MAX712CSE(2002) データシートの表示（PDF） - Maxim Integrated

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MAX712CSE
(Rev.:2002)

NiCd/NiMH Battery Fast-Charge Controllers

Maxim Integrated 

NiCd/NiMH Battery

Fast-Charge Controllers

Linear-Mode, High Series Cell Count

The absolute maximum voltage rating for the BATT+ pin

is higher when the MAX712/MAX713 are powered on. If

more than 11 cells are used in the battery, the BATT+

input voltage must be limited by external circuitry when

DC IN is not applied (Figure 15).

Efficiency During Discharge

The current-sense resistor, RSENSE, causes a small

efficiency loss during battery use. The efficiency loss is

significant only if RSENSE is much greater than the

battery stack’s internal resistance. The circuit in Figure

16 can be used to shunt the sense resistor whenever

power is removed from the charger.

Status Outputs

Figure 17 shows a circuit that can be used to indicate

charger status with logic levels. Figure 18 shows a

circuit that can be used to drive LEDs for power and

charger status.

DC IN

R2

150Ω

Q1

D1

33kΩ

500Ω

TO

BATTERY

POSITIVE

TERMINAL

Q2

MAX712

MAX713

DRV

BATT+

Figure 15. Cascoding to Accommodate High Cell Counts for

Linear-Mode Circuits

V+

MAX712

MAX713

10kΩ

FASTCHG

OV = NO POWER

5V = POWER

VCC

OV = FAST

VCC = TRICKLE OR

NO POWER

Figure 17. Logic-Level Status Outputs

D1

MAX712

MAX713

100kΩ

V+

100kΩ

*

GND

DC IN

>4 CELLS

RSENSE

*LOW RON

LOGIC LEVEL

N-CHANNEL

POWER

MOSFET

V+

MAX712

MAX713

FASTCHG

R1

CHARGE POWER

470ΩMIN

FAST CHARGE

Figure 16. Shunting RSENSE for Efficiency Improvement

Figure 18. LED Connection for Status Outputs

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