9

LTC4065/LTC4065A

4065fb

SI

PLIFIED BLOCK DIAGRA S

Figure 1b. LTC4065A Block Diagram

–

+

–

+

–+

–+

2

+

MP

M2

×1

M1

×1000

R1

R2

ENABLE

4V

R3

R4

R5

2.9V

CHRG

6

PROG

1

GND

4056 F01b

BAT

1V

PROG

C/10

C2

C3

0.1V

1.2V

3.6V

0.1V

D2

D3

D1

115

°C

1.2V

REF

CA

MA

LOBAT

–

+

C1

VA

5

ACPR

3

4

BAT

LOGIC

COUNTER

OSCILLATOR

SHUTDOWN

CHARGE CONTROL

–

+

TA

OPERATIO

The LTC4065 is a linear battery charger designed primarily

for charging single cell lithium-ion batteries. Featuring an

internal P-channel power MOSFET, the charger uses a

constant-current/constant-voltage charge algorithm with

programmable current. Charge current can be programmed

up to 750mA with a final float voltage accuracy of

±0.6%.

The CHRG open-drain status output indicates if C/10 has

been reached. No blocking diode or external sense resistor

is required; thus, the basic charger circuit requires only

two external components. The ACPR pin (LTC4065A)

monitors the status of the input voltage with an open-drain

output. An internal termination timer and trickle charge

low-battery conditioning adhere to battery manufacturer

safety guidelines. Furthermore, the LTC4065 is capable of

operating from a USB power source.

An internal thermal limit reduces the programmed charge

current if the die temperature attempts to rise above a

preset value of approximately 115

°C. This feature protects

the LTC4065 from excessive temperature and allows the

user to push the limits of the power handling capability of

a given circuit board without risk of damaging the LTC4065

or external components. Another benefit of the LTC4065

thermal limit is that charge current can be set according to