PI-1768-020596
2.6 in.
0.8 in.
1.4 in.
RD2
85 to 132 VAC or 170 to 265 VAC Input,
8W(10W Peak) Output
Product Highlights
Low Cost Production Worthy Reference Design
Only 21 components!
Single sided board
Low cost thru-hole components
Fully assembled and tested
Easy to evaluate and modify
Extensive performance data
Up to 77% efficiency
Light weight - no heat sink required for TOPSwitch
Fully Protected by
TOPSwitch
Primary safety current limit
Output short circuit protection
Thermal shutdown protects entire power supply
Designed for World Wide Operation
Designed for IEC/UL safety requirements
Meets VDE Class B EMI specifications
Typical Applications
Replacement for low power linear adapters
Auxiliary power supply for appliance, motor control,
utility meters, smart building, UPS, etc.
Description
The RD2 reference design board is an example of a very low
cost production worthy power supply design using the
TOPSwitch family of Three-terminal Off-line Switchers from
Power Integrations. It is intended to help TOPSwitch users to
quickly develop their products by providing a basic design that
can be easily modified to fit a particular application. In most
cases, a minor change to the transformer for a different output
voltage or voltages is all that is needed. A complete set of
performance curves, the parts list, the board layout and details
on transformer design are provided to speed up the TOPSwitch
based switcher design.
May 1996
TOPSwitch
Reference Design Board
85 to 132 VAC
o
or 170 to 265 VAC
VDE B
(VFG243 B)
CISPR22
Figure 2. Table of Key Electrical Parameters.
PARAMETER
LIMITS
Input Voltage Range
Input Frequency Range
47 to 440 Hz
Temperature Range
0 to 70
C
Output Voltage
(I = 0.67A)
12 V
10%
Output Power
(continuous)
8 W
Output Power
(peak)
10 W
Line Regulation
0.7%
Load Regulation
(10%-100%)
5%
Efficiency
(115 V input, 8 W out)
75%
Output Ripple Voltage
50 mV MAX
Safety
IEC 950 / UL1950
EMI
(85-132 VAC)
(170-265 VAC)
Figure 1. RD2 Board Overall Physical Dimensions.
85 to 132 VAC
RD2
B
5/96
2
Figure 3. Schematic Diagram of the RD2 Power Supply.
Figure 4. Component Legend of the RD2.
D
C
S
S
TOP
210
PI-1783-020596
VR1
BZY97-C200
D1
UF4005
R1
6.8
3.3
H
RA
470 K
JP1*
JUMPER
BR1
DF06M
C1
10
F
200 V
R2
390
1W
L1
F1
2A
T1
T1RD2
U1
1
3
+
+
+
+
+
+
-
2
4
8
D2
MBR360
5
L2
8 mH
0.2A
C6
47nF
250VAC
X2
C7
1nF
250 VAC
Y1
* JPI CLOSED FOR 115 VAC INPUT
JPI OPEN FOR 230 VAC INPUT
C5
47
F
10 V
D3
1N4148
C3
120
F
16 V
C2
330
F
16 V
C9
10
F
200 V
12 V
RTN
J1
L
N
RB
470 K
PI-1817-040296
L2
VR1
-
BR1
-
+
+
L1
+
RA
RB
U1
D1
D2
C2
R2
R1
D3 T1
C7 C3
+
+
+
+
-
C5
JP1
C6
F1
C1
C9
8
N
L
TOPSwitch RD2
CAUTION
The RD2 features a 115/230 VAC selectable input, and is shipped configured for 230 VAC operation (JP1 open).
If JP1 is used for 115 VAC operation, it must be removed before applying 230 VAC.
B
5/96
RD2
3
Component Listing
Reference
Value
Part Number
Manufacturer
U1
TOP210PFI
Power Integrations
D1
600V, 1A, UFR
UF4005
General Instruments
D2
Schottky, 3A, 60V
MBR360
Motorola
D3
75 V Switching
1N4148
Rohm
BR1
1 A, 600 V
DF06M
General Instruments
VR1
200 V Zener, 1.5 W
BZY97-C200
SGS/Thomson, Fagor
L1
3.3
H, 4A
Custom
L2
8 mH, 0.2A
SU9V-02080
Tokin
C1, C9
10
F, 200V
KMG200VB10RM10X16
United Chemicon
C2
330
F, 16V
LXF16VB331M8X15
United Chemicon
C3
120
F, 16V
LXF16VB121M6.3X11.5
United Chemicon
C5
47
F, 10V
KME10VB47RM5X12.5
United Chemicon
C6
47 nF, 250 VAC, X 2
F1772-347-2000
Roederstein
C7
1 nF, 250 VAC, Y1
DE1110 E 102M ACT4K-KD Murata
RA, RB
470 K, 1/4 W
5043CX470K0J
Philips
R1
6.8
, 1/4 W
5043CX6R800J
Philips
R2
390 ohms, 1 W
MO-1 391J
Koa/Speer
T1
Custom
T1RD2
F1
2A, 250 VAC
19372, 2A
Wickman
General Circuit Description
The RD2 is a low-cost, isolated Buck-Boost or flyback switching
power supply using the TOP210 integrated circuit. The circuit
shown in Figure 3 produces a 12 V, 8 W power supply that
operates from 85 to 132 VAC or 170 to 264 VAC input voltage.
The 12 V output voltage is determined by the TOPSwitch
control pin shunt regulator voltage, the voltage drop of D3, and
the turns ratio between the bias and output windings of T1.
Other output voltages are also possible by adjusting the
transformer turns ratios. R1 and C5 provide filtering of the bias
winding to improve line and load regulation.
AC power is rectified and filtered by BR1, C1 and C9 to create
the high voltage DC bus applied to the primary winding of T1.
The other side of the transformer primary is driven by the
integrated high-voltage MOSFET inside the TOP210. JP1 is
a jumper used to select 115 V or 230 V operation. Adding JP1
selects 115 V operation. Leaving JP1 open selects 230 V
operation. RD2 is supplied with JP1 open. RA and RB equalize
leakage currents between C1 and C9. D1 and VR1 clamp the
leading-edge voltage spike caused by transformer leakage
inductance to a safe value and reduce ringing. The power
secondary winding is rectified and filtered by D2, C2, L1, and
C3 to create the 12 V output voltage. R2 provides a pre-load on
the 12 V output to improve load regulation at light loads. The
bias winding is rectified and filtered by D3, R1, and C5 to create
a bias voltage to the TOP210. Common-mode EMI currents
which flow between the primary windings of the transformer
and the secondary output circuitry are attenuated by L2 and C7.
Differential-mode EMI currents caused by pulsating currents at
the input of the power supply are attenuated by C6 and L2. C5
filters the internal MOSFET gate drive charge current spikes on
the Control pin, determines the auto-restart frequency, and
together with R1, compensates the control loop.
The circuit performance data shown in Figures 6-18 was
measured with AC voltage applied to the RD2.
Load Regulation (Figure 6) - The amount of change in the DC
output voltage for a given change in output current is referred
to as load regulation. The 12 V output stays within
5% from
10% to 100% of rated load current. The TOPSwitch on-chip
overtemperature protection circuit will safely shut down the
power supply under sustained overload conditions.
Figure 5. Parts List for the RD2.
RD2
B
5/96
4
General Circuit Description (cont.)
Figure 6. Load Regulation
Figure 7. Line Regulation
Output Voltage (% of Nominal)
PI-1769-020596
100
100
95
95
105
105
Load Current (mA)
Load Current (mA)
0
100 200 300
VIN = 115 VAC
400 500
600 700
0
100 200 300
VIN = 230 VAC
400 500
600 700
Input Voltage (VAC)
Output Voltage (% of Nominal)
PI-1770-020596
180
200
220
240
260
100
99.5
100
100.5
99
99.5
99
101
101
100.5
Input Voltage (VAC)
90
100
110
120
130
IOUT = 0.17 A
IOUT = 0.67 A
IOUT = 0.17 A
IOUT = 0.67 A
DC bus and 12 V output voltage. Capacitors C1 and C9 charge
to the peak of the AC input voltage before TOPSwitch turns on.
The delay of 150 ms (typical) is caused by the time required to
charge the auto-restart capacitor C5 to 5.7 V. At this point the
power supply turns on as shown.
Figure 13 shows the output voltage turn on transient.
Line frequency ripple voltage is shown in Figure 14 for
115 VAC input and 8W output. Switching frequency ripple
voltage is shown in Figure 15 for the same test condition.
The power supply transient response to a step load change from
0.5 A to 0.67 A (75% to 100%) is shown in Figure 16. Note that
the response is quick and well damped.
The RD2 is designed to meet worldwide safety and EMI
(VDE B) specifications. Measured conducted emissions are
shown in Figure 17 for 115 VAC and Figure 18 for 230 VAC.
Line Regulation (Figure 7) - The amount of change in the DC
output voltage for a given change in the AC input voltage is
called line regulation. The maximum change in output voltage
is less than
0.7%.
Efficiency (Line Dependent) - Efficiency is the ratio of the
output power to the input power. The curves in Figures 8 and 9
show how the efficiency changes with input voltage. Curves
are also given to show the difference in efficiency when C1 and
C9 are changed from 10
F to 22
F.
Efficiency (Load Dependent) - The curves in Figures 10 and 11
show how the efficiency changes with output power at 115 and
230 VAC inputs. The curves also show the increase in efficiency
when C1 and C9 are changed from 10
F to 22
F.
Power Supply Turn On Sequence - The internal switched, high-
voltage current source provides the initial bias current for
TOPSwitch when power is first applied. The waveforms shown
in Figure 12 illustrate the relationship between the high-voltage
B
5/96
RD2
5
PI-1775-020596
0
250
500
Time (ms)
0
5
10
100
0
200
300
15
OUTPUT
VOLTAGE
DC BUS VOLTAGE
Figure 12. Turn On Delay
Figure 13. Output Voltage Turn On Transient
60
1
2
3
5
6
7
8
4
Output Power, (W)
Output Efficiency (%)
PI-1773-020596
70
80
75
65
VIN = 115 VAC
VIN = 115 VAC, C1, C9 = 22
F
Figure 8. Efficiency vs. Input Voltage, 85-132 VAC
Figure 9. Efficiency vs. Input Voltage, 170-265 VAC
60
85
95
105
125
135
115
Input Voltage (VAC)
Output Efficiency (%)
PI-1771-020596
70
80
75
65
IOUT = 0.67 A
IOUT = 0.17 A
IOUT = 0.17 A, C1, C9 = 22
F
IOUT = 0.67 A, C1, C9 = 22
F
60
170
190
210
250
270
230
Input Voltage (VAC)
Output Efficiency (%)
PI-1772-020596
70
80
75
65
IOUT = 0.17 A
IOUT = 0.67 A, C1, C9 = 22
F
IOUT = 0.17 A, C1, C9 = 22
F
IOUT = 0.67 A
Figure 10. Efficiency vs. Output Power, 115 VAC Input
Figure 11. Efficiency vs. Output Power, 230 VAC Input
60
1
2
3
5
6
7
8
4
Output Power (W)
Output Efficiency (%)
PI-1774-020596
70
80
75
65
VIN = 230 VAC
VIN = 230 VAC, C1, C9 = 22
F
PI-1776-020596
0
25
50
Time (ms)
Output Voltage (V)
0
2
4
10
8
12
6
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