MP2633A – 1.5A SINGLE CELL SWITCH MODE BATTERY CHARGER

MP2633A Rev. 1.03

www.MonolithicPower.com

24

4/27/2016

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If charging remains in TC mode beyond the

terminate. The following determines the length of

the trickle-charge period:

)

A

(

I

A

1

F

1

.

0

)

F

(

C

s

min

60

CHG

TMR

TMR

_

TRICKLE













(1)

The maximum total charge time is:

)

A

(

I

A

1

F

1

.

0

)

F

(

C

Hours

6

CHG

TMR

TMR

_

TOTAL













(2)

Negative Temperature Coefficient (

for Battery Temperature Monitoring

The MP2633A has a built-in NTC resistance

window comparator, which allows the MP2633A

to monitor the battery temperature via the

battery-integrated

thermistor.

Connect

an

connect the thermistor from the NTC pin to GND.

The resistor divider determines the NTC voltage

depending on the battery temperature. If the NTC

voltage falls outside of the NTC window, the

MP2633A stops charging. The charger will then

restart if the temperature goes back into NTC

window range.

Input-Current Limiting in Charge Mode

The MP2633A has a dedicated pin that programs

the input-current limit. The current at ILIM is a

fraction of the input current; the voltage at ILIM

indicates the average input current of the

switching regulator as determined by the resistor

value between ILIM and GND. As the input

current approaches the programmed input

current limit, charge current is reduced to allow

priority to system power.

Use the following equation to determine the input

current limit threshold,

ILIM

ILIM

40.5(kΩ)

I=

(A)

R(kΩ)

(3)

Input Over-Current Protection

The

MP2633A

features

input

over-current

protection (OCP): when the input current

exceeds 3A, Q2 is controlled linearly to regulate

the current. If the current still exceeds 3A after a

120µs blanking time, Q2 will turn off. A fast off

function turns off Q2 quickly when the input

current exceeds 7A to protect both Q1 and Q2.

Setting the Charge Current

CHG

ISET

70(kΩ)

40(mV)

I(A)=

R(kΩ)RS1(mΩ)



(4)

Where the 40mV is the charge current limit

always.

Battery Short Protection

The MP2633A has two current limit thresholds.

CC and CV modes have a peak current limit

threshold of 3A, while TC mode has a current

limit threshold of 1.5A. Therefore, the current limit

threshold decreases to 1.5A when the battery

voltage drops below the TC threshold. Moreover,

the switching frequency also decreases when the

BATT voltage drops to 40% of the charge-full

voltage.

Thermal Foldback Function

The MP2633A implements thermal protection to

prevent thermal damage to the IC and the

surrounding components. An internal thermal

sense

and

feedback

loop

automatically

decreases the programmed charge current when

the die temperature reaches 120°C. This function

is called the charge-current-thermal foldback. Not

only does this function protect against thermal

damage, it can also set the charge current based

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 MP2633A integrates indicators for the

following conditions as shown in Table 2.