SS4036G datasheet(6/9 Pages) SSC

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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

LED

VDD

GND

TEMP

CCTL

LED

ISENSE

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

VDD. The SS4036G monitors the charge current by

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

sensor. A 103AT and a voltage divider (resistor RA

and RB) are recommended.

The resistor values for RA and RB are calculated

using the following equations:

Where,

VDD is 5V

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,

then RA = 6.8kΩ , RB= 20kΩ .

The temperature detection can be disabled by

connecting the Temp pin (2) to VDD.

1.615 x Rc x Rh

Rc - Rh

RA =

5 x Rc x Rh

2Rc - 7 Rh

RB =

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