Datasheet

15
LT1767/LT1767-1.8/
LT1767-2.5/LT1767-3.3/LT1767-5
sn1767 1767fas
APPLICATIONS INFORMATION
WUU
U
3.3V, 1A
* ONLY REQUIRED IF INPUT CAN SINK >10mA
REMOVABLE
INPUT
0.1µF
1.5nF
83k
UPS120
1767 F09
2.2µF
UPS120*
CMDSH-3
5µH
2.2µF
BOOST
LT1767-3.3
V
IN
V
SW
FBSHDN
GND
V
C
SYNC
ALTERNATE
SUPPLY
28.5k
4.7k
Figure 9. Dual Source Supply with 6µA Reverse Leakage
Figure 10. Buck Converter with Adjustable Soft-Start
BOOST
LT1767-5
V
IN
OUTPUT
5V
1A
V
IN
12V
1767 F10
C2
0.1µF
C1
100µF
C
SS
15nF
C
C
330pF
D1
C3
2.2µF
D2
CMDSH-3
L1
5µH
R3
2k
V
SW
FB
SHDN
GND
V
C
SYNC
+
+
R4
47k
Q1
D1: UPS120
Q1: 2N3904
OUTPUT
5V
OUTPUT
–5V
†
* L1 IS A SINGLE CORE WITH TWO WINDINGS
BH ELECTRONICS #511-1013
†
IF LOAD CAN GO TO ZERO,
AN OPTIONAL PRELOAD OF 1k TO 5k
MAY BE USED TO IMPROVE LOAD REGULATION
D1, D3: UPS120
V
IN
6V TO 15V
GND
1767 F11
C2
0.1µF
C
C
330pF
D1
C1
100µF
10V TANT
C5
100µF
10V TANT
C3
2.2µF
16V
CERAMIC
C4
2.2µF
16V
CERAMIC
D2
CMDSH-3
D3
L1A*
9µH
L1B*
+
+
BOOST
LT1767-5
V
IN
V
SW
FBSHDN
GND
V
C
SYNC
Figure 11. Dual Output SEPIC Converter
during switch on time, causing current to flow, and energy
to build in L1B and C4. At switch off, the energy stored in
both L1B and C4 supply the –5V rail. This reduces the
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.
current in L1A and changes L1B current waveform from
square to triangular. For details on this circuit, including
maximum output currents, see Design Note 100.
PACKAGE DESCRIPTION
U
MSOP (MS8) 1100
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
0.021
± 0.006
(0.53 ± 0.015)
0
° – 6° TYP
SEATING
PLANE
0.007
(0.18)
0.043
(1.10)
MAX
0.009 – 0.015
(0.22 – 0.38)
0.005
± 0.002
(0.13 ± 0.05)
0.034
(0.86)
REF
0.0256
(0.65)
BSC
12
3
4
0.193 ± 0.006
(4.90 ± 0.15)
8
7
6
5
0.118 ± 0.004*
(3.00 ± 0.102)
0.118 ± 0.004**
(3.00 ± 0.102)
MS8 Package
8-Lead Plastic MSOP
(Reference LTC DWG # 05-08-1660)