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LTC4063

Standalone Linear Li-Ion Charger with Micropower Low Dropout Linear Regulator

Linear Technology 

LTC4063

PI FU CTIO S

BAT (Pin 1): Charger Output and Regulator Input. This pin

provides charge current to the battery and regulates the

final float voltage to 4.2V. This pin also supplies power to

the LDO regulator.

OUT (Pin 2): LDO Regulator Output. This pin should be

bypassed with a ≥ 2µF low ESR capacitor as close to the

pin as possible for best performance. The minimum VOUT

is 1.2V.

FB (Pin 3): Regulator Feedback Input. The voltage on this

pin is compared to the internal reference voltage (800mV)

by the error amplifier to keep the output voltage in regula-

tion. An external resistor divider between OUT and FB sets

the output voltage.

LDOEN (Pin 4): LDO Enable Input. A logic high on the

LDOEN pin shuts down the LDO. In this state, OUT

becomes high impedance and the battery drain current

drops to less than 5µA. A logic low on the LDOEN pin

enables the LDO regulator. A 2M pull-down resistor de-

faults the LDO to its enabled state.

CHGEN (Pin 5): Charger Enable Input. A logic high on the

CHGEN pin places the charger into shutdown mode, where

the ICC quiescent current is less than 65µA. A logic low on

this pin enables battery charging. A 2M pull-down resistor

to ground defaults the charger to its enabled state.

CHRG (Pin 6): Open-Drain Charge Status Output. The

charge status indicator pin has two states: pull-down and

high impedance. This output can be used as a logic

interface or an LED driver. In the pull-down state, an

NMOS transistor capable of sinking 10mA pulls down on

the CHRG pin. The state of this pin is dependent on the

value of IDETECT as well as the termination method being

used. See Applications Information.

TIMER (Pin 7): Timer Program and Termination Select

Pin. This pin selects which method is used to terminate the

charge cycle. Connecting a capacitor, CTIMER, to ground

selects Charge Time termination. The charge time is set by

the following formula:

Time (Hours) = 3 Hours • CTIMER or

0.1µF

CTIMER

=

0.1µF

•

Time (Hours)

3 (Hours)

Connecting the pin to ground selects Charge Current

termination, while connecting the pin to VCC selects User

termination. See Applications Information.

IDET (Pin 8): Current Detection Threshold Program Pin.

The current detection threshold, IDETECT, is set by con-

necting a resistor, RDET, to ground. IDETECT is set by the

following formula:

IDETECT

=

RPROG

10RDET

• ICHG

= 100V

RDET

or

RDET

=

100V

IDETECT

The CHRG pin becomes high impedance when the charge

current drops below IDETECT. IDETECT can be set to 1/10th

the programmed charge current by connecting IDET di-

rectly to PROG. See Applications Information.

This pin is clamped to approximately 2.4V. Driving this pin

to voltages beyond the clamp voltage can draw large

currents and should be avoided.

PROG (Pin 9): Charge Current Program and Charge Cur-

rent Monitor. The charge current is set by connecting a

resistor, RPROG, to ground. When charging in constant

current mode, this pin servos to 1V. The voltage on this pin

can be used to measure the charge current using the

following formula:

IBAT

=

VPROG

RPROG

• 1000

VCC (Pin 10): Positive Input Supply Pin. Provides power to

the battery charger. This pin should be bypassed with a

1µF capacitor.

Exposed Pad (Pin 11): Ground. This pin is the back of the

Exposed Pad package and must be soldered to the PCB

copper for minimal thermal resistance.

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