7

LT1301

EFFICIENCY (%)

COMPONENT

PART NUMBER

VENDOR

L (

30mA

60mA

120mA

HEIGHT (mm)

PHONE NUMBER

DO3316-333

Coilcraft

33

0.088

3.3

Open

84

84

85

5.5

(708) 639–6400

5

Open

89

89

90

DO1608-223

Coilcraft

22

.31

3.3

Open

82

82

—

3.5

3.3

Ground

85

—

—

5

10k

86

87

—

5

Ground

88

—

—

DO1608-103

Coilcraft

10

.11

2

Open

78

—

—

3.5

CTX20-1

Coiltronics

20

.175

3.3

Open

84

84

—

4.2

(407) 241-7876

5

Open

88

88

89

GA10-332

Gowanda

33

.077

3.3

Open

86

86

87

Through-Hole

(716) 532-2234

5

Open

89

89

90

LQH3G220K04M00

Murata-Erie

22

0.7

3.3

Ground

81

—

—

2.0

(404) 436-1300

5

Ground

85

—

—

CD73-330KC

Sumida

33

0.131

3.3

Open

84

85

86

3.5

(708) 956-0666

5

Open

88

88

89

CDRH62-330MC

Sumida

33

0.48

3.3

Open

80

80

81

3.0

Ground

85

—

—

5

Open

84

84

85

Ground

83

—

—

Table 1. Recommended Inductors

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

Table 2. Recommended Capacitors

switching. Zero load current causes the LT1301 to switch

so infrequently that C3 can completely discharge reducing

subsequent peak switch current to 400mA. If a load is

suddenly applied, output voltage will sag until C3 can be

recharged and peak switch current returns to 1A.

If the full capacity of the LT1301 is not required peak

current can be reduced by changing the value of R3 as

shown in Figure 8. With R3 = 0 switch current is limited to

approximately 400mA. Smaller, less expensive inductors

with lower saturation ratings can then be used.

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 inherent flux containment and EMI/RFI superiority.

Recommended inductors are listed in Table 1.

Figure 8. Peak Switch Current vs. Current Limit Set Resistor

CURRENT LIMIT SET RESISTOR (

Ω)

500

700

800

1000

1100

100

10k

100k

1M

LT1301 F8

300

1k

900

600

400

1.6V