Datasheet

Pin Description

MAX712/MAX713

NiCd/NiMH Battery

Fast-Charge Controllers

Maxim Integrated

Compensation input for constant current regulation loopCC11

Negative terminal of batteryBATT-12

GND13

Current sink for driving the external PNP current sourceDRV14

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.

TLO6

Sense input for temperature-dependent voltage from thermistors.TEMP7

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

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 unconnected

(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.THI5

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 unconnected

(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 ΔV fast-charge termination.

PGM0,

PGM1

3, 4

Positive terminal of batteryBATT+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. Connect VLIMIT to VREF for normal operation.

Alternatively, connect VLIMIT to V+ to set the maximum cell voltage to an internally preset 1.65V/cell.

VLIMIT

FUNCTIONNAME

2V reference outputREF16

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