8

LT1301

Capacitor Selection

Low ESR capacitors are required for both input and output

of the LT1301. ESR directly affects ripple voltage and

efficiency. For surface mount applications AVX TPS series

tantalum capacitors are recommended. These have been

specially designed for SMPS and have low ESR along with

high surge current ratings. For through-hole applications

Sanyo OS-CON capacitors offer extremely low ESR in a

small size. Again, if peak switch current is reduced using

smaller, higher ESR units can be used. Suggested capaci-

tor sources are listed in Table 2.

Diode Selection

Best performance is obtained with a Schottky rectifier

diode such as the 1N5817. Phillips Components makes

this in surface mount as the PRLL5817. Motorola makes

the MBRS130LT3 which is slightly better and also in

surface mount. For lower output power a 1N4148 can be

used although efficiency will suffer substantially.

Layout Considerations

The LT1301 is a high speed, high current device. The input

ground. Connect the PGND and GND (pins 8 and 1)

together under the package. Place the inductor adjacent to

SW (pin 7) and make the switch pin trace as short as

possible. This keeps radiated noise to a minimum.

Four-Cell to 5V Converter

C3

100µF

L2

33µH

0.1µF

5V OUTPUT

200mA

80 to 83% EFFICIENT

+

L1

33µH

C2

100µF

1N5817

C1

100µF

4 CELLS

SW

NC

PGND

GND

SENSE

LT1301

SELECT

LT1301 TAO3

SHDN

SHUTDOWN

+

+

1N5817

2N4403

5V, 200mA

+

L1*

10µH

*SUMIDA CD54-100LC

COILCRAFT DO3316-223

100µF

100µF

470

Ω

0.1µF

2

×

AA

CELL

SW

PGND

GND

SENSE

LT1301

SELECT

LT1301 TA4

SHDN

NC

NC

SHUTDOWN

+

Step-Up Converter with Automatic Output Disconnect