MP2625B – SINGLE CELL SWITCHING CHARGER WITH POWER PATH CONTROL

MP2625B Rev. 1.01

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18

1/15/2018

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battery voltage is above the auto-recharge

threshold.

Charge Current Setting

The

charge

current

of

the

MP2625B

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

I1.15

(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

BATT

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.

Ideal Diode Mode

If the system current requirement increases over

the preset limit of the PWM converter, the

additional current will be drawn from the battery

via the BATT-to-SYS switch. To avoid very large

currents being drawn from the battery which

might affect the reliability of the device, the

MP2625B controls the charge switch to work at

mode, and the charge cycle softly restarts.

Enable Ideal Diode Mode

Disable Ideal Diode Mode

Figure 3: Ideal Diode Mode Enable/Disable

Logic Control

The MP2625B 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 MP2625B

can be realized as Figure 3. In this way, the user

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

high to be ”on” signal with a N-MOSFET.

ISET

OFF ON

Figure 4: ISET Logic Control

Input Power Status Indication (ACOK

__________

)

An internal under voltage lockout circuit monitors

the input voltage and keeps the IC in off state

until the input rises over the rising threshold

(3.8V). When the input voltage decreases below

threshold (3.5V), the IC will turn off, and the

system load will be powered by the battery