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One Series X parallel Pack Protect,
Charge Management, Fuel Gauge PCA
FEATURES
Battery Pack Protection:
- Battery Overcharge Protection
- Battery Overdischarge Protection
- Discharge Overcurrent Protection
- Charge Overcurrent Protection
- Load short-circuit Protection
- Inhibit 0V charging condition
Charge Management:
- Charge Temperature Monitoring
- 3 phase charge: Conditioning,
Constant Current, Constant Voltage
- 3-States Charge LED indication
- Enter low power mode when charger removed
Fuel Gauge:
- Accurate Battery Fuel Gauging
- Cell Temperature monitoring
- Memory Space for manufacturing information
- Auto-compensate for battery aging, selfdischarge
- Industry standard I2C Protocol |
DESCRIPTION
This PCA module provides three highly desired functions: Battery Pack Protection, Fuel Gauge, and Charge Management; all in one small form-factor 0.65 inch x 2.5 inch PCB, designed specifically for one series, X parallel battery pack configuration. The circuit is designed in three functional blocks.
Pack Protection block provides necessary protection against cell Overcharge/ Overdischarge, abnormal
charge/discharge current, and load short-circuit.
The integrated Charge Management enables enduser
to utilize a simple DC power input to charge the
battery pack. In other words, no special Li-Ion
charger is necessary. The charging goes through a 3
staged charge profile and terminates charge at pre-set
taper current. Charging is also inhibited outside a preset temperature window.
Finally, the Fuel Gauge provides many critical
information of the pack condition, such as remaining
capacity, pack voltage, and pack temperature. Enduser
can develop host application to retrieve such
information through standard I2C protocol. |
Block Diagram
SPECIFICATION (Customized spec. is possible under special circumstances,
please contact S.W.E for information)
| Pack 0V Charge |
Inhibited
|
| Operating Temperature |
-40 ºC ~85 ºC
Charge is limited to -5 ºC ~ 45 ºC
|
| Current Consumption |
Active Mode: 4.2mA Max.
Sleep Mode: 66 uA Max.
|
| Overcharge Voltage |
4.28 V
|
| Overcharge Release Voltage |
4.13 V
|
| Overdischarge Voltage |
2.80 V
|
| Overdischarge Release Voltage |
3.10 V
|
| Dicharge Overcurrent Voltage |
0.15 V
|
| Charge Overcurrent Voltage |
0.1 V
|
| Discharge Overcurrent Threshold |
Refer to Table A
|
| Charge Overcurrent Threshold |
Refer to Table A |
Table A
Discharge
Overcurrent
(A) |
Power
Dissipation (mW) |
Max. Sense
Error (%)* |
Charge
Overcurrent |
2A |
240 |
1% |
1A |
3A |
357 |
1% |
1A |
4A |
472 |
2% |
2A |
5A |
550 |
2% |
2A |
6A |
556 |
3% |
2A |
7A |
588 |
4% |
2A |
*Assumed min. sense current is 20mA
| Recommended Charger Voltage* |
5 V (±0.1 V)
|
| Conditioning Current |
1/10 of charge current
|
| Voltage Regulation |
4.1 V
|
| Max Power Dissipation (Charge) |
Refer to Table B
|
| Max. Charge Current* |
Refer to Table B
|
| Charge Termination Current |
Refer to Table B
|
| Communication Protocol |
I2C
|
| User Memory Space |
96 Bytes, Non-volatile
|
Table B
Charge
Current (A)* |
Termination
Current (mA) |
Max. Power
Dissipation (W) |
0.5 |
70 |
0.5 |
1 |
140 |
2 |
2 |
280 |
8 |
*Note: Due to power dissipation concern, charge current over 2 A
or Input Voltage over 5 V is strongly discouraged.
OPERATION DESCRIPTION
Pack Protect
| Normal State: |
When battery pack voltage (Vpack) is between 2.80 V and 4.28 V, both CHG/DSG FETs are turned on. Pack can charge and discharge normally.
|
| Overcharge State:* |
When Vpack > 4.28 V, CHG FET is off and no further charge is allowed. The Overcharge status is released when Vpack drops below 4.13 V, the CHG FET then turns back on.
|
| Overdischarge State: |
When Vpack < 2.8 V, DSG FET is off, and no further discharge is allowed. The Overdischarge status is released when Vpack goes above 3.10 V, the DSG FET is then turned back on.
|
| Discharge Overcurrent: |
Refer to Table A. When discharge current goes above current rating, the DSG FET is turned off to prohibit further discharge. This status is released if discharge current falls below the rating, or by removing the load.
|
| Charge Overcurrent:* |
Refer to Table A. When charge current goes above current rating, CHG FET is turned off to prohibit further charging. This status is released if charge current falls below
the rating, or by removing the charger.
|
*Note: Both Overcharge or Charge Overcurrent should not occur since charge
management control is integrated in the design.
Charge Management
With 5 V input present (LOAD disconnected), charge first starts in Constant Current mode at desired rate
according to Table B. Once it reaches 4.1 V, it’s switched to Constant Voltage mode until Termination current is
reached. Pack temperature is continuously being monitored before and during the charge. The control will prohibit
charge if pack temperature falls outside of the pre-set window -5 ºC ~ 45 ºC. If the pack voltage is under 3 V when
charging started, the charging will start with a conditioning current, which is about 1/10 of the normal constant
current charge phase. The on-board LED provides 3 charge status as described in Table C. The PCA module also
provides one charge-status pin out, which has High, Low, or Hi-Z output for optional off-board usage, for example,
to interface with a host processor.
Table C
Charge Status |
On-board LED Indication |
No Charge Power |
Off |
Charging |
RED |
Charge Completed |
GREEN |
Temperature Fault |
Amber/Yellow |
Fuel Gauge
The end-user can interrogate the battery pack through standard I2C protocol. One SDA line and One SCL line are
necessary to communicate with the Fuel Gauge chip. Both SDA and SCL line must be “PULL-UP” externally by the
end-user. The PCA module does NOT provide such pull-up method in order to enable gauge going into sleep mode.
Before going to production, a customized golden flash image is created for a specific pack configuration in order to
provide the best accuracy fuel gauging. Then the golden image is programmed to the data flash. The manufacturing
information is also programmed to the 96 bytes memory space if requested by customer. After assembly of the pack,
the pack is RESET, Impedance Track enabled, and finally SEALED. For more technical information about the
Fuel Gauge development, please contact Southwest Electronics Energy Group at 281-240-4000.
Pack Attributes available for end-user
1. Time to empty at discharge rate: Returns the predicted remaining operating time if
discharged at a certain rate.
2. Temperature: Returns the pack temperature in units of 0.1K
3. Voltage: Returns the measured cell-pack voltage in mV
4. Nominal Available Capacity: Returns the uncompensated battery capacity remaining
5. Full Available Capacity: Returns the uncompensated capacity of the battery when
fully charged
6. Remaining Capacity: Returns the compensated battery capacity remaining
7. Full Charge Capacity: Returns the compensated capacity of the battery when
fully charged
8. Average Current: Returns the average current flow through the sense resistor
9. Time to Empty: Returns the predicted remaining battery life at the present
rate of discharge
10. Time to Full: Returns the predicted remaining time until the battery reaches
full charge
11. Standby Current: Returns the measured standby current through the sense resistor
12. Standby Time to Empty: Returns the predicted remaining battery life at the standby
rate of discharge
13. Max Load Current: Returns the maximum load conditions.
14. Max Load Time to Empty: Returns the predicted remaining battery life at the
maximum load discharge rate
15. Available Energy: Returns the predicted charge or energy remaining in the battery
16. Average Power: Returns the average power of the current discharge
17. Time to Empty at Constant Power: Returns the predicted remaining operating time if
the battery is discharged at Average Power
18. Cycle Count: Returns the number of cycles the battery has experienced
19. State of Charge: Returns the predicted remaining battery capacity expressed as a
percentage of Full Charge
Capacity
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