Tool/software: Code Composer Studio
Hi TI guys:
We use BQ40Z60 in Taurus BBU project. Recently there is a urgent issue about Taurus. Taurus is seated in Riptide platform, which is used to offer energy when AC is loss. The full charge voltage in Taurus is about 11.6V. But in Riptide platform, the voltage is about 12.2V-12.1V. Taurus is connected to Riptide through a Oring FET. So in normal case, Taurus will not discharge. The discharge current is about 40mA or more.
But the issue is that Taurus discharges when AC is good and V12 net in Riptide is also higher than BBU output voltage. After our initial analysis, charger in this event works abnormally. It switches high side FET and low side FET during this event. I suppose the discharge circuit is through charger circuit.
Charger is controlled by BQ40Z60. What we expect is charger works during charge process and re-works when recharge conditions are triggered. But it seems it regulates voltage randomly, which causes big problem for us. And it doesn’t align with our expectation.
I want to ask:
What is the charger working algorithm?
What are the recharge conditions?
What is the control loop of charger?
Why does it start to switch abnormally?
How to solve this problem?
Why doesn't charger close when recharge is completed and charge FET is closed?
I attach our waveforms, schematic and FW image.
CH1: PSU output
CH2: BBU output
CH3: BBU internal voltage before ORing inside BBU
CH4: BBU ON_BAT
CH1: Q57_G
CH2: Q60_G
CH3: Q1_G
CH4: BBU ON_BAT
I hope I can get quick response. charger problem.zip
Thanks!
