DN06008-D
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Transcript of DN06008-D
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Design Note DN06008/D
+/- 18 V, Dual Output Power Supply
Device Application Input Voltage Output Power Topology I/O Isolation
NCP1308Audio Amp Power
Supply +/-18V90 to 270 Vac 45 W, 90 W peak
QuasiResonantFlyback
Yes
Circuit Description
A low cost 45 watt nominal, 90 watt peak, dual +/- 18 voltoutput power supply is presented here for poweringaudio amplifiers or similar applications. Because the sumof the outputs are sensed, good voltage regulation andtracking is provided despite the extremely simple zenerand optocoupler voltage feedback circuit. The off-linepower converter is implemented utilizing ONs NCP1218quasi-resonant (QR) flyback controller. This topologyprovides very high conversion efficiency and low noisegeneration because of the QR, zero voltage switching
properties and the fact that the flyback switchingoperation is achieved in the discontinuous inductorcurrent, critical conduction mode. The input circuitfeatures common and differential mode conducted EMIfiltering using off-the-shelf components. An auxiliary Vccwinding on the flyback transformer also provides for verylow input standby power (less than 1 W) under no loadconditions.
Key Features
Dual, tracking +/- 18 volt outputs.Very low cost, simple off-line power supply circuit.Quasi-resonant, critical conduction mode flyback
topology for maximum efficiency.Input conducted EMI filter.Low output ripple (< 100 mV)NTC thermistor inrush limitingVery low EMI noise generationInherent over-current and over-voltage protection
Other SpecificationsOutput 1 Output 2 Output 3 Output 4
Output Voltage +18 V - 18 V N/A N/A
Ripple
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Schematic
100uF25V
NOTES:
1. Crossed lines on schematic are NOT connected.2. Q1 is Infineon SP8N80C3 (8 amp, 800 volt)3. U2 is Vishay H11A817A or equivalent optocoupler.4. TH1 is NTC thermistor for inrush limiting.5. L1 is Coilcraft BU15-7521R0BL EMI inductor.6. L2 & L3 are Coilcraft PCV-0-472-05L (4.5uH, 5A)7. Q1 will need a small heatsink.8. BD1 can be 4 - 1N4005 rectifiers (ON Semi).9. D1, D2, D3, D4, U1 are ON Semiconductor components10. Output caps are radial lead, low impedance types (UCC LXV series or similar).11. See drawing for T1 details. Suggested proto vendor is Mesa Power Systems, Escondido, CA (800-515-8514)
C5
T
F1
1Meg0.5W
C1
1
2 34
5 68
14
3
NCP1308
TH1
L1
T1
C2
C3 C4
C6
13
C8C9
C18
Q1
R1
D1
D3
D4
U1
U2
R2
R3
R4R5R6
R7
R8
R9
R12
OptionalChassisGnd
Gnd
AC Input
+18V
Com
-18V
BD1
C10
L2
L3
C11 C12
C13 C14
C15 C16
C19
C17
270pF2kV
10K4.7
0.271W
15K
27K
1K
100
1nF47uF16V 100pF
2A250Vac
10 ohm1.5A
2.2nF"Y2"x 2
0.22uF"X2"
0.22uF"X2"
ChassisGnd 100uF
25V2.7K
0.1uF50V
0.1uF50V
0.11N4148
2,200uF25V x 2
2,200uF25V x 2
MBR1100
MBR1100
4.7uH
4.7uH
90 Watt Peak, Dual Output Quasi-Resonant Power SupplyON Semiconductor Design Center
1
C7
11
3
6
7
4
9
2
220
68
10nF
1N5258B(36V)
220uF400V
120,5W
D2
R10
R11
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MAGNETICS DESIGN DATA SHEET
Part Description: Quasi-resonant flyback transformer, 100W pk , 2 output
Project : Dual output +/-18V, 45 watt (90 W peak) audio amplifier power supply
Schematic ID:
Core Type: ETD29 (Ferroxcube 3C90 material or equivalent)
Core Gap: Gap for 400 uH +/- 5%
Inductance: 380 to 420 uH nominal across primary (pins 13 to 1)
Bobbin Type: ETD 13 pin horizontal pc mount (Ferroxcube PC1-29H)
Windings (in order):
Winding # / type Turns / Material / Gauge / Insulation Data
Hipot: 2.7 kV primary/aux to all secondaries. Vacuum varnish.
Schematic Lead Breakout / Pinout
T1
Aux winding (11 - 3) 7 turns of # 24HN spiral wound evenly over primary. Self-leads to pins. Insulate for 1 kV to next winding.
Primary (13 - 1) 63 turns of #30HN over one layer; cuff ends with tape; Self-leads to pins; insulate for 3 kV to next layer.
+/- 18V secondary (9 - 4, 7 - 6) 10 turns bifilar (2 strands) of #26HN with 1 strand a different color, flat wound over 1 layer with 0.20" end margins. Self-leads to pins with similar colors to same
pin (see drawing below).
Bottom (pin side) view
Pri
Aux
13
1
11
3
9
47
6
+18V
-18V
1 2 3 4 5 6
13 12 11 10 9 8 7
BifilarWound
1 2006 ON Semiconductor.
Disclaimer: ON Semiconductor is providing this design note AS IS and does not assume any liability arising from its use; nordoes ON Semiconductor convey any license to its or any third partys intellectual property rights. This document is provided only toassist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associatedwith its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of itsproducts at any time, without notice.
Design note created by: Frank Cathell, e-mail: [email protected]
