Bq2060a

Hello Mr. Chen,

The bq2060A will always reset when waking from low-power storage mode, but it will normally be a partial reset and not a full reset.  However, there is one condition that might cause a full reset.  When waking, if only one of SMBD or SMBC lines is pulled high, but the other line is held low, and the condition persists for at least 3.5 seconds, the gauge will see a bus busy and will not be able to read the EEPROM.  This will cause a watchdog reset and the part will see a full reset.

If the gauge does not have 1Meg (or less) pull down resistors on SMBC and SMBD, then the lines may float and not remain at logic 0 condition after receiving the low-power storage command.  If one of the communication lines floats to a high while the other is still low, then the gauge may be waked up with a full reset.  The bq2060A cannot be expected to remain in low-power storage mode while the pack is in storage if there are not pull-down resistors to guarantee that SMBC and SMBD remain low.

When waking the part from low-power storage, both SMBC and SMBD should be pulled high.  If only one line is pulled high and is held high, the gauge will do a full reset.  If only one line is momentarily pulled high for less than ~2.5 seconds and then allowed to go back to a low state, the gauge will wake from low-power storage, but will not do a full reset, as the gauge is designed to grant access to the EEPROM if both SMBC and SMBD are low for greater than 2.15 seconds.

In summary, to eliminate this issue, make sure there are 1Meg pull down resistors installed on both SMBC and SMBD and when waking the bq2060A from low-power storage, make sure both SMBC and SMBD are both pulled high at the same time, or within ~2 seconds of each other.

Bill