LTC4059/LTC4059A

5

4059fb

PI FU CTIO S

GND (Pins 1, 7): Ground/Exposed Pad. The exposed

package pad is ground and must be soldered to the PC

board for maximum heat transfer.

Li CC (Pin 2, LTC4059): Li-Ion/Constant Current Input

thereby providing a constant current to the BAT pin. This

feature is useful for charging Nickel chemistry batteries.

Tie to GND if unused.

ACPR (Pin 2, LTC4059A): Open-Drain Power Supply

lockout threshold, the ACPR pin will pull to ground;

otherwise the pin is forced to a high impedance state.

BAT (Pin 3): Charge Current Output. Provides charge

current to the battery and regulates the final float voltage

to 4.2V. An internal precision resistor divider from this pin

sets this float voltage and is disconnected in shutdown

mode.

to 8V. This pin should be bypassed with at least a 1

µF

voltage, the LTC4059 enters shutdown mode, dropping

PROG (Pin 5): Charge Current Program and Charge Cur-

programs the charge current. When charging in constant-

current mode, this pin servos to 1.21V. In all modes, the

voltage on this pin can be used to measure the charge

current using the following formula:

I

V

R

BAT

PROG

PROG

=

• 1000

EN (Pin 6): Enable Input Pin. Pulling this pin above the

the LTC4059 in shutdown mode, thus terminating a charge

cycle. In shutdown mode, the LTC4059 has less than 25

µA

supply current and less than 1

µA battery drain current.

Enable is the default state, but the pin should be tied to

GND if unused.