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

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	Limits
Input voltage range		90 to 264 VAC
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 VPP
EMI		EN55022 class B
Figure 1.	Board prototype

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Summary description	AN1735

1.1Board 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

2.1Frequency 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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