SM6780AS View Datasheet(PDF) - Nippon Precision Circuits

Part Name

Description

Manufacturer

SM6780AS

Ni-Cd/Ni-MH Battery Charger IC

Nippon Precision Circuits  

SM6780AS

Battery Voltage and Temperature Detection

The battery voltage detector input is BATT. The

charger treats the input voltage as the equivalent

voltage of a single cell. For multiple cells (connected

in series), a high-resistance (> 100kΩ) battery

divider can be used to input the voltage equivalent of

a single cell, as shown in figure 3.

Battery

Ra

BATT pin

Rb

Ra

Rb

=N−1

N:Number of cells

The battery temperature detector input is TEMP. The

input voltage is provided by a negative temperature

coefficient thermistor (NTC thermistor) located in

close proximity to the battery, as shown in figure 4.

The input voltage range is 0.5V to VDD.

Figure 3. BATT connection example

Battery

Rc

TEMP pin

Rd

Figure 4. TEMP connection example

Note that the thermistor temperature characteristics

are non-linear, so a correction resistance Rc should

be used for linearity correction. The temperature rat-

ing of resistances Rc and Rd should be chosen to

match the battery temperature range rating. If the

temperature detection function is not used, the

TEMP input should be fixed at a potential in the

range 0.25VDD to 0.4VDD.

NIPPON PRECISION CIRCUITS—5

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