LTC4064

6

sn4064 4064fs

PI FU CTIO S

CHRG (Pin 1): Open-Drain Charge Status Output. When

the battery is being charged, the CHRG pin is pulled low by

an internal N-channel MOSFET. When the charge current

drops to 10% of the full-scale current, the N-channel

MOSFET latches off and a 30µA current source is con-

nected from the CHRG pin to ground. The C/10 latch can

be cleared by grounding the SHDN pin, momentarily, or

is removed, the current source is disconnected and the

CHRG pin is forced high impedance.

Bypass this pin with at least a 4.7µF ceramic capacitor to

ground.

FAULT (Pin 3): Open-Drain Fault Status Output. The

FAULT open-drain logic signal indicates that the charger

has timed out under trickle charge conditions or the NTC

comparator is indicating an out-of-range battery tempera-

begins whereby the charge current drops to one tenth of

its programmed value and the timer period is reduced by

a factor of four. When one fourth of the timing period has

stops and the FAULT pin latches to ground. The fault can

SHDN pin or pulling the BAT pin above 2.48V. If the NTC

comparator is indicating an out-of-range battery tempera-

ture condition, the FAULT pin will pull to ground until the

temperature returns to the acceptable range.

TIMER (Pin 4): Timer Capacitor. The timer period is set by

Short the TIMER pin to ground to disable the internal timer

function.

GND (Pins 5, 11): Ground. The exposed backside of the

package is also ground and must be soldered to the PC

board for maximum heat transfer.

NTC (Pin 6): Input to the NTC (Negative Temperature

Coefficient) Thermistor Temperature Monitoring Circuit.

With an external 10kΩ NTC thermistor to ground and a 1%

battery pack and stop charging when it is out of range.

ing is suspended and the internal timer is frozen. The

CHRG pin output status is not affected in this hold state.

The FAULT pin will be pulled to ground, but not latched.

When the temperature returns to an acceptable range,

charging will resume and the FAULT pin is released. The

NTC feature can be disabled by grounding the NTC pin.

PROG (Pin 7): Charge Current Program and Charge Cur-

rent Monitor Pin. The charge current is programmed by

stant-current mode, the LTC4064 servos the PROG pin

voltage to 1.5V. In all modes the voltage on the PROG pin

can be used to measure the charge current as follows:

SHDN (Pin 8): Shutdown Input Pin. Pulling the SHDN pin

to ground will put the LTC4064 into standby mode where

the BAT drain current is reduced to less than 3µA, and the

supply current is reduced to less than 25µA. For normal

BAT (Pin 9): Charge Current Output. A bypass capacitor of

at least 1µF with a 1Ω series resistor is required to keep the

loop stable when the battery is not present. A precision

internal resistor divider sets the final float potential on this

pin. The internal resistor divider is disconnected in sleep

and shutdown mode.

ACPR (Pin 10): Open-Drain Power Supply Status Output.

to ground. Otherwise, the pin is high impedance.