NiCd/NiMH Battery

Fast-Charge Controllers

4

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______________________________________________________________Pin Description

NAME

FUNCTION

1

CCMD

Charge-Enabled Mode Input—initiates fast-charge on a digital signal (see

Detailed Description for operating

conditions).

2

DCMD

Discharge-Enable Mode Input—initiates discharge-before-charge on a digital signal (see

Detailed

Description for operating conditions).

PIN

3

DVEN

Negative Delta Voltage (-

∆V) Enable Input—enables -∆V charge-termination mode. If DVEN is high, the con-

troller uses negative-voltage change detection to terminate charge. If DVEN is low, this mode is disabled.

4, 5

TM1,

TM2

These inputs are used to program the fast-charge and hold-off times, and to enable the top-off charge

mode. The inputs can be high, low, or floating. See Table 4 for details.

9

SNS

Current-Sense Input—connected to the negative battery terminal. TS and BAT are referenced to this pin.

The voltage at SNS is directly proportional to the current through the battery and is used to determine how

and when MOD switches.

8

Ground

7

BAT

Input Voltage of Single Battery Cell. If more than one cell is present, a resistor divider is needed to divide the

voltage down to a single cell voltage.

6

TS

Temperature Sense-Voltage Input from external thermistor. The thermistor temperature coefficient is nega-

tive, so the higher the temperature, the lower the voltage at this pin (See

Detailed Description for conditions

of operation).

14

MOD

Modulation Output. This push/pull output switches to enable or disable charging current. If MOD is high,

current is enabled. If it is low, current is disabled. For a 5V supply, if the voltage at the SNS pin is less than

220mV, MOD is high. If the voltage is above 250mV, MOD is low.

13

CHG

Charge Status Output. This push/pull LED driver indicates charge status (see

Detailed Description).

12

TEMP

Temperature Status Output. This push/pull LED driver indicates that the temperature is outside the accept-

able limits, and fast-charge and top-off are inhibited (see

Maximum Temperature Termination section in

Detailed Description).

11

MCV

Maximum Cell Voltage Input. If the voltage from BAT to SNS exceeds the voltage at MCV, fast or top-off

charging is terminated.

10

TCO

Temperature Cutoff-Voltage Input. If the voltage from TS to SNS is less than the voltage at TCO, a hot ther-

mistor (negative coefficient) is detected and fast or top-off charging is terminated.

16

Power-Supply Voltage Input (+5V nominal). Bypass with a 0.1µF capacitor placed close to the device.

15

DIS

Discharge-Switch Control Output. This push/pull output turns on the FET that discharges the battery.