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FAX: (408) 434-0507
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www.linear.com
?LINEAR TECHNOLOGY CORPORATION 2008
LT 0509 REV A " PRINTED IN USA
TYPICAL APPLICATIONS
PART NUMBER DESCRIPTION
COMMENTS
LT1939
25V, 2A, 2.5MHz High Ef ciency DC/DC Converter and LDO Controller   V
IN(MIN)
= 3.6V, V
IN(MAX)
= 25V, V
OUT(MIN)
= 0.8V,
I
Q
= 2.5mA, I
SD
< 10糀, 3 ?3 DFN-10 Package
LT1940
Dual 25V, 1.4A (I
OUT
), 1.1MHz, High Ef ciency Step-Down DC/DC
Converter
V
IN(MIN)
= 3.3V, V
IN(MAX)
= 25V, V
OUT(MIN)
= 1.20V,
I
Q
= 3.8mA, I
SD
< 30糀, TSSOP16E Package
LT3480
36V with Transient Protection to 60V, 2A (I
OUT
), 2.4MHz, High Ef ciency
Step-Down DC/DC Converter with Burst Mode Operation
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 38V, V
OUT(MIN)
= 0.78V,
I
Q
= 70糀, I
SD
< 1糀, 3 ?3 DFN-10, MSOP-10E Package
LT3481
34V with Transient Protection to 36V, 2A (I
OUT
), 2.8MHz, High Ef ciency
Step-Down DC/DC Converter with Burst Mode Operation
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 34V, V
OUT(MIN)
= 1.26V,
I
Q
= 50糀, I
SD
< 1糀, 3 ?3 DFN-10, MSOP-10E Package
LT3493
36V, 1.4A (I
OUT
), 750kHz High Ef ciency Step-Down DC/DC Converter   V
IN(MIN)
= 3.6V, V
IN(MAX)
= 36V, V
OUT(MIN)
= 0.8V,
I
Q
= 1.9mA, I
SD
< 1糀, 2 ?3 DFN-6 Package
LT3500
36V, 40Vmax, 2A, 2.5MHz High Ef ciency DC/DC Converter and LDO
Controller
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 36V, V
OUT(MIN)
= 0.8V,
I
Q
= 2.5mA, I
SD
< 10糀, 3 ?3 DFN-10 Package
LT3501/10   25V, Dual 3A/2A (I
OUT
), 1.5MHz High Ef ciency Step-Down DC/DC
Converter
V
IN(MIN)
= 3.3V, V
IN(MAX)
= 25V, V
OUT(MIN)
= 0.8V,
I
Q
= 3.7mA, I
SD
= 10糀, TSSOP-20E Package
LT3505
36V with Transient Protection to 40V, 1.4A (I
OUT
), 3MHz, High Ef ciency
Step-Down DC/DC Converter
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 34V, V
OUT(MIN)
= 0.78V,
I
Q
= 2mA, I
SD
= 2糀, 3 ?3 DFN-8, MSOP-8E Package
LT3506/A    25V, Dual 1.6A (I
OUT
), 575kHz/1.1MHz High Ef ciency Step-Down DC/DC
Converter
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 25V, V
OUT(MIN)
= 0.8V,
I
Q
= 3.8mA, I
SD
= 30糀, TSSOP-16E, 5 ?4 DFN-16 Package
LT3508
36V with Transient Protection to 40V, Dual 1.4A (I
OUT
), 3MHz, High
Ef ciency Step-Down DC/DC Converter
V
IN(MIN)
= 3.7V, V
IN(MAX)
= 37V, V
OUT(MIN)
= 0.8V,
I
Q
= 4.6mA, I
SD
= 1糀, 4 ?4 QFN-24, TSSOP-16E Package
LT3684
34V with Transient Protection to 36V, 2A (I
OUT
), 2.8MHz, High Ef ciency
Step-Down DC/DC Converter
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 34V, V
OUT(MIN)
= 1.26V,
I
Q
= 850糀, I
SD
< 1糀, 3 ?3 DFN-10, MSOP-10E Package
LT3685
36V with Transient Protection to 60V, 2A (I
OUT
), 2.4MHz, High Ef ciency
Step-Down DC/DC Converter
V
IN(MIN)
= 3.6V, V
IN(MAX)
= 38V, V
OUT(MIN)
= 0.78V,
I
Q
= 70糀, I
SD
< 1糀, 3 ?3 DFN-10, MSOP-10E Package
ThinSOT is a trademark of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation.
12V to 5V, 3.3V, 1.8V and 1.6V with 1.5mm Maximum Height
RELATED PARTS
V
IN1
BOOST1
UVLO
OVLO
BOOST3
SW3
FB3
V
C3
TRK/SS3
BIAS
DRIVE
FB4
PGOOD1
PGOOD2
PGOOD3
PGOOD1
PGOOD2
PGOOD3
SW1
FB1
V
C1
TRK/SS1
BOOST2
0.1糉
10糉
33糉
D1
13.3k
1000pF
1.5nF
22.6k
L1 2糎
V
OUT1
1.8V
2A
V
IN
8V TO 16V
V
OUT2
3.3V
1.5A
D1: DIODES, INC. DFLS220L
D2, D3: DIODES, INC. DFLS120L
L1: COOPER SD14-2R0-R
L2, L3: COOPER SD14-4R5-R
Q1: ON SEMI NSS30071MR6T1G
L2 4.5糎
L3 4.5糎
V
IN2
V
IN3
V
INSW
49.9k
49.9k
4.02k
OVLO = 17V
UVLO = 7V
100k
11.3k
V
OUT1
V
OUT2
18.2k
SW2
FB2
V
C2
TRK/SS2
R
T
/SYNC
TRK/SS4
GND
LT3507
RUN1
RUN2
RUN3
0.1糉
0.1糉
10糉
D2
D3
7.32k
11.3k
SHDN
2000pF
1200pF
1.5nF
1.5nF
41.2k
11.8k
V
OUT2
V
OUT2
V
OUT1
20.0k
20.0k
3507 TA03
31.6k
f
SW
= 1.25MHz
2.2nF
13.3k
100k
100k
V
OUT3
5V
1.4A
V
OUT4
1.6V
0.2A
22糉
10糉
61.9k
Q1