MP2617A, MP2617B

– SINGLE CELL SWITCHING CHARGER WITH POWER PATH

MP2617A, MP2617B Rev. 1.23

www.MonolithicPower.com

16

1/15/2018

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© 2018 MPS. All Rights Reserved.

Introduction

The MP2617A and MP2617B is a switching

charger IC, with integrated smart power path

management for

powering

the system

and

charging a single cell battery simultaneously and

independently.

The MP2617A and MP2617B includes input DC-

DC step down converter for wide range of DC

sources and USB inputs. It has precision average

input current limit to make maximum use of the

allowable input power. This feature allows fast

charging when powering from an USB port, and

ensures the input current never exceeds the

input power specification especially when the

input power comes from a USB port. Additionally,

the

input

current

limit

threshold

can

be

programmed by logic inputs or a resistor to

ground from the ILIM pin.

The MP2617A and MP2617B implements an on-

chip 4

0mΩ MOSFET which works as a full-

featured linear charger with trickle charge, high

accuracy constant current and constant voltage

charge, charge termination, auto recharge, NTC

monitor, built-in timer control, charge status

indication, and thermal protection. The charge

current can be programmed by an external

resistor connected from the ISET pin to AGND.

The IC limits the charge current when the die

temperature exceeds 120°C.

The 4

0mΩ MOSFET works as an ideal diode to

connecting the battery to the system load when

the input power is not enough to power the

system load. When the input is removed, the

40m

Ω MOSFET is turned on allowing the battery

to power up the system.

With smart power path management, the system

load is satisfied in priority then the remaining

current is used to charge the battery. The

MP2617A and MP2617B will reduce charging

current or even use power from the battery to

satisfy the system load when its demand is over

the input power capacity.

Figure 1 shows the function block diagram of the

MP2617A and MP2617B.

DC-DC Step Down Converter

The DC-DC converter is a 1.6MHz step-down

switching regulator to provide the input power to

the

SYS,

which

drives

the combination of the system load and battery

charger. The regulator contains input current

measurement and control scheme to ensure the

average input current remains below the level

programmed via ILIM pin or logic inputs M0&M1.

This meets the adapter capacity limit or stays in

compliance with USB specification.

When the input voltage is higher than UVLO and

280mV higher than the battery voltage, input

voltage OK signal is active (ACOK

——————

turns low) and

the DC-DC converter soft-starts. If the input

power is sufficient to supply the combination of

the system load and battery charger, and the

input current limit loop is not triggered. The

above the battery voltage to minimize the power

loss of the battery charger during fast charging.

the system immediately even when a drained

battery is inserted to be charged. Figure 2 shows

System voltage can also be regulated to any

value between 4.08V to 4.4V in MP2617B (4.22V

to 4.63V in MP2617A) by using a resistor divider

on the SYSFB pin. This is shown as R6 and R7

in Figure 10. If the SYSFB is left floating, the

as Figure 2.

The converter adopts fixed off-time control to

extend the duty cycle (close to 100%) when the

4.4V

4.2V

3.6V

4.2V

3.4V

200mV

Figure 2

— MP 2617B SYS Regulation

Output