MP2605 datasheet(10/13 Pages) MPS

10 / 13 page

MP2605 – 28V, 1A LINEAR BATTERY CHARGER WITH TRICKLE CHARGE AND TIMER

MP2605 Rev. 0.94

www.MonolithicPower.com

1/25/2010

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

Charge Current vs.

1/RCHG

1000

900

800

700

600

500

400

300

200

0.2

0.1

0.3 0.4

0.6 0.7

0.5

Figure 3—Charge Current vs. 1/RCHG

Resistance

The recommended resistance for programming

the charge current is 2.3kΩ<RCHG<11kΩ. The

open-drain pin CHG is used to indicate

charging status. When the battery full condition

is met or any other condition prevents the

charger from charging, CHG will become a

floating pin.

Timer Operation

The TMR pin is used to set the internal

oscillator frequency,

OSC

TMR

F11Hz

=×

. The

on-chip timer will start to count down after initial

power-up or every time it is enabled. This timer

will limit the max trickle-charge time to 32768

internal oscillating cycles. If the charger stays in

trickle mode for longer than 32768 cycles, it will

be terminated and a fault will be set by floating

CHG

pin. After fault reporting, the charger can

be re-initiated only by recycling the power

supply or SHDN signal. If the charger

successfully goes through trickle charge within

the allowed time limit, it will start CC charging

and then CV charging. If the total charge time

exceeds 262144 cycles and the battery full has

not been qualified, the charger will be

terminated and a fault will also be set by

flashing CHG pin at the rate of half the internal

oscillation frequency. This function prevents

charging a dead battery for prolonged duration.

The timer function can be disabled by shorting

TMR to ground.

Negative Thermal Coefficient (NTC) Thermistor

The MP2605 has a built-in NTC resistance

window comparator. If configured as the typical

application circuit as indicated in Figure 1, the

MP2605 will cease charging if RNTC<32.3kΩ or

RNTC>376.6kΩ. This represents a valid charging

temperature range of 0°C to 50°C for the

TH11-4H104F NTC resistor.

Thermal Protection

The MP2605 has proprietary thermal protection

to prevent the IC from overheating. When in

thermal protection mode, the average charge

current will be reduced to prevent the IC from

overheating. Operating in thermal protection

mode will slow down the charging process.

Lowering the input voltage and enhancing

thermal dissipation to the environment can

effectively prevent the IC from going into

thermal protection mode.

MP2605 Datasheet(PDF) 10 Page - Monolithic Power Systems

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