Other Parts Discussed in Thread: BQ25756
Tool/software:
Using ESP32 to set configuration to BQ25756.
When setting IAC_DPM to 400mA the actual input current (measured at PSU) is 1046mA.IAC_ADC reports 360mA and potential between TP45 and TP46 is 2.7mV.
AMP meter was used to verify that the current reported by PSU is real.(It is)
I've made a table with different settings for IAC_DPM and the measurements for each setting.
In this table we can see that actual current being drawn is 2.5-2.6 times bigger than what was set as a limit.Do you have any idea why that is?
| IAC_DPM (Input current limit) (mA) | IAC_ADC(reported current) (mA) | Power Supply reported current (mA) | Potential between TP45 and TP46 (mV) |
| 400 | 360 | 1046 | 2.7 |
| 450 | 413 | 1172 | 3 |
| 500 | 462 | 1296 | 3.3 |
| 550 | 515 | 1422 | 3.6 |
| 600 | 564 | 1541 | 3.9 |
| 650 | 612 | 1662 | 4.2 |
| 700 | 661 | 1787 | 4.5 |
| 750 | 708 | 1900 | 4.8 |
| 800 | 760 | 2024 | 5.1 |
| 850 | 810 | 2151 | 5.5 |
| 900 | 860 | 2275 | 5.8 |
| 950 | 912 | 2400 | 6.1 |
| 1000 | 960 | 2521 | 6.4 |
| 1050 | 1010 | 2641 | 6.7 |
| 1100 | 1060 | 2762 | 7 |
| 1150 | 1112 | 2891 | 7.4 |
| 1200 | 1162 | 3017 | 7.7 |
| 1250 | 1213 | 3141 | 8 |
| 1300 | 1263 | 3266 | 8.3 |
| 1350 | 1313 | 3389 | 8.7 |
| 1400 | 1363 | 3510 | 9 |
| 1450 | 1410 | 3630 | 9.3 |
| 1500 | 1460 | 3746 | 9.6 |
| 1550 | 1510 | 3867 | 9.9 |
| 1600 | 1561 | 3993 | 10.2 |
| 1650 | 1610 | 4120 | 10.6 |
| 1700 | 1660 | 4244 | 10.9 |
| 1750 | 1713 | 4371 | 11.2 |
| 1800 | 1762 | 4493 | 11.5 |
| 1850 | 1812 | 4610 | 11.8 |
| 1900 | 1860 | 4735 | 12.1 |
| 1950 | 1910 | 4864 | 12.5 |
| 2000 | 1964 | 4986 | 12.8 |
| 2050 | 2014 | 5112 | 13.1 |
As an adition, this is how data is written to register REG0x06_Input_Current_DPM_Limit:
temp = (uint8_t)(current_limit / 50);
reg_data = (uint16_t) temp << 2;
bq25756_write_reg_16bit(0x06, reg_data);
