MP2633 – 1.5A SINGLE CELL SWITCH MODE BATTERY CHARGER

MP2633 Rev. 1.05

www.MonolithicPower.com

27

4/19/2013

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2013 MPS. All Rights Reserved.

APPLICATION INFORMATION

COMPONENT SELECTION

Setting the Charge Current in Charge Mode

In charge mode, both the external sense resistor,

pin to set the charge current (ICHG) of the

MP2633 (see the Typical Application circuit).

)

A

(

I

)

m

(

1

RS

)

mV

(

V

CHG

IREF

×

Ω

=

(7)

)

mV

(

40

)

k

(

R

)

k

(

70

)

mV

(

V

ISET

IREF

×

Ω

Ω

=

(

)

mV

(

40

)

mV

(

V

)

k

(

70

)

k

(

R

IREF

ISET

×

Ω

=

Ω

(

Setting the Input Current Limiting in Charge

Mode

In charge mode, connect a resistor from the ILIM

pin to AGND to program the input current limit.

The relationship between the input current limit

and setting resistor is:

)

k

(

)

A

(

I

5

.

40

R

LIM

_

IN

ILIM

Ω

=

(10)

in the range of 0A to 2A.

Setting the Input Voltage Range for Different

Operation Modes

A resistive voltage divider from the input

voltage

to

PWIN

pin

determines

the

operating mode of MP2633.

)

V

(

6

R

4

R

6

R

V

V

IN

PWIN

+

×

=

(

If the voltage on PWIN is between 0.8V and

1.15V, the MP2633 works in the charge mode.

While the voltage on the PWIN pin is not in the

range of 0.8V to 1.15V and VIN > 2V, the

MP2633 works in the boost mode (see MPS. All

Rights Reserved.

).

For a wide operating range, use a maximum

input voltage of 6V as the upper threshold for a

voltage ratio of:

6

R

4

R

6

R

6

15

.

1

V

V

IN

PWIN

+

=

=

(12)

With the given R6, R4 is then:

6

R

V

V

V

4

R

PWIN

PWIN

IN

×

−

=

(

For a typical application, start with R6=5.1kΩ, R4

is 21.5kΩ.

Setting the Input Voltage Regulation in

Charge Mode

In charge mode, connect a resistor divider from the

VIN pin to AGND with tapped to REG pin to program

the input voltage regulation.

5

R

5

R

3

R

V

V

REG

R

_

IN

+

×

=

(14)

With the given R5, R3 is:

5

R

V

V

V

3

R

REG

RGE

R

_

IN

×

−

=

(15)

For a preset input voltage regulation value, say

4.75V, start with R5=5.1kΩ, R3 is 15kΩ.

NTC Function in Charge Mode

Figure 12 shows that an internal resistor divider

thermistor, select an appropriate RT1 and RT2 to

set the NTC window.

%

65

TL

//R

R

R

//R

R

V

V

NTC_Cold

T2

T1

NTC_Cold

T2

SYS

TL

=

=

+

=

(16)