ME4057

V01

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Page 8 of 18

IBAT (mA)

RPROG (K)

0.9

30

50

0.75

70

24

0.8

130

12

0.9

280

5.1

1

650

2

1.3

1000

1

Note:

a. K is the coefficient of variation, It generally is 1, but due to the vary operating environment, K is varied in the

range: 0.8~1.4

b. The up form is just for reference, it will varied ±10% according to the heat dissipation of the using PCB board;

c. The footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and

dissipate the heat to the surrounding ambient.

Charge termination

A charge cycle is terminated when the charge current falls to 1/10

th the programmed value after the final float

voltage is reached. This condition is detected by using an internal filtered comparator to monitor the PROG pin.

When the PROG pin voltage falls below 100mV for longer than tTEMP (typically 1.8mS), Charging is terminated. The

charge current is latched off and the ME4057 enters standby mode, where the input supply current drops to 55

μA

(Note:C/10 termination is disabled in trickle charging and thermal limiting modes).

When charging, transient loads on the BAT pin can cause the PROG pin to fall below 100mV for short periods

of time before the DC charge current has dropped to 1/10

th the programmed value. The 1.8mS filter time (t

TEMP) on

the termination comparator ensures that transient loads of this nature do not result in premature charge cycle

termination. Once the average charge current drops below 1/10

th the programmed value, the ME4057 terminated the

charge cycle and ceases to provide any current through the BAT pin. In this state all loads on the BAT pin must be

supplied by the battery.

The ME4057 constantly monitors the BAT pin voltage in standby mode. If this voltage drops below the 4.02V

recharge threshold (VRECHRG ),another charge cycle begins and current is once again supplied to the battery. To

manually restart a charge cycle when in standby mode, the input voltage must be removed and reapplied or the

charger must be shut down and restarted using the PROG pin. Figure 1 shows the state diagram of a typical charge

cycle.

Charge status indicator

ME4057 has two open-drain status indicator output

and

.

is pull-down when the ME4057 in

a charge cycle. In other status

in high impedance.

and

are all in high impedance when the

battery out of the normal temperature.

Represent in failure state, when TEMP pin in typical connecting, or the charger with no battery: red LED and

green LED all don’t light. The battery temperature sense function is disabled by connecting TEMP pin to GND. If

battery is not connected to charger,

pin outputs a PWM level to indicate no battery. If BAT pin connects a

10μF capacitor, the frequency of

flicker about 1-4S, If not use status indicator should set status indicator