7
LT1301
EFFICIENCY (%) COMPONENT
PART NUMBER VENDOR L (
µ
H) DCR (Ω)V
IN
(V) I
LIM
PIN 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 — —
APPLICATIONS INFORMATION
WUU
U
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-
tion with the I
LIM
pin. Efficiency is significantly affected by
inductor DCR. For best efficiency limit the DCR to 0.03Ω
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
SWITCH CURRENT (mA)
700
800
1000
1100
100 10k 100k 1M
LT1301 F8
300
1k
900
600
400
1.6V ≤ V
IN
≤ 5V
