Design Idea DI-39
®
TOPSwitch-GX
13 W, Universal
Input DVD Supply with 70 mW No-load
Application
DVD
Device
TOP244P
Power Output
13 W (17 W pk)
Input Voltage
85-265 VAC
Output Voltage
3.3 V / 5 V / 12 V / -12 V
Topology
Flyback
®
Design Highlights
•
•
•
•
•
•
•
High efficiency multi-ouptut flyback (77% minimum)
Topology scalable to higher powers
Excellent cross-regulation
Excellent input no-load consumption <70 mW input
132 kHz switching frequency allows smaller transformer
Frequency jitter eliminates common-mode EMI choke
>10 dB margin against CISPR22-B conducted EMI with
artificial hand grounding
The supply operates at full frequency at high and medium
power and reduces frequency at light loads. Components D9
and C10 rectify and filter the bias voltage.
TOPSwitch-GX
frequency jitter allows conducted EMI
compliance without a common-mode choke, using only
capacitors C1, C4 and inductor L1 as an EMI filter.
Components D5 and C2 form a capacitor clamp circuit
absorbing leakage inductance energy during normal operation.
Zener VR1 clamps the voltage to a safe level during abnormal
and transient conditions. After clamping, reverse current
flows through D5, recovering some of the energy. Resistor
R5 limits the reverse current and, with R7, improves EMI by
limiting the ringing on the drain. Continuous mode operation
allows reduced primary and secondary peak currents,
optimizing cross regulation and load regulation by
minimizing leakage inductance induced voltage shifts.
Resistors R15 and R16 share the feedback from the 3.3 V
and 5 V outputs for good cross-regulation.
L2
3.3
µH
Operation
The
TOPSwitch-GX
uses current mode feedback to achieve
excellent no-load standby. Components C16, R1 and Q2 provide
a constant current powering the
TOPSwitch-GX
CONTROL
pin. Resistor R2 feeds the remainder of Q2 current to the M pin,
reducing
TOPSwitch-GX
current limit with increased current.
Resistor R11 sets the maximum current limit of the device.
Components R6, Q1 and C13 implement slope compensation.
C8
1 nF
Y1
D1-D4
1N4005
F1
3.15 A
250 VAC
85 - 265
VAC
C3
0.047
µF
x2
C1
33
µF
400V
VR1
P6KE180
C4
33
µF
400V
R7
100
Ω
C2
0.01
µF
1 KV
R5
47
Ω
D5
1N4007
D7
UF4003
12 V, 400 mA
C20
150
µF
25 V
C15
470
µF
25 V
L3
3.3
µH
L4
3.3
µH
R9
200
Ω
U2B
PC817
R8
1 kΩ
R16
6.34 kΩ
C17
470
µF
10 V
5 V, 1.6 A
C11
D11
1800
µF
1N5822
25 V
D10
1N5822
D8
UF4003
C12
1000
µF
10 V
C9
220
µF
25 V
C6
220
µF
25 V
R12
1 1/2 W
PC817
U2A
3.3 V, 700 mA
C18
470
µF
10 V
RTN
R15
20 kΩ
C14
0.1
µF
R1
270
Ω
TOPSwitch-GX
U1
TOP244P
R2
20 kΩ
D
M
CONTROL
C
R10
3.3 kΩ
C16
0.33
µF
R6
20 kΩ
C7
10
µF
50 V
U3
TL431CLP
R13
10 kΩ
Q2
2N3906
Q1
2N3906
- 12 V, 100 mA
D9
C10 1N4148
47
µF
50 V
R11
7.5 kΩ
L1
1.4
µH
0.5 A
S
C13
47 pF
R14
6.8
Ω
C5
47
µF
10 V
C19
0.1
µF
PI-3321-111902
Figure 1. TOPSwitch-GX DVD Player Schematic.
.
DI-39
www.powerint.com
November 2002
POWERINT [ POWER INTEGRATIONS, INC. ]
