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BQ25155: ADC calculation for VIN, IIN and ICHG

Part Number: BQ25155

Hi Team,

We have ADC reading questions for VIN, IIN and ICHG. Customer use meter to measure actual value to compare with ADC measurement as below. But we don't know why the actual value and ADC reading value cannot match. Could you please provide your suggestion if there is any wrong calculation? Thanks.

  • VBAT voltage – 3.586v
  • VBAT ADC value – 0x9915 = 3587.8mV

BQ25155_RegRead address:0x42 data:0x99

BQ25155_RegRead address:0x43 data:0x15


  • ICHG current – mean 13mA
  • ICHG ADC value – 0x00fb, We cannot understand the formula in page 21 of datasheet.

BQ25155_RegRead address:0x46 data:0x0

BQ25155_RegRead address:0x47 data:0xfb


  • VIN voltage – 4.615v
  • VIN ADC value – 0x6613 = 2392mV, the result is different with actual value.

BQ25155_RegRead address:0x4a data:0x66

BQ25155_RegRead address:0x4b data:0x13


  • IIN current – 380mA
  • IIN ADC value – 0x1559 = 62.5mA, , the result is different with actual value.

BQ25155_RegRead address:0x4e data:0x15

BQ25155_RegRead address:0x4f data:0x59

Best regards,


  • Hi Hardy,

    For a bit more context can you please provide the schematics for the solution as well as the test set up (i.e. measurement instruments, particularly how and where VIN and VBAT are measured)? Additionally, I'm curious what the current draw is from PMID and SYS since the measured IIN is much higher than the measured ICHG.

    ICHG ADC Value is representative of the percentage of ICHG. 0x00FB for ADC_DATA_ICHG indicates that ICHG is at 0.48% of the programmed ICHARGE. 

    Best Regards,

    Juan Ospina