the IO buffers on SCL, SDA, CSEL, INT_MCU, GPIO, LEDEN, HBEN, and HORNFB. The IO buffers level shift signals from the digital core to a level suitable for the microcontroller and signals from the microcontroller to a level suitable for the digital core. In general, connect VMCU to the microcontroller supply voltage to guarantee logic level compatibility. If the MCU LDO is disabled, connect an external supply to VMCU. This external supply can be a 3-V battery. Connecting a 3-V battery directly to VMCU allows the MCU LDO to be disabled, saving some power in the system. When a 3-V battery is connected to VMCU, set the MCU LDO to 1.5 V or 1.8 V on power-up. The battery voltage overrides the MCU LDO without excess power draw.
The MCU LDO has a power good signal MCU_PG that indicates whether the MCU LDO is above 85% the regulation voltage. A 125-µs deglitch filter prevents noise from affecting the MCU_PG signal. If MCU_PG is low after 10 ms of changing the MCU LDO voltage or enabling the MCU LDO, the MCU_ERR flag is set high. If the MCU_ERR flag is high and MCUERR_DIS is low, the MCU LDO fault state is entered. See Section 8.4.2.1 section for more information.