DI-35 Просмотр технического описания (PDF) - Power Integrations, Inc
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DI-35 Datasheet PDF : 2 Pages
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Design Idea DI-35
TOPSwitch-®GX
16 W Audio Amplifier Power Supply
Application
Audio Amplifier
Device
TOP245P
Power Output Input Voltage
16 W (35 W Peak) 85-265 VAC
Output Voltage
16 V
Topology
Flyback
Design Highlights
The EMI filter has been significantly simplified to three
• No heatsinks required!
• 77% efficiency (min), at 85 VAC input/35 W output
components (L1, CX1 and CY1), thanks to the built-in
frequency jitter function of the TOPSwitch-GX family.
• Low no-load input power: < 0.7 W at 230 VAC input
• Low component count: 37, excluding I/O connectors
• Stable operation with or without 10,000 µF output buffer
capacitor
• Robust transformer design enables 35 W peak power
• Meets CISPR22B EMI with >10 dB of margin
The RCD network of C4, R3, R4, and D5 limits (clamps) the
peak voltage that the U1-DRAIN sees. A glass-passivated
normal recovery diode (D5) recycles stored leakage energy,
increasing overall efficiency. DRAIN ringing is dampened by
R4 (necessary when a normal recovery diode is used).
• Ideal for both class AB and class D audio amplifiers,
6 channel Dolby Digital with 6 ohm speakers
The bias winding provides operating power and feedback
current to the CONTROL pin of U1. The U2-LED, R8 and
Operation
VR1 comprise the feedback circuit that senses the output
voltage. The current through the U2-LED regulates the output
Many of the built-in TOPSwitch-GX features have been used
to reduce the component count, transformer size and overall
voltage by modulating the feedback current that flows into
the CONTROL pin of U1.
cost of this universal input flyback power supply. Designed
around a TOP245P (DIP-8 package), the device uses PCB
Key Design Points
copper for its heatsink, eliminating the costs of both a heatsink
and the installation labor. Output diode D7 is also cooled the
same way.
• Ensure that the control loop has enough phase margin at
the extremes of the rated input voltage and output load,
both with and without the output buffer capacitor.
Resistors R1 and R2 set the nominal under-voltage (UV)
lockout and overvoltage (OV) shutdown limits to 84 V and
378 V, respectively. UV lockout protects the supply from
overheating at low line and eliminates power-up and power-
• A 5% VR1 should be acceptable for an audio amplifier.
Greater accuracy will require a 2% VR1.
• OV and UV thresholds are determined by:
VOV = 225 µA • (R1+R2) and VUV = 50 µA • (R1+R2).
down glitches.
line surges.
OV shutdown protects the power supply from
CY1
R6 C6
2.2 nF
33 Ω 470 pF
R3 C4
(Safety)
1/4 W 100 V
200 kΩ 1 nF
D1-D4
1/2 W 1 kV
1
9,10
1N4007
C1
100 µF
R1
1 MΩ
D7
3
6,7
SB5100
400 V
R7
C7 C8
L1
6.8 mH
0.8 A
R2
1 MΩ
R4
33 Ω
1/4 W
D5
1N4007G
4 10 Ω
5
T1
D6
BAV20
470 µF 470 µF
25 V 25 V
C5
1 µF
50 V
TOPSwitch-GX
CX1
220 nF
250 VAC
D
M
U1
CONTROL TOP245P
C
U2
PC817A
L2
3.3 µH
C9
100 µF
25 V
16 V, 1 A /
2.2 A
R8
150 Ω
R10
1k
RTN
F1
3.15 A
250 V
85-265
L VAC N
S
C2
100 nF
50 V
R5
3.3 Ω
C3
100 µF
16 V
VR1
IN5244B
5%
C10
47 µF
25 V
Figure 1. Audio Amplifier Power Supply.
PI-3731-070704
DI-35
www.powerint.com
July 2004
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