• Resolved

BQ25505: BQ25505 battery charger

Part Number: BQ25505

I have the following circuit: 

The BYP and REF capacitors are ceramic and the remaining capacitors are electrolyte. I have made another circuit for the BQ25570 with these elements with no problem. Also, the BAT2 voltage is 3.7V, not 9V. 

The problem that I have here is that the boost charger does not seem to be working.

1- The VIN_DC is the same as the solar cell Voc. 

2- The VREF_SAMP voltage is zero. I tried other capacitors but made no difference. 

3- The Lboost voltage is the same as the VIN_DC. 

4- The VSTOR voltage is around 150mv lower than VIN_DC. 

5- The VIN_DC voltage does not change every 16 seconds meaning that the MPPT is not taking samples. 

6- Voltage on the C1 capacitor stays at VIN_DC and does not increase. I initially had the OK_HYST and OK_PROG pins connected to mid-point of external resistors but that did not make a difference.  

I was wondering if I could get some help on what might be wrong with this circuit. 

Thanks!