LT1534C View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LT1534C' PDF : 16 Pages View PDF
LT1534/LT1534-1
APPLICATIONS INFORMATION
2. Calculate peak inductor current at full load current to
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.
( ) IPEAK
=
IOUT
VOUT
VIN
+
VIN VOUT – VIN
2 • L • f • VOUT
L = inductance value
VIN = supply voltage
VOUT = output voltage
I = output current
f = oscillator frequency
3. Choose a core geometry. For low EMI problems a
closed structure should be used such as a pot core, ER
core, E core or toroid (see AN70 appendix I).
4. Select an inductor that can handle peak current, aver-
age current (heating effects) and fault current.
5. Finally, double check output voltage ripple. The experts
in the Linear Technology Applications department have
experience with a wide range of inductor types and can
assist you in making a good choice.
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.
TYPICAL APPLICATIO S
Low Noise ±12V Dual Output Flyback Converter with Dual Polarity Output Voltage Sensing
2.7V TO 10V
10µF
P6KE-20A
1N4148
12
SHDN
4 SYNC
15
VIN
2
COL
2700pF
5 CT
16.9k 6 RT
PGND 3
LT1534-1
14
RVSL
13
RCSL
11
VC GND
7
FB
NFB
10k
1,8,
9,16
0.047µF
10
2.49k
1%
MBR330
T1
1
7
+
10
4
2
8
+
9
3
NOTE 1
MBR330
10Ω
C1
47µF
C2
47µF
1nF
21.5k
1%
2.49k
1%
9.31k
1%
NOTE 1: 25nH TRACE INDUCTANCE
OR COILCRAFT B10T
L1, L2: COILTRONICS CTX50-4
L1
50µH
+
47µF
12V
50mA
+
47µF
L2
50µH
OPTIONAL
– 12V
50mA
T1: PHILIPS EFD-15-3F3 CORE
GAP FOR PRIMARY
L = 100µH
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
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