2
DEMO MANUAL DC242
DC/DC CONVERTER
Figure 1. 100kHz Low Noise Step-Down Switching Regulator
TOP VIEW
S PACKAGE
16-LEAD PLASTIC SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
GND
NC
SHDN
V
CC
V
D
V
SW
SGND
GND
GND
NC
V
C
FB
SYNC
NC
V
IN
GND
LT1777CS
PARTS LIST
REFERENCE
DESIGNATOR
QUANTITY
PART NUMBER
DESCRIPTION
VENDOR
TELEPHONE
C1
1
0805ZC105MAT1A
1
µ
F 10V 20% X7R Capacitor
AVX
(843) 946-0362
C2
1
TPSD107M010R0065
100
µ
F 10V 20% Tantalum Capacitor
AVX
(207) 282-5111
C3, C6
2
06035A101JAT1A
100pF 50V 5% NPO Capacitor
AVX
(843) 946-0362
C4
1
63CV100BS
100
µ
F 63V 20% Electrolytic Capacitor
Sanyo
(619) 661-6835
C5
1
12061C104MAT1A
0.1
µ
F 100V 20% X7R Capacitor
AVX
(843) 946-0362
C7
1
06033A681JAT1A
680pF 25V 5% NPO Capacitor
AVX
(843) 946-0362
D1
1
10BQ100TR
100V 1A Schottky Diode
IR
(310) 322-3331
JP1, JP2
2
2802S-02G2
2mm 2-Pin Jumper
Comm Con
(626) 301-4200
JP1, JP2
2
CCIJ2mm-138-G
2mm 2-Pin Shunt
Comm Con
(626) 301-4200
L1
1
CTX200-4
200
µ
H 0.6A SMT Inductor
Coiltronics
(561) 241-7876
L2
1
SML32-470K
470nH 450mA SMT Inductor
Gowanda
(716) 532-2234
+
SYNC
SHDN
V
C
NC
NC
NC
SGND
6
5
13
1
8
9
16
12
3
14
2
11
15
7
V
SW
V
D
FB
GND
GND
GND
GND
U1
LT1777
V
IN
10
4
1
4
2
DC242 F01
3
D1
10BQ100
C2
100
µ
F
10V
C1
1
µ
F
10V
+
C4
100
µ
F
63V
C5
0.1
µ
F
100V
C6
100pF
C7
680pF
C3
100pF
R4
68k
R3
35.7k
1%
R2
26.1k
1%
JP1
V
OSEL
OPEN = 3.3V
CLOSE = 5V
R1
21.5k
1%
TP3
V
OUT
3.3V OR 5V
500mA
TP4
GND
L2
0.47
µ
H
SML32-470k
L1
200
µ
H
CTX200-4
V
CC
JP2
OPEN TO
EXT SYNC
TP2
V
IN
7.4V TO 48V
TP1
GND
TP6
SYNC
TP5
SHDN
SCHE ATIC A D PACKAGE DIAGRA S
U
W
W
