I am struggling to get the BQ25504 to provide a regulated 5.1V on VSTOR when I have <10kOhm resistor to GND on this pin. On the input to the BQ25504 I have a 3.0V Zener diode, 10uF cap to GND and a nonlinear load resistor that varies between 80kOhms (0.1V)-500kOhms (3V).
I am using the following values from the schematic on the datasheet (Figure 14 - Typical Solar Application Circuit).
| U2 | BQ25504 |
| L1 | 22uH, 0805, 100mA |
| D1 | 3.0V Zener Diode |
| CBYP | 0.01uF, 0603, 10V |
| CSTOR | 4.7uF, 0805, 10V |
| CREF | 0.01uF, 0603, 10V |
| ROC1 | 10M |
| ROC2 | 10M |
| ROV1 | 3.6MHOHM, 0402 |
| ROV2 | 6.49MOHM, 0402 |
| RUV1 | 3.0MOHM, 0402 |
| RUV2 | 6.98MOHM, 0402 |
| ROK1 | 2.8MOHM, 0402 |
| ROK2 | 6.98MOHM, 0402 |
| ROK3 | 220K, 0402 |
I have an 820uF electrolytic cap on VBAT.
When I have an open circuit on VSTOR the circuit starts up nicely. When I have a 10kOhm resistor on VSTOR to GND then I can't get the circuit to start up. Any recommendations would be welcome.
