MP2625

– SINGLE CELL SWITCHING CHARGER WITH POWER PATH CONTROL

MP2625 Rev. 1.12

www.MonolithicPower.com

17

10/29/2013

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© 2013 MPS. All Rights Reserved.

Enable Ideal Diode Mode

Disable Ideal Diode Mode

Figure 3

— Ideal Diode Mode Enable/Disable

In summary, the terminal battery voltage is 4.2V

(typical) when SYSFB is float or programmed

resistor divider- programmed lower than 4.2V.

Automatic Recharge

Once the battery charge cycle is completed, the

MP2625 turns off indicating the battery full status.

During this process, the battery power may be

consumed by the system load or self discharge.

If the input power is always on, to ensure the

battery not to be exhausted, the new charge

cycle will automatically begin when the battery

voltage falls below the auto-recharge threshold

float, and 50mV lower if the SYSFB is connected

to a resistor divider. The timer will re-start when

the auto-recharge cycle begins.

During the charge off state when the battery is

fully charged, if the input power is recycled, or

the EN signal is refreshed, the charge cycle will

re-start and the timer will refresh even if the

battery voltage is above the auto-recharge

threshold.

Charge Current Setting

The

charge

current

of

the

MP2625

is

programmed using a single resistor from ISET

pin to ground. The program resistor and charge

current

are

calculated

using

the

following

equations:

CHG

SET

1800

I

1.15

(mA)

R

(k )





At either constant current mode or constant

voltage mode, the voltage at the ISET pin is

proportional

to

the

actual

charge

current

can be calculated by monitoring the ISET pin

voltage with the following formula:

CHG

ISET

BAT T

I

×

1.15

V

=

I

Additionally, the actual battery charge current

may be lower than the programmed current due

to limited input power available and prioritization

of the system load.

internally at 10% of the programmed charge

limit which can not be exceeded.

Logic Control

The MP2625 has two separate enable control

pins.

EN

_____

is a logic control pin that controls the

operation of the whole IC. When EN

_____

is low, the

IC is enabled and the PWM converter output

powers the system and the charger. When EN

_____

is

high, both the PWM converter and the charger

are disabled. The BATT to SYS switch turns fully

on to connect the battery to power the system.

The ISET pin can be also used to control the

operation of the charger. Setting ISET pin floating

will disable the charger function while the output

of PWM converter will continue supply power to

system. On the other hand, a resistor from ISET

to AGND will enable the charging at the

programmed charge current.

The logic control of the ISET pin of the MP2625

can be realized as Figure 4. In this way, the user

can choose logic low to be “on” signal or logic

high to be

”off” signal with a N-MOSFET.

ISET

OFF ON

Figure 4

— ISET Logic Control