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

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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Test results AN1735

2.2 Efficiency results

Figure 6. Efficiency vs. P

OUT

The typical efficiency of the board is about 75%. The efficiency measurements are taken at a nominal input voltage of 120 V

. 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

at the

maximum output power rating of 10W. The average measured efficiency is 75%.

Figure 7. Efficiency vs. V

2.3 Load response

At an input voltage of 120 VAC, 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.

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AN1735 Test results

Figure 8. Transient load response

2.4 Line and load regulation

The output voltages are measured over the entire input voltage range, that is between 90 and 264 V graph, the output voltage remained at a constant +12V output. The line regulation therefore is 0%.

Figure 9. Line regulation

. This gives the line regulation as shown in Figure 9. As can be seen from the

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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 from 10% to 100% of full load on the output.

Figure 10. Load regulation

. The load regulation is approximately 0.125% when tested

2.5 EMI emissions

Figure 11. EMI conducted emissions

The results shown in Figure 11 indicate that the unit passes EN55022 Class B EMI conducted emission tests.

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AN1735 Waveforms

3 Waveforms

Figure 12 shows the drain current (I

)and drain voltage (VDS) during normal operation

DRAIN

at full load. The converter works in the Discontinuous mode as illustrated by the waveforms.

Figure 12. V

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 Tab l e 2.

Table 2. Changes in output voltage and current

out

5.0V 2.0A CVP32-006 2.49KΩ 1% 2.49KΩ 1% 2x1000µF/25V 100µF/25V

12V 0.84A CVP32-001 13.3KΩ 1% 3.48KΩ 1% 1000µF/25V 100µF/25V

15V 0.67A CVP32-005 14.7KΩ 1% 2.94KΩ 1% 680µF/35V 100µF/35V

24V 0.42A CVP32-007 13.0KΩ 1% 1.50KΩ 1% 220µF/50V 100µF/50V

T1 R8 R5 C9 C10

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Thermal considerations AN1735

5 Thermal considerations

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.

6 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. Ta b le 3 lists the input power consumption (P input voltages when measured with zero loads at the output.

Table 3. Input power consumption in No-Load conditions

) values at different

Input voltage Input Wattage at No Load

115 V

230 V

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

input supply.

Therefore, the reference board complies with the Blue Angel standard.

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AN1735 Transformer specifications

7 Transformer specifications

Figure 13. Mechanical drawings of the transformer

The transformer is designed and manufactured by Cramer Coil and Transformer Co.

Tab le 4 lists the electrical characteristics of the transformer.

Table 4. Electrical characteristics of the transformer

Parameter Values

Primary inductance 2.25mH

Primary leakage inductance 19.9µH typical

HIPOT (N1, N3, N4 to N2) 5500VAC, 1Sec

DCR (N1/N4) 2.87

DCR (N2) 0.07Ω typical

DCR (N3) 1.26Ω typical

Turns ratio (N1/N4:N2) 1:0.127

Turns ratio (N1/N4:N3) 1:0.167

± 10%

Ω typical

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

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Component list AN1735

8 Component list

Table 5. Component list

Quantity Reference Description

1 BR1 KBP210GDI

1 C1 0.047µF/250V boxcap

1C222µF/400V electrolytic

1 C3 100pF 1kV ceramic

1C422µF/25V electrolytic

1C60.01µF/50V ceramic

1 C8 4.7nF/250V Y cap

1 C9 1500µF/25V electrolytic

1 C10 100µF/25V electrolytic

1 C11 0.01µF/50V ceramic

1 C12 10µF/400V electrolytic

1D11N4148

1 D2 STMicroelectronics BYW98-200

1F10.5A Fuse

2 J1, J2 Connectors

1 L1 2x30mH common-mode line choke

1 L2 Coilcraft 10µH inductor

1R150Ω 5% 1W wire wound

1R22KΩ 5% 1/2W

1R468Ω 5% 1/4W

1 R5 3.48KΩ 1% 1/4W

1 R6 470Ω 5% 1/4W

1R79.1kΩ 5% 1/4W

1 R8 13.3KΩ 1% 1/4W

1 T1 Cramer coil transformer CVP32-001

1 U1 STMicroelectronics VIPer22A

1 U2 H11A817A or LTV817 optocoupler

1 U3 STMicroelectronics TL431

1 W1, W2 Jumper wire

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AN1735 Component list

Figure 14. Schematic diagram

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Revision history AN1735

9 Revision history

Table 6. Revision history

Date Revision Changes

Jul-2003 1 Initial release.

17-Jul-2006 2 Converted to new corporate template. Minor editing changes.

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AN1735

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