BQ2970 Datasheet, PDF (15/31 Pages) Texas Instruments – Cost-Effective Voltage and Current Protection Integrated Circuit

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8.3 Test Circuit Diagrams
1 NC
2 COUT
V V COUT
3 DOUT
V V DOUT
V- 6
BAT 5
VSS 4
220Ω
V1
bq2970, bq2971, bq2972, bq2973
SLUSBU9C – MARCH 2014 – REVISED MARCH 2016
1 NC
2 COUT
V V COUT
3 DOUT
V V DOUT
V- 6
IBAT
V2
BAT 5
A
VSS 4
V1
Figure 20. Test Circuit 1
1 NC
2 COUT
IV-
V- 6
A
IBAT
V2
BAT 5
A
3 DOUT
VSS 4
V1
Figure 21. Test Circuit 2
1 NC
ICOUT
A
2 COUT
IDOUT
V3
A
3 DOUT
V4
V- 6
V2
BAT 5
VSS 4
V1
Figure 22. Test Circuit 3
1 NC
Oscilloscope
2 COUT
Oscilloscope
3 DOUT
V- 6
BAT 5
VSS 4
Figure 23. Test Circuit 4
V2
V1
Figure 24. Test Circuit 5
9 Detailed Description
9.1 Overview
This bq2970 device is a primary protector for a single-cell Li-Ion/Li-Polymer battery pack. The device uses a
minimum number of external components to protect for overcurrent conditions due to high discharge/charge
currents in the application. In addition, it monitors and helps to protect against battery pack overcharging or
depletion of energy in the pack. The bq2970 device is capable of having an input voltage of 8 V from a charging
adapter and can tolerate a voltage of BAT – 25 V across the two input pins. In the condition when a fault is
triggered, there are timer delays before the appropriate action is taken to turn OFF either the CHG or DSG FETs.
There is also a timer delay for the recovery period once the threshold for recovery condition is satisfied. These
parameters are fixed once they are programmed. There is also a feature called zero voltage charging that
enables depleted cells to be charged to a acceptable level before the battery pack can be used for normal
operation. Zero voltage charging is allowed if the charger voltage is above 1.7 V. For Factory Programmable
Options, see Table 1.
Table 1. Factory Programmable Options
V_OVP
V_UVP
V_OCD
V_OCC
V_SCC
t_OVPD
t_UVPD
t_OCDD
PARAMETER
Overcharge detection voltage
Over-discharge detection voltage
Discharging overcurrent detection voltage
Charging overcurrent detection voltage
Short Circuit detection voltage
Overcharge detection delay time
Over-discharge detection delay time
Discharging overcurrent detection delay time
FACTORY DEVICE CONFIGURATION
3.85 V to 4.60 V in 50-mV steps
2.00 V to 2.80 V in 50-mV steps
90 mV to 200 mV in 5-mV steps
–45 mV to –155 mV in 5-mV steps
300 mV, 400 mV, 500 mV, 600 mV
0.25s, 1.00s, 1.25s, 4.50 s
20 ms, 96 ms, 125 ms, 144 ms
8 ms, 16 ms, 20 ms, 48 ms
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