Philips Semiconductors

Product data

NE57610

Li-ion battery charger control

with adjustable thresholds

2002 Nov 05

10

NE57610 OPERATION

The typical application schematic is given in Figure 17. Because in

a multiple-cell battery pack, the battery charger cannot access the

connection(s) between the cells within a battery pack, the following

discussion is based upon the calculated value of each cell’s voltage

Start of charging

The start of the charging process is only permitted when all of the

following conditions are met:

is sufficient input voltage.

ov)

operating range.

The charging behavior depends on the voltage of the battery. If the

initial cell voltage is:

into the battery pack and the undervoltage charge timer is set. If the

period of time, the pack is assumed to be damaged and the

charging process is terminated. The charger can be restarted by

bringing RESET momentarily high, or by turning-OFF and then ON

the input voltage.

battery pack. This continues until the cell voltage reaches 2.9 V. If

the pre-charge timer, times out prior to the cell reaching 2.9 V, the

pre-charge is terminated. The charger can be restarted by bringing

RESET momentarily high, or by turning-OFF and then ON the input

voltage.

placed into the battery pack until the cell reaches a full-charge

full-charge level within the period of the charge timer, the charge is

terminated.

completely cut off. If the battery pack is allowed to remain on the

charger for an extended period, and if the pack voltage falls to 3.9 V

per cell due to self-discharge, charging begins again at the full rate

long as the battery is in the charger.

Overriding conditions

If, under any of the above conditions, the following conditions are

encountered, the charging process will be immediately terminated.

with higher temperatures)

A State diagram of the various modes of the charger can be seen in

Figure 18.

SL01863

ON/OFF RESET

GND

PGND

21

6

7

TMP

12

5

TP2

4

TP1

3

BAT2

14

BAT1

13

DRV

17

BCP51

18

15

CS

PBYR

240CT

TP2

TP1

THERM

V–

V+

BATTERY PACK

CELL 2

CDLL 1

OSC1

OSC2

24

23

GRN

21

RED

22

GRN

RED

150

Ω

10

µF

NE57610

Figure 17. Typical application circuit (2-cell).