mcqn / my-bikes-got-led

My Baby's Got LED, bike edition
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Can we terminate the QON pin on the BQ25895M battery management IC #22

Closed huffeec closed 2 days ago

huffeec commented 2 months ago

Issue to record discussion about what we want to do with the QON switch,

From the datasheet

"8.2.10 BATET (Q4) Control 8.2.10.1 BATFET Disable Mode (Shipping Mode) To extend battery life and minimize power when system is powered off during system idle, shipping, or storage, the device can turn off BATFET so that the system voltage is zero to minimize the battery leakage current. When the host set BATFET_DIS bit, the charger can turn off BATFET immediately or delay by tSM_DLY as configurated by BATFET_DLY bit.

8.2.10.2 BATFET Enable (Exit Shipping Mode) When the BATFET is disabled (in shipping mode) and indicated by setting BATFET_DIS, one of the following events can enable BATFET to restore system power:

  1. Plug in adapter
  2. Clear BATFET_DIS bit
  3. Set REG_RST bit to reset all registers including BATFET_DIS bit to default (0)
  4. A logic high to low transition on QON pin with tSHIPMODE deglitch time to enable BATFET to exit shipping mode

8.2.10.3 BATFET Full System Reset The BATFET functions as a load switch between battery and system when input source is not plugged-in. By changing the state of BATFET from off to on, system connects to SYS can be effectively have a power-on-reset. The QON pin supports push-button interface to reset system power without host by change the state of BATFET. When the QON pin is driven to logic low for tQON_RST while input source is not plugged in and BATFET is enabled (BATFET_DIS=0), the BATFET is turned off for tBATFET_RST and then it is re-enabled to reset system power. This function can be disabled by setting BATFET_RST_EN bit to 0."

huffeec commented 2 days ago

Fixed by #25