I am using a bq24074, driving IN with a 5V 2A wall adapter and a 2000mAhr batter connected to BAT. OUT drives a tps63020 buck/boost to make a 5V 1A output.
The bq24074 is configured as per the data sheet "Charger Design" example:
CE*, TMR, EN1 = GND
EN2 = OUT (4V)
TS = 10K to GND
ILIM = 1.18 K to GND (input limit 1.3A)
ISET = 1.13K to GND (fast charge 800mA)
ITERM = 4.12K to GND (term at 110mA)
I have managed to damage several BQ24074's such that after several discharge/charge cycles, the chip will no longer charge the battery when the wall adapter is applied. Also, the PGOOD LED will no longer light when the adapter is applied.
After the first few chips were damaged, I determined that the 5V load "startup current" was near 4.5A and lasted several hundred mS. This was enough for BQ24074 to go into current limit mode then restart, then current limit, etc, with no battery was attached. I've fixed this startup current issue and was hopeful that it would stop stressing the BQ24074, but today I had another one fail.
The latest chip worked for 5 discharge/charge cycles before it no longer charges. I am apparently over-stressing the device but I do not know why.
This time the battery was about 3.1V, the 5V load about 700mA, so the BAT input current was about ~1.3A when the wall adapter was connected. The charge LED never lit and the battery voltage continued to decrease since the BAT path still works.
At this point, the IN pin sinks 25uA, near it's standby current, but suggests IN is still connected to the chip (no bad solder joint for example).
Have I violated some spec here?
