17
LT1533
TYPICAL APPLICATIONS
U
A 50V Output Low Noise Regulator. Cascoded Bipolar Transistors
Accommodate 60V Transformer Swings, Permitting 24V (20V
IN
to 30V
IN
)
Powered Operation. See AN70 for Details
Hysteretic Loop Lowers Quiescent Current to 100µA While
Maintaining Low Output Noise. See AN70 for Details
SHDN
DUTY
SYNC
COL A
COL B
PGND
R
VSL
R
CSL
FB
NFB
LT1533
GND
V
IN
2.7V TO 4V
(3 Ni-Cd BATTERIES)
14
2
15
16
13
12
7
11
3
4
5
6
10
3300pF
18k
0.01µF
10pF
5V
15k
L2
4.7µF
15k
+
T1
L1
100µH
L3
100µH
89
21.5k
1%
2.32k
1%
150k
1.18V
V
Z
INTERNAL
TO LTC1440
47µF
+
47µF
12V
1N4148
1N4148
L1, L3: COILTRONICS CTX100-3
L2: 22nH TRACE INDUCTANCE, FERRITE BEAD OR
INDUCTOR COILCRAFT B-07T TYPICAL
T1: CTX02-13665-X1
1553 TA05
+
C
T
R
T
V
C
OPTIONAL FOR
LOWEST RIPPLE
()
–
+
C1
LTC1440
SHDN
DUTY
SYNC
COL A
COL B
PGND
R
VSL
R
CSL
NFB
LT1533
GND
V
IN
24V
(20V TO 30V)
14
2
15
16
13
12
11
3
4
5
6
10
3300pF
18k
0.01µF
15k
3.3k
3.3k
L2
1µF
Q3
1N4148
68Ω
15k
+
T1
L1
100µH
50V
100µH
8
7
9
97.6k
1%
+ +
47µF
47µF
MUR110
MUR110
L1: COILTRONICS CTX100-3
L2: 22nH TRACE INDUCTANCE, FERRITE BEAD OR
INDUCTOR COILCRAFT B-07T TYPICAL
Q1, Q2: ZETEX ZTX-853
Q3: 2N2222A
T1: CTX02-13665-X1
1553 TA06
47µF
C
T
R
T
V
C
OPTIONAL FOR
LOWEST RIPPLE
()
360Ω
+
360Ω
68Ω
2.49k
1%
10k
1N752
5.6V
Q1
0.003µF
0.003µF
Q2
FB
