BQ21040: Device behavior when battery is not available

Hello

1) What will behavior of the device if the battery is not connected?---Bill J -- Output voltage will be in battery detect mode with low frequency square wave at about 4V with output current up to fast charge current.

2) As per my understanding, the device will still provide 4.1/4.2 volts with 1Hz (few hundred mV amplitude ) pulse superimposed over it. please correct me if it supposed to behave differently ----Bill J -- This is correct.

3) How device will behave if charging current +load current is more than fast charge current?---Bill J -- Output voltage will drop, unit is in a current limit mode.
3 b) if device will reduce load current or charging current?----Bill J -- Output current is fixed and voltage will drop
3c) if device will reduce the battery current then how it will manage the constant current phase.----Bill J -- The battery will get less current but still get some current during this phase.

Hi Bill

Thanks for thesee update
Previously i was getting behaviour as per the response to question 1 , but since last few days if battery is not inserted i am getting 1.5 V at output , there is no pulse for detection of the battery . I am getting only 1.5 V at the output . I could not able to undersatnd why device is behaving like this.

I have configured my device for providing 70 mA load current , i measured that avarger load current is 7mA , peak should be much below than 20 mA .

Please let me know following
1 How i can debug this ?
2) Can i use the device without battery for long time ? if yes , How long ? can i use device without battery always ?
3) Does use device without baattery will leads to compromise in the performance ? Why ?

When you see the 1.5V what is the input current to bq21040?
You have verified the 1.5V is a DC level and not a square wave?

Hi Bill

This time my input voltage is 5 V , Yes 1.5 V is DC level not square wave.

Also Please let me know following
1) Can i use the device without battery for long time ? if yes , How long ? can i use device without battery always ?
2) Does use device without baattery will leads to compromise in the performance ? Why ?

Hi  Bill  

Please  find the  attached  schematic , i am not   pulling  TS  Pin high , still  can we  use  it  without  battery

for  long time .