SLUAAF8 October   2021 BQ24707 , BQ24707A , BQ24725A , BQ24735 , BQ24770 , BQ24780S , BQ24800 , BQ25700A , BQ25708 , BQ25710 , BQ25720 , BQ25730 , BQ28Z610-R1 , BQ4050 , BQ40Z50 , BQ40Z50-R1 , BQ40Z50-R2 , BQ40Z80

 

  1.   Trademarks
  2. 1Introduction
  3. 2Smart Battery Setup
    1. 2.1 Gauge Setup
      1. 2.1.1 I2C System Differences
    2. 2.2 Charger Setup
  4. 3Communication Protocol
  5. 4Data Collected
  6. 5Summary
  7.   A Appendix
    1.     A.1 General Setup
    2.     A.2 Gauge Setup - SMBus
    3.     A.3 Gauge Setup - I2C
    4.     A.4 Charger Setup
    5.     A.5 Charge Voltage Example
    6.     A.6 Charge Current Example
  8.   B References

A.6 Charge Current Example

An example of the charging current communication with the packet structure follows:

0x12 (write) 0x14 0xC4 0x09 0xC4

Current: 0x09C4 = 0000 1001 1100 0100

Comparing the register bit definitions from the Charger Setup section, the charge current can be calculated:

2048 + 256 + 128 + 64 + (4) = 2500 mA

The desired programmed charge current is 2500 mA, but 4 mA does not exist in the bq25710 register definitions, it is reserved. Reserved bits cannot be written to on the charger, so whatever the gauge writes the charger will not update the reserved bits.

GUID-20210730-SS0I-FQF8-LGRJ-3FDCPFVXFD8V-low.pngFigure 6-6 Current Write From the Gauge to the Charger in Broadcast Mode