ZHCSTD7A December 2021 – November 2023 BQ79631-Q1
PRODUCTION DATA
To start the Main ADC, the host MCU sets ADC_CTRL1[CS_MAIN_GO] = 1. When the device receives the GO command, it first samples the following settings to determine Main ADC configuration and then operates the Main ADC accordingly. Any change of the settings below requires the MCU to resend another GO command to implement the new settings.
There are two status bits to indicate the Main ADC status:
[MAIN_MODE1:0] | Run Mode | Description |
---|---|---|
0b00 | Stop Main ADC | Stop the Main ADC |
0b01 | 8 RR Run (eight round robin cycles) | Main ADC runs for eight round robin cycles then stops. This gives a single measurement on all VS voltages and all GPIO inputs to the system. Filtered measurements are not effective under run mode. For example, use as a quick burst read when MCU is periodically awake during system idle state. |
0b10 | Continuous Run | Main ADC runs in continuous mode and stops if [MAIN_MODE1:0] = 0b00 and a GO is sent. For example, must use this mode if LPF is enabled. Also use in diagnostic operation. |
The level shifter is enabled when device enters ACTIVE mode. MCU shall wait for tAFE_SETTLE time before starting the Main ADC whenever the device enters ACTIVE mode.
The Main ADC operates in ACTIVE mode only. If the ADC is running while the device goes into SLEEP, the Main ADC will be “frozen” (that is, ADC is stopped but device still remembers the operational state). When the device returns to ACTIVE mode without any digital reset event, the Main ADC will restart and continues from its “pre-frozen” state. In this condition, the VS voltage measurements are off during the tAFE_SETTLE time because input voltage to the ADC is not settled yet. MCU can ignore these measurements or send a new GO command to restart the Main ADC after tAFE_SETTLE.