BQ2970 Datasheet, PDF (16/31 Pages) Texas Instruments – Cost-Effective Voltage and Current Protection Integrated Circuit

bq2970, bq2971, bq2972, bq2973
SLUSBU9C – MARCH 2014 – REVISED MARCH 2016
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Overview (continued)
t_OCCD
t_SCCD
Table 1. Factory Programmable Options (continued)
PARAMETER
Charging overcurrent detection delay time
Short Circuit detection delay time
FACTORY DEVICE CONFIGURATION
4 ms, 6 ms, 8 ms, 16 ms
250 µs (fixed)
For available released devices, see the Released Device Configurations table.
9.2 Functional Block Diagram
Oscillator
Counter
Charger
Detection
Circuit
BAT 5
Overcharge
Comparator (OVP)
with Hys
Over-Discharge
Comparator (UVP)
with Hys
Overcharge
Current
Comparator
Over-Discharge
Current Comparator
Logic circuit
Delay
Logic circuit
2 COUT
Short Detect
3 DOUT
VSS 4
R _V–D
BAT
6 V–
I_V–S
9.3 Feature Description
The bq2970 family of devices measures voltage drops across several input pins for monitoring and detection of
the following faults: OCC, OCD, OVP, and UVP. An internal oscillator initiates a timer to the fixed delays
associated with each parameter once the fault is triggered. Once the timer expires due to a fault condition, the
appropriate FET drive output (COUT or DOUT) is activated to turn OFF the external FET. The same method is
applicable for the recovery feature once the system fault is removed and the recovery parameter is satisfied, then
the recovery timer is initiated. If there are no reoccurrences of this fault during this period, the appropriate gate
drive is activated to turn ON the appropriate external FET.
9.4 Device Functional Modes
9.4.1 Normal Operation
This device monitors the voltage of the battery connected between BAT pin and VSS pin and the differential
voltage between V– pin and VSS pin to control charging and discharging. The system is operating in NORMAL
mode when the battery voltage range is between the over-discharge detection threshold (V_UVP) and the
overcharge detection threshold (V_OVP), and the V– pin voltage is within the range for charge overcurrent
threshold (V_OCC) to over-discharge current threshold (V_OCD) when measured with respect to VSS. If these
conditions are satisfied, the device turns ON the drive for COUT and DOUT FET control.
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