ZHCSPC2C September 2021 – January 2023 BQ25180
PRODUCTION DATA
The device also offers the option to control SYS through the I2C SYS_MODE bits. These bits can force SYS to be supplied by BAT instead of IN (even if VIN > VBAT + VSLEEP), disconnect SYS from either supply, pull SYS down or leave it floating. The table below shows the device behavior based on SYS_MODE setting:
| SYS_MODE | DESCRIPTION | SYS SUPPLY | SYS PULLDOWN |
|---|---|---|---|
00 | Normal Operation | IN or BAT | Off except during HW reset |
01 | Force BAT power (IN disconnected) | BAT | Off except during HW reset |
10 | SYS Off –Floating | None | Off |
11 | SYS Off – Pulled Down | None | On |
SYS_MODE = 00
This is the default state/normal operation of the device. SYS will be powered from IN if VIN > VUVLO, VIN > VBAT + VSLEEPZ, and VIN < VIN_OVP. SYS will powered by BAT if these conditions are not met. SYS will only be disconnected from IN or BAT and pulled down when a HW Reset occurs or the device goes into Ship mode.
SYS_MODE = 01
When this configuration is set, SYS will be powered by BAT if VBAT > VBUVLO regardless of VIN state. This allows the host to minimize the current draw from the adapter while it is still connected as needed in the system. If SYS_MODE = 01 is set while VBAT < VBUVLO, the SYS_MODE = 01 setting will be ignored and the device will go to SYS_MODE = 00. In the same manner, if the adapter (VIN) is removed and then connected the device will also switch to SYS_MODE = 00. This prevents the device from needing a POR in order to restore power to the system thereby allowing battery charging. If SYS_MODE = 01 is set during charging, charging will be stopped and the battery will start to provide power to SYS as needed. The behavior is similar to that when the input adapter is disconnected.
SYS_MODE = 10
When this configuration is set, SYS will be disconnected and left floating. The device remains on and active. Toggling VIN(VIN <VINUVLO) will reset SYS_MODE to 00.
SYS_MODE = 11
When this configuration is set, SYS will be disconnected and pulled down to ground. Toggling VIN will reset SYS_MODE to 00.