We have designed a battery charger by using LTC4020. It has 8 NiMh batteries and each has capacity 4500mAh and want to charge them at 2.3A max.
Input Voltage: 10-16V
Output Voltage: 8-14V
Max Charge Current: 2.3A
f0 = ~500Khz
Mode = CC (mode pin floating)
When I test the charger, I set the LTC_RNG pin to have 10% of full charging current, I measured charge current around 240mA which is good.
I set RNG to have 50%, we get charge current as around 1.2A which is ok too.
But when I set RNG to have 100%, we are getting only 400mA charge current while the expected is around 2.3A. (At this time RNG pin has 3V by internal source)
Pins status during charging are same and observed as STAT1 = 0 and STAT=3.5V at any level.
Any advice is highly appreciated about potential problems.
When attempting full-charge-current operation, what measurements have you made besides charge current? Is the charge-current measurement average current? RMS? Do you have a scope photo of charge current?