NiCd/NiMH Battery

Fast-Charge Controllers

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5

Pin Description

Compensation input for constant current regulation loop

CC

11

Negative terminal of battery

BATT-

12

System ground. The resistor placed between BATT- and GND monitors the current into the battery.

GND

13

Current sink for driving the external PNP current source

DRV

14

Shunt regulator. The voltage on V+ is regulated to +5V with respect to BATT-, and the shunt current

powers the MAX712/MAX713.

V+

15

Trip point for the under-temperature comparator. If the MAX712/MAX713 power on with the voltage-on

TEMP less than TLO, fast charge is inhibited and will not start until TEMP rises above TLO.

TLO

6

Sense input for temperature-dependent voltage from thermistors.

TEMP

7

Open-drain, fast-charge status output. While the MAX712/MAX713 fast charge the battery, FASTCHG

sinks current. When charge ends and trickle charge begins, FASTCHG stops sinking current.

FASTCHG

8

PGM2 and PGM3 set the maximum time allowed for fast charging. Timeouts from 33 minutes to 264

minutes can be set by connecting to any of V+, REF, or BATT-, or by leaving the pin open (Table 3).

PGM3 also sets the fast-charge to trickle-charge current ratio (Table 5).

PGM2,

PGM3

9, 10

Trip point for the over-temperature comparator. If the voltage-on TEMP rises above THI, fast charge ends.

THI

5

PGM0 and PGM1 set the number of series cells to be charged. The number of cells can be set from

1 to 16 by connecting PGM0 and PGM1 to any of V+, REF, or BATT-, or by leaving the pin open (Table

2). For cell counts greater than 11, see the Linear-Mode, High Series Cell Count section. Charging more

or fewer cells than the number programmed may inhibit

∆V fast-charge termination.

PGM0,

PGM1

3, 4

PIN

Positive terminal of battery

BATT+

2

Sets the maximum cell voltage. The battery terminal voltage (BATT+ - BATT-) will not exceed VLIMIT x

(number of cells). Do not allow VLIMIT to exceed 2.5V. Tie VLIMIT to VREF for normal operation.

VLIMIT

1

FUNCTION

NAME

2V reference output

REF

16