ST AN1735 Application note

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

Contents AN1735

Contents

1 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1 Board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 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

3 Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

4 Output current and voltage capability . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6 Blue angel standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

7 Transformer specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8 Component list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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AN1735 Summary description

1 Summary description

Tab le 1 lists the main parameters of the converter while a prototype of the board is shown in
Figure 1.

Table 1. Operating conditions

Parameter Limits

Input voltage range 90 to 264 V

Input frequency range 50/60 Hz

Output Voltage V=12V

Output current I=0.84A

Output power 10W

Efficiency 75% typical

Line regulation ± 0%

Load regulation ± 0.2%

Output voltage ripple 20m V

EMI EN55022 class B

AC

PP

Figure 1. Board prototype

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Summary description AN1735

1.1 Board layout

Figure 2. Board top legend (not to scale)

Figure 3. Board bottom foil (not to scale)

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AN1735 Test results

2 Test results

2.1 Frequency ripple

Figure 4 presents the line frequency ripple taken with an input voltage of 90 VAC. A 10mVPP

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

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