MP2633 – 1.5A SINGLE CELL SWITCH MODE BATTERY CHARGER

MP2633 Rev. 1.05

www.MonolithicPower.com

25

4/19/2013

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

© 2013 MPS. All Rights Reserved.

on

requirements

rather

than

worst-case

conditions

while

ensuring

safe

operation.

Furthermore, the part includes thermal shutdown

protection where the ceases charging if the

junction temperature rises to 150°C.

Fully Operation Indication

The MP2633 integrates indicators for the

following conditions as shown in Table 2.

Table 2: Indicator for Each Operation Mode

Operation

ACOK

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

CHG

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

BOOST

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

Charging

Low

End of Charge, charging disabled

High

Charge Mode

NTC Fault, Timer Out

Low

Blinking

High

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 MP2633 allows for true output disconnect by

eliminating body diode conduction of the internal

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

In the boost mode, the MP2633 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 MP2633 turns off the boost converter. Once

restarts again as long as the MODE pin remains

in active status.

Boost Output-Current Limiting

The MP2633 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 1.5A as per the following

equation:

7

.

1

)

m

((

1

RS

)

mV

(

40

)

k

(

R

)

k

(

70

)

A

(

I

OLIM

OLIM

×

Ω

×

Ω

Ω

=

(6)

Where: the 40mV is the charge current limiting

reference.

SYS Output Over Current Protection

The MP2633 integrates three-phase output over-

current protection.

Phase one (boost mode): when the output

current exceeds the output current limit, the