MP2681B – CC/CV CONTROLLER WITH FULL PROTECTION

MP2681B Rev.1.0

www.MonolithicPower.com

14

12/22/2014

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Pre-

Charge

Detection

Battery-Regulation

Voltage

CV Charge

Detection

0A

Red LED

OFF

Green

LED ON

LEDR

LEDG

150mA

2-4A

Auto--

Recharge

Detection

Trickle Charge

CC Charge

CV Charge

0V

0V

Green

LED Flash

3.95V/cell

3.0V/cell

4.15V/cell

1.0V/cell

Figure 4. Typical Charge Profile

Charge Termination

The charge cycle is considered complete when

the charge current reaches the programmed

Figure 4 for a complete view of the charging

cycle and LED operation.

Automatic Re-Charge

The MP2681B allows the battery to be re-

charged automatically when the battery voltage

drops

below

the

auto-recharge

threshold

(3.95V/cell). The MP2681B re-sets the reference

voltage to the normal charging value and turns

on the CCON driver to re-start the charge cycle

LDO Output

The MP2681B implements a 5V LDO which

provides a pull-up voltage for the NTC, ID

resistor, and FLT detection. It supplies up to

20mA current. When VDD is higher than 5V, the

LDO output is regulated at 5V. If the VDD input

voltage is lower than 5V, the FET is fully on and

the LDO output is nearly equal to the input

voltage VDD.

Timer Operation

The MP2681B provides a safety timer in case of

a defective battery pack.

During pre-charge mode the charge timer is fixed

with a set capacity. During CC and CV charge

mode, the timer duration is proportional to the

charge rate. The timer will start counting every

time the charger process starts up (as in initial

power-up or automatic re-charge). The timer will

limit pre-charge time to T1 oscillating cycles on

TMR. If the charger stays in pre-charge mode for

longer than T1 cycles, the MP2681B terminates

the charging operation by disconnecting the

battery from the charger. The output voltage is

regulated to the default value. The timer-fault

indication is set by flashing LEDR and keeping

LEDG low. After a fault-reporting condition, the

charger can be re-initiated only by recycling the

power supply. The timer limit in the pre-charge

mode is fixed, and it will not change when the IC

is set to slow-charge or fast-charge mode via CR.