OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

LT1725IGN#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28
22
LT1725
1725fa
TYPICAL APPLICATIO S
U
Figure 9. 48V to Isolated 15V Converter
R2
0.1Ω
M1
IRF620
T1
VP5-0155
R12
5.1Ω
V
OUT
15V
1725 F09a
R7
51k
R6
51k
C7
47pF
6314
109
8
7
13 12 4 5
15
11 1
2
16
C6
1nF
R8
6.2k
R11
150Ω
D3
1N5257
D4
1N5257
D2
MBRS1100
R10
18Ω
V
IN
R1
24k
C1
22µF
R14
820k
R15
33k
R9
51Ω
R5
51k
R4
3.01k
1%
R3
34.0k
1%
C8
0.1µF
+
C4
150µF
D1
MBRD660
D5
BAS16
+
C9
470pF
C3
100pF
C2
1.5µF
×3
8
5
9
4
1
12
2
11
10
3
6
7
C5
1µF
R13
750Ω
1W
C10
100pF
•
••
•
•
•
PGND
I
SENSE
GATE
V
C
FB
V
CC
UVLO3V
OUT
SGNDR
CMPC
R
OCMP
MENAB
LT1725
ENDLYSFSTOSCAP t
ON
VERSA-PAK is a trademark of Coiltronics, Inc
TELECOM 48V TO ISOLATED 15V APPLICATION
The design in Figure 9 accepts an input voltage in the
range of 36V to 72V and outputs an isolated 15V at up to
2A. Transformer T1 is an off-the-shelf VERSA-PAK
TM
#VP5-0155, produced by Coiltronics. As manufactured, it
consists of six ideally identical independent windings. In
this application, three windings are stacked in series on
the primary side and two are placed in parallel on the
secondary side. This arrangement provides a 3:1 primary-
to-secondary turns ratio while maximizing overall effi-
ciency. The remaining winding provides a primary-side
ground-referred version of the flyback voltage waveform
for both feedback information and providing power to the
LT1725 itself.
Capacitor C7 sets the switching frequency at approxi-
mately 200kHz. Optimal load compensation for the trans-
former and secondary circuit components is set by resistor
R8. Output voltage regulation and overall efficiency are
shown in the accompanying graphs. The resistor divider
formed by R14 and R15 sets the undervoltage lockout
threshold at about 32V, with a hysteresis band of about 2V.
The soft-start and 3V
OUT
features are unused as shown.
23
LT1725
1725fa
TYPICAL APPLICATIO S
U
I
LOAD
(A)
0
V
OUT
(V)
15.0
2.0
1725 F09b
14.5
0.5
1.0
1.5
2.5
15.5
V
IN
= 36V
V
IN
= 72V
V
IN
= 48V
Application Regulation Application Efficiency
I
LOAD
(A)
0.01
60
EFFICIENCY (%)
70
80
90
0.1 1 10
1725 F09c
50
40
30
20
V
IN
= 48V
V
OUT
= 15V
48V to Isolated 15V Application Parts List
T1: Coiltronics VP5-0155 VERSA-PAK
M1: International Rectifier IRF620. 200V, 0.8Ω N-channel
MOSFET
D1: Motorola MBRD660. 6A, 60V Schottky diode
D2: Motorola MBRS1100. 1A, 100V Schottky diode
D3, D4: 1N5257. 33V, 500mW Zener diode
D5: BAS16. 75V rectifier diode
C1: AVX TPSD226M025R0200. 22µF, 25V tantalum
capacitor
C2a, C2b, C2c: Vishay/Vitramon VJ1825Y155MXB. 1.5µF,
100V X7R ceramic capacitor
C3: 100pF, 100V, X7R ceramic capacitor
C4: Sanyo 20SV150M. 150µF, 20V, OS-CON electrolytic
capacitor
C5: 1µF, 25V, Z5U ceramic capacitor
C6: 1nF, 25V, X7R ceramic capacitor
C7: 47pF, 25V NPO/COG ceramic capacitor
C8: 0.1µF, 25V, Z5U ceramic capacitor
C9: 470pF, 25V, X7R ceramic capacitor
C10: 100pF, 25V, X7R ceramic capacitor
R1: 24k, 1/4W, 5% resistor
R2: IRC LR2010. 0.1Ω, 1/2W current sense resistor
R3: 34.0k, 1% resistor
R4: 3.01k, 1% resistor
R5, R6, R7: 51k, 5% resistor
R8: 6.2k, 5% resistor
R9: 51Ω, 5% resistor
R10: 18Ω, 5% resistor
R11: 150Ω, 1/4W, 5% resistor
R12: 5.1Ω, 5% resistor
R13a, R13b: 1.5k, 1/2W, 5% resistor
R14: 820k, 5% resistor
R15: 33k, 5% resistor
24
LT1725
1725fa
TYPICAL APPLICATIO S
U
TELECOM 48V TO ISOLATED 5V APPLICATION
The design in Figure 10 accepts an input voltage in the
range of 36V to 72V and outputs an isolated 5V at up to 2A.
Transformer T1 is available as a Coiltronics CTX02-14989.
Capacitor C7 sets the switching frequency at approxi-
mately 275kHz. Optimal load compensation for the trans-
former and secondary circuit components is set by resistor
R8. Output voltage regulation and overall efficiency are
shown in the accompanying graphs. Efficiency is shown
both with and without the R11 preload. The resistor divider
formed by R13 and R14 sets the undervoltage lockout
threshold at about 32V, with a hysteresis band of about 2V.
The soft-start and 3V
OUT
features are unused as shown.
R2
0.18Ω
M1
IRF620
T1
CTX02-14989
V
OUT
5V
1725 F10a
R7
51k
R6
51k
C7
47pF
6314
109
8
7
13 12 4 5
15
11 1
2
16
C6
1nF
R8
2.7k
R12
68Ω
R1
47k
V
IN
R10
22Ω
R13
820k
R14
33k
R5
51k
R4
3.01k
1%
R3
35.7k
1%
C8
0.1µF
+
C3
150µF
D1
12CWQ06
R9
18Ω
C5
470pF
D2
BAS16
+
C4
150pF
C2
1.5µF
C1
15µF
4
2
11
9
12
10
1
6
R11
51Ω
1W
C9
100pF
C10
1µF
PGND
I
SENSE
GATE
V
C
FB
V
CC
UVLO3V
OUT
SGNDR
CMPC
R
OCMP
MENAB
LT1725
ENDLYSFSTOSCAP t
ON
Figure 10. 48V to Isolated 5V Converter
I
LOAD
(A)
0
V
OUT
(V)
5.00
1725 F10b
4.75
0.5
1.0
1.5
2.0
5.25
V
IN
= 36V
V
IN
= 72V
V
IN
= 48V
I
LOAD
(A)
0.01
60
EFFICIENCY (%)
70
80
90
0.1 1 10
1725 F10c
50
40
30
20
V
IN
= 48V
WITHOUT R11
PRELOAD
WITH R11
PRELOAD
Application Regulation Application Efficiency
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28

LT1725IGN#PBF

Mfr. #:
Buy LT1725IGN#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators General Purpose Iso Fly Cntr
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet