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SS4036G

1/09/2006 Rev.3.01

VOLTAGE, CURRENT AND TEMPERATURE SENSING

10k

Ω

CELL2

CELL1

6.8k

Ω

103AT

THERMISTER

R13 51k

Ω

51k

Ω

R14

51k

Ω

100m

Ω

VDD

20k

Ω

3k

Ω

LED

VDD

1

GND

8

TEMP

2

V2

7

CCTL

3

V1

6

LED

4

ISENSE

5

SS4036G

Figure 3. Cell voltage, current sense and temperature sensor

Figure 3 shows the cell voltage sense, current sense

sense and temperature detecting circuit. The pack

pack voltage is divided by 2 (by using two equal

resistors, R13 and R14). This guarantees that the

the voltage on the V2 input pin (7) will not exceed

measuring at the Isense input pin (5) the voltage drop

across a sense resistor, connected between VSS

(battery negative) and GND (Charger ground). The

value of this resistor should be between 50m

Ω and

150m

Ω .

To detect the temperature, a negative-temperature-

coefficient thermistor is used as a sensor. A 103AT

using the following equations:

Where,

Rc is the cold temperature resistance

Rh is the hot temperature resistance

RA, RB are in k

Ω .

Example :

For thermistor 103AT, the hot temperature

temperature is 55°C and the cold temperature is 5°C,

The temperature detection can be disabled by

1.615 x Rc x Rh

Rc - Rh

RA =

5 x Rc x Rh

2Rc - 7 Rh

RB =