EC49022 datasheet(6/8 Pages) E-CMOS

6 / 8 page

1A, Single Cell Linear Lithium Battery Charger

E-CMOS Corp. (www.ecmos.com.tw)

Page 6 of 8

4J30N Rev. F001

EC49022

current can be set according to typical, not worst-case, ambient temperatures for a given application with the

assurance that the charger will automatically reduce the current in worst-case conditions.

The charge cycle begins when the voltage at the VCC pin rises above the UVLO level, a current set resistor

is connected from the PROG pin to ground, and the CE pin is pulled above the chip enable threshold. The CHRG

pin outputs a logic low to indicate that the charge cycle is on going. At the beginning of the charge cycle, if the

battery voltage is below 3V, the charge is in recharge mode to bring the cell voltage up to a safe level for

charging. The charger goes into the fast charge constant-current mode once the voltage on the BAT pin rises

above 3 V. In constant current mode, the charge current is set by RPROG. When the battery approaches the

regulation voltage 4.3V, the charge current begins to decrease as the EC49022 enters the constant-voltage

mode. When the current drops to charge termination threshold, the charge cycle is terminated, and CHRG pin

assumes a high impedance state to indicate that the charge cycle is terminated and STDBY pin is pulled low.

The charge termination threshold is 10% of the current in constant current mode. To restart the charge cycle,

remove the input voltage and reapply it, or momentarily force CE pin to 0V. The charge cycle can also be

automatically restarted if the BAT pin voltage falls below the recharge threshold. The on-chip reference voltage,

error amplifier and the resistor divider provide regulation voltage with 1% accuracy which can meet the

requirement of lithium-ion and lithium polymer batteries. When the input voltage is not present, or input voltage is

below VBAT, the charger goes into a sleep mode, dropping battery drain current to less than 1

μA. This greatly

reduces the current drain on the battery and increases the standby time. The charger can be shutdown

by forcing the CE pin to GND.

Programming charge current

The charge current is programmed using a single resistor from the PROG pin to ground. The program resistor

and the charge current are calculated using the following equations.:

In application, according the charge current to determine RPROG ,the relation between RPROG and charge current

can reference the following chart：

RPROG (k)

IBAT (mA)

RPROG (k)

IBAT (mA)

1.86

600

18.6

1.55

720

9.3

120

1.4

800

4.6

240

1.24

900

3.73

300

1.12

1000

2.8

400

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