MP2617 – SINGLE CELL SWITCHING CHARGER WITH POWER PATH CONTROL

MP2617 Rev. 1.03

www.MonolithicPower.com

20

8/23/2013

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© 2013 MPS. All Rights Reserved.

When the timer out condition occurs, the MP2617

terminates the charge at once and CHGOK

_____________

blinks to indicate the fault status. If one of the

following events happens, the timer is refreshed

and MP2617 re-starts the charge cycle.

•

Input re-startup

•

Refresh EN

_____

/ISET signal

•

Auto-Recharge

NTC Thermistor

The NTC pin allows MP2617 to sense the battery

temperature

using

the

Negative

Thermal

Coefficient (NTC) thermistor usually available in

the battery pack to ensure safe operating

environment of the battery. A resistor with

appropriate value should be connected from VCC

to NTC and the NTC resistor is from NTC pin to

AGND. The voltage on NTC pin is determined by

the resistor divider whose divide ratio as the

different resistance of the NTC thermistor

depends on the ambient temperature of the

battery.

The MP2617 has an internal NTC voltage

comparator to set the upper and lower limit of the

divide ratio. If NTC pin voltage falls out of this

range it means the temperature is outside the

safe operating range,

As a result, The MP2617 will stop charging and

report it on indication pins. Charging will

automatically resume after the temperature falls

back into the safe range.

Thermal Protection

The MP2617 implements thermal protection to

prevent the thermal damage to the IC or

surrounding components. An internal thermal

sense and feedback loop will automatically

decrease the charge current when the die-

referred as charge current thermal fold-back.

This feature protects the MP2617 from excessive

temperature due to high power operation or high

ambient thermal conditions. Another benefit of

this feature is charge current can be set

according to the requirement rather than worst-

case conditions for a given application with the

assurance of safe operation. The MP2617 will

stop charging if the junction temperature rises

protection.

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

MP2617 controls the charge switch to work at the

charger switch exits the ideal diode mode, and

the charge cycle softly restarts.

Battery Discharge Protection

When the input power is removed or invalid, the

system load will draw power from the battery via

the battery switch. Under this condition, the

battery switch is fully on to minimize the power

loss. The MP2617 integrates battery discharge

protection. If the battery discharge current is

larger than the discharge current limit threshold

preset limited value. And if the current increases

further, the SYS voltage starts to decrease.

condition, the discharge current is limited at

200mA. In the event of a short from system to

GND the discharge current from the battery to

the system is also limited to 200mA.

Furthermore, battery voltage UVLO is always

monitored. If the battery voltage is lower than the

battery UVLO threshold, the battery switch is

turned off immediately. This feature makes sure

the battery from over-discharged.

Dynamic Power Path Management (DPPM)

In the presence of a valid input source, the PWM

converter will supply the current to both the

system and the battery charger.

3.4V, to ensure the system can still be powered