Data Sheet

MP2636 –3.0A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 3.0A BOOST
MP2636 Rev.1.01 www.MonolithicPower.com 29
9/16/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
OPERATION
INTRODUCTION
The MP2636 is a highly-integrated, flexible,
synchronous switch-mode battery charger with
system power path management, designed for
single-cell Li-ion or Li-polymer batteries used in a
wide range of applications. Depending on the
status of the Input supply, the MP2636 can
operate in three modes: charge mode, boost
mode and sleep mode.
In charge mode, the MP2636 can work with
single cell Li-ion or Li-polymer battery. In boost
mode, MP2636 boosts the battery voltage to
V
SYS_SET
to power higher voltage system rails. In
sleep mode both charging and boost operations
are disabled and the device enters a sleep mode
to help reduce the overall power consumption.
The MP2636 monitors V
IN
to allow smooth
transition between different modes of operation.
CHARGER MODE OPERATION
Charge Cycle
In charge mode, the MP2636 has five control
loops to regulate input voltage, input current,
charge current, charge voltage and device
junction temperature. The MP2636 charges the
battery in three phases, trickle current (TC),
constant current (CC), and constant voltage (CV).
While charge operation is enabled, all five loops
are active but only one determines the IC
behavior. A typical battery charge profile is
depicted in Figure 11(a). The charger stays in TC
charge mode until the battery voltage reaches a
TC-to-CC threshold. Otherwise the charger
enters CC charge mode. When the battery
voltage rises to the CV-mode threshold, the
charger operates in constant voltage mode.
Figure 12(b) shows a typical charge profile when
the input-current-limit loop dominates during the
CC charge mode, and in this case the charger
maximizes the charging current due to the
switching-mode charging solution, resulting in
faster charging than a traditional linear solution.
Trickle charge
TC>>>CC
Threshold
CC>>>CV
Threshold
CC charge CV charge
I
CHG
V
BAT
Charge Full
Trickle
Charge
Current
Constant
Charge
Current
a) Without input current limit
Trickle charge
TC>>>CC
Threshold
CC>>>CV
Threshold
CC charge CV charge
I
CHG
V
BAT
Charge Full
Trickle
Charge
Current
Constant
Charge
Current
b) With input current limit
Figure 11: Typical Battery Charge Profile
Auto-recharge
Once the battery charge cycle completes, the
charger remains off. During this time, the external
load may consume battery power, or the battery
may self discharge. To ensure the battery will not
go into depletion, a new charge cycle
automatically begins when the battery voltage
falls below the auto-recharge threshold when the
input power is present. The timer is reset when
the auto-recharge cycle begins.
During the off state after the battery is fully
charged, if the input power re-starts or the EN
signal refreshes, the charge cycle will start and
the timer will re-set no matter what the battery
voltage is.
Battery Over-Voltage Protection
The MP2636 has battery over-voltage protection.
If the battery voltage exceeds the battery over-
voltage threshold, (102.5% of the battery full
voltage), charging is disabled. Under this
condition, an internal 5k dummy load draws a
current from the BATT pin to decrease the
battery voltage and protect the battery.