BQ2962: BQ2962 OUT-pin

Thomas,

If an undervoltage condition is detected on any of the cells, the regulated output is disabled. The OUT pin is not driven high.

The behavior associated with an undervoltage condition is described in the data sheet in the section 8.4.3. Figures 22 and 23 show the behavior of the REG and OUT pins in an undervoltage condition. As you can see by the diagram, the REG pin is inverted, and the OUT pin remains low. To return to normal mode after this condition, simply raise all of the cell voltages above VUVREG + VUVHYS.

Hope this helps clear things up.

Hi Shawn,

thanks for your answer. But the component don't work like this in practice. I build up the circuit and measured the OUT pin. It don't remains low, it switches to high by an undervoltage condition.

Now i want to know, why?  And is it a safe function or a fault.

Kind regards

Thomas

Thomas,

Could you give me some more details about this situation? I would like to know:

1. What are the values of each of the cells when you observe the undervoltage condition? Are any of them experiencing overvoltage?
2. What is the status of the REG pin when this undervoltage condition occurs? It should be driven low. 

Hi Shawn,

thanks for your mail, please see my answers below:

1. Two cells are connected. V3 and V4 are shorted. In undervoltage condition one cell has 2,5V the other eg.3,5V. No Matter which cell voltage is low. No cell reaches the overvoltage limit of 4,55V for the BQ296217.
2. The REG-Output is not in use in my application. I tried to measure the output, but I can’t detect any output voltage in normal operation and in undervoltage condition too.

 For better understanding i send you a part of our application schematic:

Best regards