LT3494/LT3494A

1

3494fb

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Micropower Low Noise

Boost Converters with

Output Disconnect

The LT

with integrated power switch, Schottky diode and output

disconnect circuitry. The parts use a novel* control tech-

nique resulting in low output voltage ripple as well as high

efficiency over a wide load current range. This technique

guarantees that the switching frequency stays above the

audio band for the entire load range. The parts feature a high

performance NPN power switch with a 350mA and 180mA

current limit for the LT3494A and LT3494 respectively. The

quiescent current is a low 65μA, which is further reduced

to less than 1μA in shutdown. The internal disconnect

circuitry allows the output voltage to be isolated from the

input during shutdown. An auxiliary reference input (CTRL

pin) overrides the internal 1.225V feedback reference with

any lower value allowing full control of the output voltage

during operation. The LT3494/LT3494A are available in a

tiny 8-lead 3mm

× 2mm DFN package.

OLED Power Supply from One Li-Ion Cell

65μA in Active Mode

1μA in Shutdown Mode

Load Range

350mA Current Limit (LT3494A)

180mA Current Limit (LT3494)

× 2mm DFN Package

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

*Patent pending.

SW

CAP

SHDN

CTRL

FB

GND

2.21M

3494 TA01a

LT3494

4.7

μF

2.2

μF

15

μH

0.22

μF

3V

TO 4.2V

16V

16mA

LOAD CURRENT (mA)

0.1

0

10

15

1

10

100

3494 TA01b

5

LT3494

FIGURE 5 CIRCUIT

100MHz MEASUREMENT BW

LOAD CURRENT (mA)

0.1

60

70

80

90

1

10

100

3494 TA01c

50

40

30

20

160

200

240

280

120

80

40

0

LOAD FROM

CAPACITOR

LOAD FROM

Output Voltage Ripple

vs Load Current

Efficiency and Power Loss

vs Load Current