MP2633A – 1.5A SINGLE CELL SWITCH MODE BATTERY CHARGER

MP2633A Rev. 1.03

www.MonolithicPower.com

25

4/27/2016

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Table 2: Indicator for Each Operation Mode

Operation

ACOK

----------------

CHG

------------

BOOST

-------------------

Charge Mode

Charging

Low

Low

High

End of Charge, charging disabled

High

NTC Fault, Timer Out

Blinking

Boost Mode

High

High

Low

Sleep Mode, VCC absent

High

High

High

BOOST MODE OPERATION

Low-Voltage Start-Up

The minimum battery voltage required to start up

the circuit in boost mode is 2.9V. Initially, when

In this mode, the synchronous P-MOSFET stops

The P_MOSFET keeps off as long as the voltage

synchronous P-MOSFET enters a linear mode

allowing the inductor current to decrease and

normal closed-loop PWM operation is initiated. In

boost mode, the battery voltage can drop to as

low as 2.5V without affecting circuit operation.

SYS Disconnect and Inrush Limiting

The MP2633A allows for true output disconnect

by eliminating body diode conduction of the

during shutdown, drawing no current from the

input source. It also allows for inrush current

limiting at start-up, minimizing surge currents

from the input supply. To optimize the benefits of

output disconnect, avoid connecting an external

Schottky diode between the SW and SYS pins.

Board layout is extremely critical to minimize

voltage overshoot at the SW pin due to stray

inductance. Keep the output filter capacitor as

close as possible to the SYS pin and use very

low ESR/ESL ceramic capacitors tied to a good

ground plane.

Boost Output Voltage

The MP2633A programs the output voltage via

the external resistor divider at FB pin, and

provides built-in output over-voltage protection

(OVP)

to

protect

the

device

and

other

beyond 6V. Should output over-voltage occur,

the MP2633A turns off the boost converter. Once

restarts again as long as the MODE pin remains

in active status.

Boost Output-Current Limiting

The MP2633A integrates a programmable output

current limit function in boost mode. If the boost

output current exceeds this programmable limit

threshold, the output current will be limited at this

level and the SYS voltage will start to drop down.

The OLIM pin programs the current limit

threshold up to 1A as per the following equation:

OLIM

OLIM

70(kΩ)40(mV)

I(A)=

R(kΩ)RS1(mΩ)



(5)

Where the 40mV is the charge current limiting

reference.

SYS Output Over Current Protection

The MP2633A integrates three-phase output

over-current protection.

Phase one (boost mode): when the output

current exceeds the output current limit, the

output constant current loop controls the output

current, the output current remains at its limit of

remains in control, the boost converter enters

down mode and shutdown after a 120μs blanking

time.