MP26053 datasheet(7/11 Pages) MPS

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MP26053 – 28V, 1A LINEAR BATTERY CHARGER WITH TRICKLE CHARGE AND TIMER

MP26053 Rev. 0.9

www.MonolithicPower.com

8/25/2008

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

OPERATION

Input Voltage Range

The MP26053 has built-in input voltage surge

protection as high as +28V. The charger IC will

be automatically disabled when the input

voltage is lower than 3.0V or higher than 7.0V.

The open-drain pin ACOK is used to indicate

input

power

good

condition

(i.e.

3.0V<VIN<7.0V). If the input voltage is lower

than the battery voltage, the IC is also disabled

to prevent the battery from draining.

Charge Cycle (Mode Change: Trickle -> CC->

CV)

Figure 2 shows the typical charging profile for

the MP26053. For a fully depleted battery with a

terminal voltage lower than 2.6V, the MP26053

will

start

with

the

trickle

charge

(preconditioning) at 10% of the full charge

current based on the value of RCHG. If the

charger stays in trickle mode longer than 32768

cycles,

CHG

becomes

high

impedance,

indicating a battery fault. After the battery

voltage reaches 2.6V, the charger begins

charging using the programmed charge current

(ICHG).This is referred to as Constant Current

(CC) mode. Once the battery voltage reaches

4.2V, the charger will operate in the constant

voltage (CV) mode until the battery is fully

charged. The charge current drops during CV

mode, and the battery full indication is set when

the charge current is reduced to 10% of the

programmed constant current value (ICHG). The

charge process is then terminated. Recharge

will start after the battery voltage is reduced to

4.0V. After 262144 cycles of continuous

charging, if the battery still has not reached

10% of the ICHG condition, the on-chip timer will

terminate the charger to prevent charging the

dead battery excessively and the fault condition

will be flagged by flashing the CHG LED.

Charge Termination

The charge current will gradually decrease in

CV mode as the battery approaches full. The

battery full threshold is internally programmed

to be 10% of the ICHG. When the charge current

reaches this threshold, the charger IC will be

automatically turned off.

2.6V

4.2V

VBATT

10% of ICHG

Trickle

Charging

Complete

Charging

ICHG

IBATT

Figure 2—MP26053 Typical Charging Profile

Automatic Recharge

When VBATT drops to 4.0V, the charger will

automatically restart the charge cycle until the

10% ICHG condition is met again. When the input

adapter is unplugged, or the charger is disabled

and/or terminated, the leakage current from the

battery to the MP26053 is less than 1uA.

Programming of Charge Current and Battery

Full Current

The charge current (ICHG) is set by a resistor

(RCHG) connected from the ISET pin to GND.

The relationship between the charge current

and the programming resistance is established

by the following table and graph.

Table 1—RCHG and ICHG Relationship

RCHG (kΩ)

ICHG (mA)

1.65

1000

1.82

900

2.05

800

2.32

700

2.74

600

3.3

500

4.12

400

5.6

300

8.45

200

100

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