LTC3803-3 Datasheet, PDF (16/16 Pages) Linear Technology – Constant Frequency Current Mode Flyback DC/DC Controller in ThinSOT

LTC3803-3
TYPICAL APPLICATIO S
90% Efficient Synchronous Flyback Converter
V_IN
36V TO 72V
220k
T1
• ^Q2
C_IN
•
V_OUT*
3.3V
1.5A
C_O
1n
33k ₁
6
I_TH/RUN GATE
2
LTC3803-3
GND
V_CC
5
8.06k
3
4
V_FB = 0.8V SENSE
25.5k*
R_FB
V_OUT
10μF
10V
Q1
560Ω
4.7k
R_CS
D1
•
0.1μF
38033 TA04a
T1: PULSE ENGINEERING PA1006
Q1: FAIRCHILD FDC2512
Q2: VISHAY Si9803
D1: PHILIPS BAS516
C_IN: TDK 1μF, 100V, X5R
C_O: TDK 100μF, 6.3V, X5R
R_CS: VISHAY OR IRC, 80mΩ
*FOR 5V OUTPUT CHANGE R_FB TO 42.2k
Efficiency vs Load
100
V_OUT = 3.3V
95
90
85
80
75
70
500
V_IN = 36V
V_IN = 48V
V_IN = 60V
V_IN = 72V
750 1000 1250 1500 1750 2000
LOAD CURRENT (mA) 38083 TA04b
Efficiency vs Load
100
V_OUT = 5V*
95
90
85
80
75
70
500
V_IN = 36V
V_IN = 48V
V_IN = 60V
V_IN = 72V
750 1000 1250 1500 1750 2000
LOAD CURRENT (mA) 38083 TA04c
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Burst Mode is a registered trademark of Linear Technology Corporation. No R_SENSE is a trademark of Linear Technology Corporation.
16 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ^● FAX: [phone] ^● www.linear.com
38033fa
LT 0407 • PRINTED IN THE USA
© LINEAR TECHNOLOGY CORPORATION 2006