7

LT1300

COMPONENT

PART NUMBER

VENDOR

L (

DCR (

50mA LOAD

200mA LOAD

HEIGHT (mm)

PHONE NUMBER

DO1608-103

Coilcraft

10

0.11

Float

83

83

3.5

(708) 639–6400

DO3316-223

Coilcraft

22

0.050

Float

85

85

5.5

DO1608-223

Coilcraft

22

0.31

Ground

85

—

3.5

CTX10-1

Coiltronics

10

0.038

Float

85

85

4.2

(407) 241–7876

CTX20-1

Coiltronics

20

0.175

Ground

86

—

4.2

LQH3C2204K0M00

Murata-Frie

22

0.7

Ground

81

—

2.0

(404) 436–1300

CD54-100M

Sumida

10

0.11

Float

85

85

4.5

(708) 956–0666

CDRH62-220M

Sumida

22

0.38

Ground

84

—

3.0

CDRH62-100M

Sumida

10

0.17

Float

81

82

3.0

GA10-102K

Gowanda

10

0.038

Float

85

86

6.6 Through-Hole

(716) 532–2234

Table 1. Recommended Inductors

Inductor Selection

For full output power, the inductor should have a satura-

tion current rating of 1.25A for worst-case current limit,

although it is acceptable to bias an inductor 20% or more

into saturation. Smaller inductors can be used in conjunc-

inductor DCR. For best efficiency limit the DCR to 0.03

Ω

or less. Toroidal types are preferred in some cases due to

their closed design and inherent EMI/RFI superiority.

Recommended inductors are listed in Table 1.

Capacitor Selection

Low ESR capacitors are required for both input and output

of the LT1300. 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 application

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. Low frequency

output ripple can be reduced by adding multiple output

capacitors. If capacitance is reduced, output ripple will

increase. Suggested capacitor sources are listed in Table 2.

Table 2. Recommended Capacitors

VENDOR

SERIES

TYPE

PHONE#

AVX

TPS

Surface Mount

(803)448–9411

Sanyo

OS-CON

Through-Hole

(619) 661–6835

Panasonic

HFQ

Through-Hole

(201) 348–5200

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 LT1300 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.

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.