LT1534-1 LINER [Linear Technology], LT1534-1 Datasheet - Page 13

• Manufacturer Part Number: LT1534-1
• Description: Ultralow Noise 2A Switching Regulators
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
2. Calculate peak inductor current at full load current to
TYPICAL APPLICATIO S
ensure that the inductor will not saturate. Peak current
can be significantly higher than output current, espe-
cially with smaller inductors and lighter loads, so don’t
omit this step. Powdered iron cores are forgiving be-
cause they saturate softly, whereas ferrite cores satu-
rate abruptly. Other core material falls in between. The
following formula assumes continuous mode opera-
tion but it errors only slightly on the high side for dis-
continuous mode, so it can be used for all conditions.
L = inductance value
V
V
I = output current
f = oscillator frequency
I
PEAK
IN
OUT
= supply voltage
= output voltage
2.7V TO 10V
2700pF
I
OUT
16.9k
10k
0.047 F
12
11
4
5
6
V
V
OUT
C
R
SHDN
SYNC
V
U
Low Noise 12V Dual Output Flyback Converter with Dual Polarity Output Voltage Sensing
IN
T
T
C
GND
10 F
LT1534-1
1,8,
9,16
V
IN
INFORMATION
15
U
V
NFB
2
P6KE-20A
IN
PGND
R
R
10
1N4148
COL
• • •
VSL
CSL
2.49k
1%
FB
L f V
V
OUT
2
3
14
13
7
U
W
–
NOTE 1
OUT
V
IN
9.31k
1%
10
1
9
2
NOTE 1: 25nH TRACE INDUCTANCE
OR COILCRAFT B10T
L1, L2: COILTRONICS CTX50-4
10
T1
1nF
4
8
3
7
U
MBR330
MBR330
+
+
C1
47 F
C2
47 F
2.49k
1%
3. Choose a core geometry. For low EMI problems a
4. Select an inductor that can handle peak current, aver-
5. Finally, double check output voltage ripple. The experts
Further Help
AN70 has more information on noise in switching regula-
tors and its measurement. AN19 has general information
on switcher design. The Linear Technology applications
group is always ready to lend a helping hand.
21.5k
1%
closed structure should be used such as a pot core, ER
core, E core or toroid (see AN70 appendix I).
age current (heating effects) and fault current.
in the Linear Technology Applications department have
experience with a wide range of inductor types and can
assist you in making a good choice.
50 H
50 H
T1: PHILIPS EFD-15-3F3 CORE
L1
L2
OPTIONAL
GAP FOR PRIMARY
+
+
L = 100 H
47 F
47 F
12V
50mA
– 12V
50mA
LT1534/LT1534-1
PIN 1 TO TO 10, 16 TURNS 24AWG
PIN 3 TO 8, 45 TURNS 38AWG
PIN 4 TO 7, 45 TURNS 36AWG
PIN 2 TO 9, 16 TURNS 24AWG
1534 TA04
13