MP2661 datasheet(17/35 Pages) MPS

17 / 35 page

MP2661 – 0.5A, 1-CELL CHARGER W/ I2C CONTROL AND POWER PATH

MP2661 Rev. 1.03

www.MonolithicPower.com

4/9/2018

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

The charge current is terminated at the same

time if TERM_TMR is set via Reg05[0] = 0;

otherwise, the charge current keeps tapering off.

If EN_BF = 0, the termination function is

disabled, the above actions will not occur.

During the charging process, the actual charge

current may be less than the register setting

due to other loop regulations, such as dynamic

power management (DPM) regulation (input

voltage, input current) or thermal regulation. If

the input current or the input voltage reach their

limits during the CV charge, the charge full

termination is not influenced when the charge

current is not so close to the EOC current

specification.

A new charge cycle starts when the following

conditions are valid:

 The input power is recycled

 Battery charging is enabled by the I2C

 Auto-recharge kicks in

Under the following conditions:

 No thermistor fault at NTC

 No safety timer fault

 No battery over-voltage

 BATFET is not forced to turn off

Automatic Recharge

When the battery is fully charged and the

charging is terminated, the battery may be

discharged due to system consumption or self-

discharge.

When

the

battery

voltage

discharged below the recharge threshold, and

VIN is still in the operation range, the IC begins

another new charging cycle automatically

without the requirement of restarting a charging

cycle manually.

The auto-recharge function is valid only when

EN_BF =1 and TERM_TMR=0.

Battery Over-Voltage Protection (OVP)

The IC is designed with a built-in battery over-

voltage limit about 130mV higher than VBATT_REG.

When the battery over-voltage event occurs,

the IC suspends the charging immediately and

asserts a fault.

Input Current and Input Voltage Based

Power Management

To meet the input source (usually USB)

maximum current limit specification, the IC uses

input current-based power management by

monitoring the input current continuously. The

total input current limit can be programmed via

the I2C to prevent the input source from

overloading.

If the pre-set input current limit is higher than

the rating of the input source, back-up input

voltage-based power management also works

to prevent the input source from being

overloaded. If either the input current limit or the

input voltage limit is reached, the Q1 MOSFET

between IN and SYS are regulated so that the

total input power is limited. As a result, the

system voltage drops. Once the system

declines to the minimum value of 4.56V or VIN-

160mV, the charge current is reduced to

prevent the system voltage from dropping

further.

Voltage-based DPM regulates the input voltage

to VIN_REG when the load is over the input power

capacity. VIN_REG set via the I

2C should be at

least 400mV higher than VBATT_REG to ensure the

stable operation of the regulator.

Battery Supplement Mode

The charge current is reduced to keep the input

current or input voltage in regulation when DPM

occurs. If the charge current is at zero, and the

input source is still overloaded due to a heavy

system load, the system voltage starts to fall off.

Once the system voltage falls below the battery

voltage, the IC enters battery supplement mode.

When the system voltage is 30mV below the

battery voltage, the ideal diode mode is

enabled. The battery MOSFET is regulated to

maintain

VBATT-VSYS

22.5mV.

the

supplement current IDSG*RON_BATT is higher than

22.5mV, the battery MOSFET is fully turned on

to keep the ideal forward voltage. When the

system load decreases, once VSYS is higher

than VBATT+20mV, ideal diode mode is disabled.

Figure

shows

the

dynamic

power

management and battery supplement mode

operation profile.

MP2661 Datasheet(PDF) 17 Page - Monolithic Power Systems

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