MP2607 – LI-ION CHARGER WITH POWER PATH MANAGEMENT

MP2607 Rev. 1.02

www.MonolithicPower.com

11

6/19/2013

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© 2013 MPS. All Rights Reserved.

OPERATION

The MP2607 is a highly-integrated single-cell

Li-ion or Li-polymer battery charger with system

power path management function. The full

function charger features trickle charge, high

accuracy constant current (CC) and constant

voltage (CV) regulation, charge termination,

auto recharge, thermal fold-back, built-in timer

and 4-status indicator output. The power path

function allows the input source to power the

system and charge the battery independently. If

there is conflict to meet both system load and

battery

charging

current,

MP2607

will

automatically reduce charging current or even

use battery as supplement to satisfy the system

load. This allows optimal battery charging,

reduces charge/discharge cycle, and best

preserves the battery energy.

Input Selection for Power Path and Charger

MP2607 identifies the input source (IN) based

on the logic level of MODE pin. MODE pulled

high indicates IN is connected with AC adapter,

low indicates IN connected with USB port. In

either case, the input source will supply both

system load and battery charging current. If IN

is not connected to a valid input source, the

battery (BATT) is selected to supply the system

(SYS). The built-in N-channel 50mΩ switch

between BATT and SYS minimizes the

conduction drop and extends the battery life.

The IN of MP2607 can accept voltage as high

as 13V, thus allows the use of low cost high

output ripple adapters.

MODE pin is default “high” with internal pull-up.

Power Path Management

If IN is connected with AC adapter, MP2607

regulates the SYS pin voltage at about 5V with

an internal low drop-out regulator. If IN is

connected with USB port, SYS is connected to

IN through an internal current limited switch. In

both cases, the battery charging is done

through a P-channel FET between IN and

BATT, so the input source supplies both load

current to SYS and charging current to BATT.

This P-channel FET on-resistance is designed

to be less than 0.3ohm to minimize the dropout

from IN to BATT. If the sum of SYS load current

and BATT charging current will exceed the

source current limit, either AC adapter or USB

port,

MP2607

automatically

reduces

the

charging current to comply with the source

current limit and satisfy SYS load demand (Fig2

and Fig3). For USB mode, if SYS load current

further increases beyond the source current

limit, SYS voltage will drop to below BATT and

MP2607 will turn on the 50mΩ N-channel

switch between BATT and SYS to allow battery

to supplement the system load (Fig3). The

control of this switch has two phases in this

where its voltage drop is regulated. This occurs

at low battery supplement current level; 2)

occurs at medium to high battery supplement

current level; Battery supplement mode ensures

the system load is always met and its operation

will not be disturbed.

IN is connected to a valid source, thus allow

automatic turn-off of the N-channel switch to

avoid overcharge when SYS pin voltage

recovers to rise above BATT pin voltage.

AC adaptor

current Limit

AC adaptor

Voltage

4.3V

Charging

current

AC adaptor

current

SYS load

current

Figure 2—Power Path Management for AC

Adapter Mode