AN1735
Application note
VIPer22A Single Output Reference Board
90 to 264 VAC input, 10W output
Introduction
This Application Note deals with an off-line wide range single output power supply using a
VIPer22A off-line SMPS primary switcher manufactured by STMicroelectronics. The
VIPer22A combines a dedicated current mode PWM controller with a high voltage Power
MOSFET on the same silicon chip and its switching frequency is internally fixed at 60 kHz.
The feedback path of the power supply includes an optocoupler for secondary regulation and galvanic isolation between primary and secondary sides. The output voltage is regulated at 12V with a maximum output current of 0.84A, resulting in a maximum output power of 10W.
Product highlights
– Switch mode General Purpose Power Supply
– Single-sided Board
– 75% Typical Efficiency
– Output Short Circuit Protection
– Thermal Shutdown Protection
– Complies with EN55022 Class B EMI specifications
– Complies with Blue Angel standards
July 2006 Rev 2 1/15
www.st.com
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Contents
Contents
1
2
AN1735
Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1
Board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1
Frequency ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2
Efficiency results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3
Load response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4
Line and load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.5
EMI emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Output current and voltage capability . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Blue angel standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Transformer specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Component list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2/15
AN1735 Summary description
Table 1
lists the main parameters of the converter while a prototype of the board is shown in
Figure 1
.
Table 1.
Operating conditions
Parameter
Input voltage range
Input frequency range
Output Voltage
Output current
Output power
Efficiency
Line regulation
Load regulation
Output voltage ripple
EMI
Limits
90 to 264 V
AC
50/60 Hz
V=12V
I=0.84A
10W
75% typical
± 0%
± 0.2%
20m V
PP
EN55022 class B
Figure 1.
Board prototype
3/15
Summary description
Figure 2.
Board top legend (not to scale)
Figure 3.
Board bottom foil (not to scale)
AN1735
4/15
AN1735 Test results
Figure 4
presents the line frequency ripple taken with an input voltage of 90 V
AC
. A 10mV
PP
amplitude is measured at the output.
Figure 5
shows the switching ripple on the output at the full load of 0.84A.
Figure 4.
Line frequency ripple
Figure 5.
Switching frequency ripple
5/15
Test results
Figure 6.
Efficiency vs. P
OUT
AN1735
The typical efficiency of the board is about 75%. The efficiency measurements are taken at a nominal input voltage of 120 V
AC
.
Figure 6
shows the efficiency measurements that are taken when the output power is varied from 1W to 10W.
Figure 7
meanwhile shows the efficiency measurement taken when the input voltage is varied from 90 to 264 V
AC maximum output power rating of 10W. The average measured efficiency is 75%.
at the
Figure 7.
Efficiency vs. V
IN
6/15
At an input voltage of 120 V
AC
, the output load is stepped from 50% to 100% load (0.42A to
0.84A). The settling time is found to be 400µs and the dynamic regulation is 120mV or 1%.
The resulting waveforms are shown in
Figure 8
.
AN1735
Figure 8.
Transient load response
Test results
2.4 Line and load regulation
The output voltages are measured over the entire input voltage range, that is between 90 and 264 V
AC
. This gives the line regulation as shown in
Figure 9
. As can be seen from the graph, the output voltage remained at a constant +12V output. The line regulation therefore is 0%.
Figure 9.
Line regulation
7/15
Test results AN1735
The output voltage has also been measured in a range of loads, as shown in
Figure 10
at a
nominal input voltage of 120 V
AC
. The load regulation is approximately 0.125% when tested from 10% to 100% of full load on the output.
Figure 10.
Load regulation
Figure 11.
EMI conducted emissions
8/15
The results shown in
Figure 11
indicate that the unit passes EN55022 Class B EMI
conducted emission tests.
AN1735
3 Waveforms
Waveforms
Figure 12
shows the drain current (I
DRAIN
)and drain voltage (V
DS
) during normal operation at full load. The converter works in the Discontinuous mode as illustrated by the waveforms.
Figure 12.
V
DS
and drain current
4 Output current and voltage capability
The output voltage and current can be set to a different value by changing components as shown in
Table 2
.
Table 2.
V out
5.0V 2.0A
12V 0.84A
15V 0.67A
24V 0.42A
Changes in output voltage and current
T1
CVP32-006
CVP32-001
CVP32-005
CVP32-007
R8
2.49K
Ω 1%
13.3K
Ω 1%
14.7K
Ω 1%
13.0K
Ω 1%
R5 C9
2.49K
Ω 1%
2x1000
µF/25V
3.48K
Ω 1%
2.94K
Ω 1%
1.50K
Ω 1%
1000
680
220
µF/25V
µF/35V
µF/50V
C10
100
µF/25V
100
µF/25V
100
µF/35V
100
µF/50V
9/15
Thermal considerations AN1735
6
The VIPer22A is a single-sided reference board that uses a wide two-ounce copper pad area to act as a heat sink for the VIPer22ADIP. All other traces use one-ounce copper.
At 65° C, the measured case temperature is 90° C, therefore making the junction temperature 123.7° C.
Blue angel standard
The Blue Angel standard is a German certification for products and services that have environmentally friendly aspects. It requires that the power supply consumes less than 1W of power when in Standby mode.
The total power consumption of this reference board is less than 1W when working in
Standby Burst mode.
Table 3
lists the input power consumption (P
IN
) values at different input voltages when measured with zero loads at the output.
Table 3.
Input power consumption in No-Load conditions
Input voltage Input Wattage at No Load
115 V
AC
230 V
AC
200 mW
366 mW
In order to keep the total input power to be less than 1W total, a minimum load of 40 mA is needed when using a 120 V
AC
input supply.
Therefore, the reference board complies with the Blue Angel standard.
10/15
AN1735
Figure 13.
Mechanical drawings of the transformer
Transformer specifications
The transformer is designed and manufactured by Cramer Coil and Transformer Co.
Table 4
lists the electrical characteristics of the transformer.
Table 4.
Electrical characteristics of the transformer
Parameter
Primary inductance
Primary leakage inductance
HIPOT (N1, N3, N4 to N2)
DCR (N1/N4)
DCR (N2)
DCR (N3)
Turns ratio (N1/N4:N2)
Turns ratio (N1/N4:N3)
Values
2.25mH
± 10%
19.9
µH typical
5500VAC, 1Sec
2.87
Ω typical
0.07
Ω typical
1.26
Ω typical
1:0.127
1:0.167
When the VIPer22A (U1) is on, energy is stored in the primary winding of transformer (1-2),
TX1. This energy is transferred to the auxiliary winding (3-4), and to the output (5-6) when the VIPer22A is off. The auxiliary winding provides the bias voltage for the VIPer22A at pin 4
(V
DD
).
11/15
Component list
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
Table 5.
Quantity
Component list
Reference
L1
L2
R1
R2
R4
R5
R6
R7
R8
T1
U1
U2
U3
W1, W2
C9
C10
C11
C12
D1
D2
F1
J1, J2
C3
C4
C6
C8
BR1
C1
C2
Description
KBP210GDI
0.047
µF/250V boxcap
22
µF/400V electrolytic
100pF 1kV ceramic
22
µF/25V electrolytic
0.01
µF/50V ceramic
4.7nF/250V Y cap
1500
µF/25V electrolytic
100
µF/25V electrolytic
0.01
µF/50V ceramic
10
µF/400V electrolytic
1N4148
STMicroelectronics BYW98-200
0.5A Fuse
Connectors
2x30mH common-mode line choke
Coilcraft 10µH inductor
50
Ω 5% 1W wire wound
2K
Ω 5% 1/2W
68
Ω 5% 1/4W
3.48K
Ω 1% 1/4W
470
Ω 5% 1/4W
9.1k
Ω 5% 1/4W
13.3K
Ω 1% 1/4W
Cramer coil transformer CVP32-001
STMicroelectronics VIPer22A
H11A817A or LTV817 optocoupler
STMicroelectronics TL431
Jumper wire
AN1735
12/15
AN1735
Figure 14.
Schematic diagram
Component list
13/15
Revision history AN1735
Table 6.
Date
Jul-2003
17-Jul-2006
Revision history
Revision
1
2
Changes
Initial release.
Converted to new corporate template. Minor editing changes.
14/15
AN1735
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