Cell Voltage (mV)
Error
(mV)
2000 2250 2500 2750 3000 3250 3500 3750 4000 4250
-1
0
1
2
3
4
D001
Cell1
Cell2
Cell3
Cell4
Cell5
Cell6
Cell7
Cell8
Cell9
Cell10
Cell11
Cell12
Cell13
Cell14
Cell15
Cell16
Figure 3-3. Cell Voltage Accuracy
Pack Current Accuracy
This design uses two parallel 2-mΩ, 2-W, 50-PPM shunt resisters to measure pack current. Board offset was
calibrated using the guidance of the Calibration section of the BQ76952 Evaluation Module User's Guide. Then
Current Gain was calibrated with 5-A discharging current and also followed the guidance of the Calibration
section of the BQ76952 Evaluation Module User's Guide. It is good to write the Board Offset and Current Gain
values with OTP to BQ76952, otherwise the MCU has to store such data and write to BQ76952 every time it
wakes up from shutdown mode. Figure 3-4 shows the pack current accuracy data under room temperature. The
maximum current error is below ±10 mA when discharging current is below 2 A and ±0.5% when discharging
current is above 2 A.
Current (mA)
Error
(mA)
0 3000 6000 9000 12000 15000 18000 21000 24000 27000
-30
-25
-20
-15
-10
-5
0
5
10
D002
Figure 3-4. Pack Current Accuracy
Auxiliary Power and System Current Consumption
Thanks to the auxiliary power strategy, this design has very low current consumption, especially when in standby
mode and ship mode. System-level current consumption contains 3 parts: (1) DC/DC current, (2) BQ76952
current (current into BQ76952 BAT PIN), (3) LDO current (current into BQ76952 REGIN PIN). This current could
be measured from the voltage across (1) R115, (2) R61, and (3) R94. Table 3-5 shows the test results of current
consumption.
Table 3-5. Current Consumption in Standby and Ship Modes
R115 (100
Ω)
R61 (100
Ω)
R94 (249
Ω)
Total
Current
(µA)
Standby Mode Voltage (mV) 0.66 2.02 11.45 72.8
Current (µA) 6.6 20.2 46
Ship Mode Voltage (mV) 0.66 0 0 6.6
Current (µA) 6.6 0 0
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10s–16s Battery Pack Reference Design With Accurate Cell Measurement and
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