MP2681 – CC/CV CONTROLLER WITH FULL PROTECTION

MP2681 Rev.1.01

www.MonolithicPower.com

12

12/25/2013

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FIGURE 4 — TYPICAL CHARGE PROFILE

Charge Termination

The charge cycle is considered complete when

the charge current reaches the programmed

Fig 4 for a complete view of the charging cycle

and LED’s operation.

Automatic Recharge

The

MP2681

allows

the

battery

to

be

automatically recharged when the battery voltage

drops below the auto-recharge threshold of

3.95V/cell. The MP2681 will automatically reset

the reference voltage to the normal charging

value and turn on the CCON driver to restart the

LDO Output

The MP2681 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, while if the VDD input voltage is

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

output nearly equals to the input voltage VDD.

Timer Operation

The MP2681 provides a safety timer in case of a

defective battery pack.

During pre-charge mode the charge timer is fixed

with a set capacity based on the battery

specifications. During CC and CV charge mode

the timer duration is proportional to the charge

rate. The timer will start counting after every time

the charger process starts such as initial power-

up or automatic recharge. The timer will limit pre-

charge time to T1 oscillating cycles on the TMR

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

longer than T1 cycles, the MP2681 will terminate

the charging operation by disconnecting the

battery from the charger. The output voltage is

regulated to the default value. The timer fault

indication will also be 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 the CR pin.