Philips Semiconductors

Product data

NE57607

Two-cell Lithium-ion battery protection with

overcurrent, over- and under-voltage protection

2001 Oct 03

7

APPLICATION INFORMATION

SL01567

87

NE57607

5

4

3

21

+

6

–

CHARGER

OR

LOAD

Li-ION CELL

Li-ION CELL

1 M

Ω

10 k

Ω

10 k

Ω

47 k

Ω

0.1

µF

0.1

µF

0.1

µF

1 k

Ω

330

Ω

330

Ω

Figure 6. Typical application circuit

The NE57607 drives the series N-Channel MOSFETs to states

determined by each of the cell’s voltage and the battery pack load

current. During normal periods of operation, both the discharge and

charge MOSFETs are in the ON state, thus allowing bidirectional

current flow.

If the battery pack is being charged, and either of the cell’s voltage

exceeds the overvoltage threshold, then the charge MOSFET is

turned OFF (FET towards the pack’s external terminal). The cell’s

voltage must fall lower than the overvoltage hysteresis voltage

If the battery pack is being discharged and the undervoltage

turned OFF. It will not run back ON until a charger is applied to the

pack’s external terminals AND the cell’s voltage rises above the

When the battery pack is being discharged, the load current causes

the voltage across the discharge MOSFET to increase past the

is turned OFF after a fixed 7–18 ms delay. If short-circuit is placed

across the pack’s terminals, then the discharge MOSFET is turned

OFF after a 100–300

µs time delay to avoid damaging the MOSFETs.

FET STATUS FOR NORMAL AND ABNORMAL

CONDITIONS

Operating Mode and Charging

Condition

Charge

FET (CF)

Discharge

FET (DF)

Normal (charging or discharging)

ON

ON

Overcharge (charging)

OFF

ON

Overcharge (discharging)

ON

ON

Overdischarge (discharging)

OFF

OFF

Overdischarge (charging)

ON

ON

Overcurrent (charging or discharging)

OFF

OFF

Normal mode:

Overdischarge detection voltage < battery voltage <overcharge

detection voltage

Discharge current < overcurrent detection level

Overcharge mode:

Battery voltage > overcharge detection voltage

Overdischarge mode:

Overdischarge detection voltage > battery voltage

Overcurrent mode:

Discharge current > overcurrent detection level

voltage between VM and GND = discharge current

× FET ON

resistance (discharge or charge FET)