LT1737IGN Linear Technology, LT1737IGN Datasheet - Page 23

• Manufacturer Part Number: LT1737IGN
• Description: IC CNTRLR ISOLATD FLYBACK 16SSOP
• Manufacturer: Linear Technology
• Type: Flybackr

Specifications of LT1737IGN

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Frequency - Switching: 50kHz ~ 250kHz
• Voltage - Input: 4.1 ~ 20 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -

APPLICATION WITH 2-WINDING TRANSFORMER
The previous application example utilized a 3-winding
transformer, the third winding providing only feedback
information. Additional circuitry may be employed to
provide feedback information, thus allowing the trans-
former to be reduced to a 2-winding topology. (The cost
and size savings associated with the transformer often
TYPICAL APPLICATIO S
2N3906
Q1
C1: AVX TPS TANTALUM (TPSE226M035R0300)
C2: AVX TPS TANTALUM (TPSE336M025R0200)
D1, D3: MOTOROLA 100V, 1A SCHOTTKY DIODE
D2: SIGNAL DIODE
D4: 24V, 500mW ZENER DIODE
R3
3.01k
1%
90
80
70
60
50
40
30
20
1
C3
1nF
25V
X7R
D2
BAS16
8
7
Figure 13. Efficiency vs I
FB
V
OSCAP
C
V
6
IN
35.7k
1%
R2
3V
C5
47pF
50V
NPO
= 15V
10
SFST
OUT
V
IN
9
I
LOAD
3
= 12V
UVLO
t
ON
(mA)
14
10
R4
75k
5%
V
ENDLY
IN
100
U
= 18V
13
R8
240k
5%
R9
33k
5%
R5
150k
5%
MINENAB
LOAD
Figure 12. 12V-18V to Isolated 15V Converter
1737 F13
LT1737
12
R6
100k
5%
1000
M1: INT’L RECTIFIER 60V, 0.2Ω N-CH MOSFET
R
OCMP
V
CC
15
4
R7
4.7k
5%
R
CMPC
C8
0.1µF
25V
Z5U
5
C4
0.1µF
25V
Z5U
SGND
11
MBRS1100
make this a preferable alternative. Furthermore, a variety
of manufacturers offer off-the-shelf dual wound magnet-
ics which often can be applied as 1:1 transformers.)
Figure 12 shows an LT1737 configured for operation with
a dual wound toroid, the Coiltronics #CTX150-4
OCTA-PAC
voltage waveform is now provided by components Q1, R2,
OCTA-PAC is a trademark of Coiltronics, Inc.
I
1N5252
SENSE
PGND
GATE
1
D4
D3
1737 F12
22µF
35V
16
2
C1
+
5.1Ω
14.5
15.5
15.0
R10
5%
TM
. A ground referred version of the flyback
0
V
R11
100Ω
5%
IN
C6
470pF
50V
X7R
Figure 14. Load Regulation
COILTRONICS
1
2
CTX150-4
•
M1
IRFL014
T1
100
R1
0.27Ω
0.5W
IRC TYPE LR 2010
•
I
LOAD
3
4
(mA)
R12
100Ω
5%
C7
470pF
50V
X7R
200
MBRS1100
V
IN
D1
V
V
= 12V
IN
IN
+
= 15V
= 18V
1737 F14
C2
33µF
25V
300
LT1737
R13
7.5k
5%
23
V
15V
250mA
OUT
1737fa