Datasheet

15
LT1533
APPLICATIONS INFORMATION
WUU
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T he slew rate adjustment should be made by putting a
3.9k resistor in series with a 50k pot on the R
VSL
and R
CSL
pins (or a 2k resistor in series with a 25k pot with both
pins tied together). Monitor output noise or other system
signal while increasing the resistance until desired noise
performance is reached. System efficiency can also be
monitored.
While this topology is not as quiet as a push-pull con-
verter, it can provide a low cost, isolated power supply that
has decreased noise relative to other solutions.
More Help
AN70 contains much information concerning LT1533
applications and measurement of noise and should be
consulted. A 5V to 12V demo board is also available
(DC173). AN19 and AN29 also have general knowledge
concerning switching regulators. Our Application Depart-
ment is always ready to lend a helping hand.
TYPICAL APPLICATIONS
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Figure 6. 5V to ±12V DC Transformer
18k
10k
43k
LT1533
GND R
T
V
C
NFB FB
5V
22µF
10V
25nH*
T1**
L2
100µH
L1
100µH
68k
4k TO 68k
V
IN
DUTY
SHDN
SYNC
1
1
3.3
3.3
1533 F06
3300pF
12V
80mA
–12V
80mA
1N5819
×4
LT1121CS8
LT1175CS8
22µF
35V
22µF
35V
R4
150k
150k
2.2µF
25V
2.2µF
25V
332k
324k
81
32
1, 2, 7, 8
3
45
14
2
16
15
12
13
7
5V
8
10569
4
11
3
BAT85
BAT85
C
T
SHDN
* BEAD OR PCB TRACE
** COILTRONICS CTX02 13716-X1
L1, L2: COILCRAFT DT1608C-104
COL A

PGND
R
CSL
R
VSL
COL B