MP2618 – 2A, 24V INPUT, 600kHz 2-3CELL SWITCHING LI-ION BATTERY CHARGER

MP2618 Rev. 0.92

www.MonolithicPower.com

6

7/14/2010

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PIN FUNCTIONS

Pin #

Name

Description

1,10,12,22

NC

No Connection

2

NTC

Thermistor Input. Connect a resistor from this pin to the pin VREF33 and the Thermistor

from this pin to ground.

3

ACOK

Valid Input Supply Indicator. A logic LOW on this pin indicates the presence of a valid

input supply.

4

CHGOK

Charging status Indicator. A logic LOW indicates charging operation. The pin will become

an open drain once the charging is stopped.

5

VREF33

Internal linear regulator 3.3V reference output. Bypass to GND with a 1µF ceramic

capacitor.

6

VREF25 Internal linear regulator 2.5V reference output.

7

EN

On/Off Control Input.

8

SHDN

Shutdown control of current sense amplifier. Connect this pin to

9

RG1

Gain Resistor of current sense amplifier.

11, 21

GND,

Exposed

Pad

Ground. This pin is the voltage reference for the regulated output voltage. For this reason

care must be taken in its layout. This node should be placed outside of the D1 to C1

ground path to prevent switching current spikes from inducing voltage noise into the part.

Connect exposed pad to ground plane for optional thermal performance.

13

OUT1

Output for Driving Resistor Load.

14

RG2

Gain Resistor of current sense amplifier.

15

VCC

Power Input of current sense amplifier.

16

COMPV VLOOP Compensation. Decouple this pin with a capacitor and a resistor.

17

CELLS

Command Input for the Number of Li-Ion Cells. Make this pin float for 3-cell operation or

connect this pin to ground for 2-cell operation.

18

COMPI ILOOP Compensation. Decouple this pin with a capacitor and a resistor.

19

BATT

Positive Battery Terminal.

20

CSP

Battery Current Sense Positive Input. Connect a resistor RS1 between CSP and BATT.

23

TMR

Set time constant. 0.1uA charge and discharge the external cap. Connect TMR pin to

GND to disable the internal timer.

24

BST

Bootstrap. This capacitor is needed to drive the power switch’s gate above the supply

voltage. It is connected between SW and BST pins to form a floating supply across the

power switch driver.

25, 26

SW

Switch Output.

27

PIN

Power Supply Voltage. The MP2618 operates from a +5.5V to +24V unregulated input.

C1 is needed to prevent large voltage spikes from appearing at the input.

28

AIN

Controller Supply Voltage.