VIPER22A EQUIVALENT.pdf

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May 2003 1/16

AN1715- APPLICATION NOTE

VIPower: SMPS Solutions for Power LineModem Application with VIPerX2A

F. Cacciotto - F. Gennaro - M. Sciortino

1. ABSTRACT

This application note investigates about possible power supply solutions based on VIPerX2A family,

realized in order to power a Power Line Modem System (PLMS).

As a starting point, the power supplies have been designed and developed according to the

specifications for a complete PLMS based on ST7538 (by STMicroelectronics), but other diffused PLMS

can be suitably supplied.

2. INTRODUCTION

The growth of the automation system in home appliance has brought the development of systems able

to exchange information using the electrical network as a communication medium.

As a result, there is no need to install extra control cable and all the system components can be

connected to the network by plugging them in a wall socket.

These virtual networks also improve the flexibility and the expansibility of the system, since new devices

can be instantly connected to the system by means of a wall socket.

New dedicated modem integrated circuits have been developed in order to make these applications

feasible. A typical PLMS is shown in figure 1.

The Power Line Modem (PLM) is a half duplex asynchronous FSK modem with a carrier frequencycomplying with Europes CENELEC EN50065 standard, which specifies the use of carrier frequencies

from 125kHz to 140kHz for home automation and US FCC regulations, which specifies the use of carrier

frequencies lower than 450kHz.

The Power Line Interface (PLI) connects the PLM to the power lines. It consists in a line driver, which

amplifies the Analog Transmit Output signal (ATO) from the PLM and a line interface, which adapts the

line driver to the power line and insulates the PLMS from the electrical network. Some PLMs directly

integrate the line interface on the chip. The PLI has the following functions:

- TX Mode: amplifies and filters the transmit signal from the ATO;

- RX Mode: provides received signal from power lines to the Receive Analog Input (RAI).

The PLM is connected to a microcontroller or to a Personal Computer (through the RS232 driver

interface), in order to build a home LAN, where each device is able to use any information required

whether it is local (washing machine) or remote (remote control system).

In the previous typical application, the power supply has to be able to provide a single output.

3. VIPerX2A DESCRIPTION

The VIPerX2A family is a range of smart power devices with current mode PWM controller, start-up

circuit and protections integrated in a monolithic chip using VIPower M0 Technology.


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AN1715 - APPLICATION NOTE

Figure 1: Power Line Modem: System configuration

The VIPerX2A family includes:

- VIPer12A, with a 0.4A peak drain current limitation and 730V breakdown voltage;

- VIPer22A, with a 0.7A peak drain current limitation and 730V breakdown voltage.

The switching frequency is internally fixed at 60kHz by the integrated oscillator of the VIPerX2A. The

internal control circuit offers the following benefits:

- Large input voltage range on the VDD pin accommodates changes in auxiliary supply voltage;- Automatic burst mode in low load condition;

- Overtemperature, overcurrent and overvoltage protection with auto-restart.

The internal current mode structure is shown in figure 2.

The feedback pin (FB pin) is sensitive to current and controls the operation of the device. The Power

MOSFET delivers a sense current IS which is proportional to the drain current ID.

R2 receives this current and the current coming from the FB pin. The voltage across R2 is then compared

to a fixed reference voltage of 0.23 V.

+5V Washing

machine

Power

Line Modem

AVCCDVCC

C

+5V

Line interface

Power

Driver

Analog

Front End

+5V LDO

Regulator

Power Line Modem System (PLMS)

Mains

50/60 Hz

+10V

Switch Mode

Power Supply

Remote ControlSystem

PLMS PLMS

+5V Washing

machine

Power

Line Modem

AVCCDVCC

C

+5V

Line interface

Power

Driver

Analog

Front End

+5V LDO

Regulator

Power Line Modem System (PLMS)

Mains

50/60 Hz

+10V

Switch Mode

Power Supply


Mains

50/60 Hz

+10V

Switch Mode

Power Supply


PLMS PLMS


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Figure 2: VIPerX2A current internal structure

The mosfet is switched off when the following condition is reached:

Using the current sense ratio of the mosfet, GID and considering (1), ID is given by:

The FB pin is commonly driven by the emitter of an optocoupler but a discrete BJT or a zener diode can

also be used, behaving as a current source. This current is filtered by a small capacitor C to guarantee

the feedback stability. It is necessary to keep this capacitor very close to the FB pin, to avoid high

frequency instability on the compensation loop.

For low drain currents, (2) applies as long as IFB


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4. POWER SUPPLY DESCRIPTION AND DESIGN

The SMPS specifications are listed in table 1.

Table 1: SMPS specifications.

Due to the low power related to the RX mode, as low as possible switching frequency can be chosen, in

order to have higher order harmonics in the carrier frequency band.

The only way to reduce the switching frequency is to optimise the burst mode operation.

4.1. Clamp Design

The drain voltage needs to be clamped in order to prevent voltage spikes, due to leakage inductance,

from exceeding the breakdown voltage of the device (730V minimum). The most used solution is the

RCD clamp, as shown in figure 3a. This is a very simple and cheap solution, but it impacts on the

efficiency even at no load condition. If the standby efficiency is important, a zener clamp is

recommended, as shown in figure 3b. However such a solution gives higher power dissipation at full

load, even if the clamp voltage is exactly defined.

Figure 3: Clamp circuit topology: (a) RCD clamp and (b) Zener clamp

The capacitor value is calculated in order to charge it with the energy from the leakage inductance and

must ensure that the maximum VSPIKE is never exceeded, thus from energy balance consideration, the

minimum capacitance value is:

Input Voltage 185VAC 265VACVOUT 10V 25%

IOUT(min) 23mA in RX mode

IOUT(max) 480mA in TX mode

(4)

. .

+

Dz

+

R C

D D

RCD CLAMP ZENER CLAMP

(a) (b)

2

R

2

RSPIKE

2

DLIMLK

V)V(V

ILC

+


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In order to have a proper operation of the clamp, the minimum value of resistance is:

Its power rating will be:

For a zener clamp, the zener voltage should be:

with a power capability equal to:

5. APPLICATION DESCRIPTION

In this chapter, two solutions are presented in order to power a typical PLMS in both isolated and non

isolated applications. The first configuration is typical in home automation systems and the last is suitable

for many industrial applications.

The regulation is obtained by means of a zener diode in either solution, considering the high output

voltage tolerance for this application.

The transformer has been designed with lower primary inductance compared to a typical 5W application.

This enables the device to work in burst mode during RX condition, reducing the average switching

frequency.

5.1. Isolated Solution

The first proposed solution regards the isolated Flyback topology with a single input rectifier diode and an

input C-L-C filter. Such a filter provides both DC voltage stabilization and EMI filtering.

In the considered application, the transformer has a secondary winding with galvanic insulation and an

auxiliary winding to supply the VIPer.

In table 2 the transformer specifications are listed and the converter schematic is shown in figure 4.

Table 2: Isolated transformer specifications

(5)

(6)

(7)

(8)

Core geometry E13/7/14Core material N27 or equivalent

BSAT 380mT

Air Gap 0.24mm

Primary Inductance 1.8mH

Leakage Inductance 54HPrimary Winding 166 turns

Auxiliary Winding 52 turns

Output Winding 22 turns

+

R

SPIKESW V

V1lnCf

1

R

SW

2

DLIMLK

2

RR

fIL2

1

R

VP +=

SPIKERZVVV +=

SW

2

DLIMLK

RZ

ZZ

fILVV

V

2

1P

=


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The converter has been tested in several load conditions and in the whole input voltage range, i.e. from

185VAC to 265VAC. Load and line regulation results are shown in figure 5 and figure 6 respectively.

The efficiency measurement has been done using a DC power source and an amperometer, in order to

have a higher accuracy than in AC measurements: the results are shown in figure 7.

In all the considered operating conditions, the converter meets the specifications given in table 1.

Figure 4: Isolated Flyback converter

Figure 5: Load Regulation

+C6470uF

R4220

OPTPC817

DZ18.2V

TF1

C82.2nF-2kV/Y2

+C24.7uF

L1470uH

R1

1.2k+C7

47uF

CONTROLFB

DRAIN

SOURCE

VDD

VIPer12A

R-fuse

10 D4

BYW100-200

R2150k

D3

BAS21

D2STTH106

D1

1N4007C5100pF

+C310uF

C447nF

L222uH

+C14.7uF

GND OUT

AC IN

AC IN

+10V

0 100 200 300 400 500

8.8

9.0

9.2

9.4

9.6

9.8

IOUT

(mA)

VOUT

(V)

185V

220V

265V


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Figure 6: Line Regulation

Figure 7: Efficiency Vs. output current

In figures. 8, 9 and 10 typical waveforms in RX mode and full load are shown: it is important to point out

that, in RX Mode, the converter works in burst mode, limiting the maximum switching frequency to

30kHz.

The startup transient is shown in figure 11. The maximum drain voltage has been measured under worst-

case operations, i.e. start-up at VIN=265VAC and full load.

The maximum measured value is 594V, as shown in figure 11(b) and the output voltage ripple at full load

and VIN=230VAC is shown in figure 12.

180 200 220 240 260 280

8,5

9,0

9,5

10,0

VINAC

(V)

VOUT

(V)

Rx Mode

Full load

0 100 200 300 400 500

40

50

60

70

80

90

100

IOUT

(mA)

Efficiency(%)

185V

230V

265V


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Figure 8: Typical waveforms at 185VAC: (a) RX mode and (b) Full load


Ch1 Freq 29.41kHzCh1 Freq 14.65kHz

Ch1 Max 376V

Ch2 Max 140mA

Ch1 Freq 58.40kHz

Ch1 Max 444V

Ch2 Max 304mA

(a) (b)


Ch1 Max 444V

Ch2 Max 156mA

Ch1 Freq 58.19kHz

Ch1 Max 504V

Ch2 Max 296mA

(a) (b)


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Figure 11: (a) Start up time at 230VAC and (b) VDS during start-up at 265VAC at full load


Ch1 Max 500V

Ch2 Max 164mA

Ch1 Freq 58.22kHz

Ch1 Max 560V

Ch2 Max 296mA

(a) (b)

Ch1 Max 524V

Ch2 Max 17.1V

Ch3 Max 9.2V

Ch1 Freq 59.74kHz

Ch1 Max 594V

(a) (b)

VDD

VOUT

VDS


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Figure 12: Output voltage ripple at 230VAC and full load

5.2. Non Isolated Flyback Description

For non-isolated applications, the following solution can be used.

The transformer specifications are the previous ones, but galvanic insulation and auxiliary winding are

not required. The converter schematic is shown in figure 13.

The VDD voltage is provided rectifying the transformer output voltage. This allows to have a supply

voltage higher of 0.8V (forward voltage drop on D4), avoiding a VDD lower than VDDoff(MAX)=9V.

Figure 13: Non isolated Flyback converter

+C7

47uF

L1470uH

D3STTH106

R2150k

+ C310uF

D21N4148

AC IN

CONTROFB

DRAIN

SOURCE

VDDVIPer12A

GND OUT

D1

1N4007

L2

22uH

C410nF

+ C24.7uF400V

R1

10

DZ19.1V

D4

BYW100-200

+C14.7uF400V

AC IN

C5100pF

R2

1k

TF1

+C6

470uF

+10V


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Load and line regulation results are shown in figures 14 and 15 respectively, while the efficiency is shown

in Figure 16. The converter shows good performance concerning the output voltage regulation, with

efficiency higher than 75% at full load.

Figure 14: Load Regulation

Figure 15: Line Regulation

0 100 200 300 400 500

9,6

9,8

10,0

10,2

10,4

10,6

IOUT

(mA)

VOUT

(V)

185V

220V

265V

180 200 220 240 260 280

9,0

9,5

10,0

10,5

11,0

VINAC

(V)

VO

UT

(V)

Rx Mode

Full load


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Figure 16: Efficiency Vs. output current

In figures 17, 18 and 19 typical waveforms in RX mode and full load are shown: even in this case, in RX

Mode, the converter works in burst mode, with a maximum switching frequency of 30kHz.

The startup transient is shown in figure 20. The maximum drain voltage has been measured under worst-

case operations, i.e. start-up @VIN=265VAC and full load.

The maximum measured value is 612V, as shown in figure 20(b) and the output voltage ripple at full load

and VIN=230VAC is shown in figure 21.

Figure 17: Typical waveforms at 185VAC: (a) RX and (b) Full load

0 100 200 300 400 500

40

50

60

70

80

90

100

IOUT

(mA)

Efficiency(%)

185V

230V

265V


Ch1 Max 380V

Ch2 Max 112mA

Ch1 Freq 58.47kHz

Ch1 Max 454V

Ch2 Max 312mA

(a) (b)


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Ch1 Max 456V

Ch2 Max 128mA

Ch1 Freq 58.23kHz

Ch1 Max 518V

Ch2 Max 304mA

(a) (b)


Ch1 Max 512V

Ch2 Max 128mA

Ch1 Freq 58.11kHz

Ch1 Max 570V

Ch2 Max 304mA

(a) (b)


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Figure 20: (a) Start up time at 230VAC and (b) VDS during start-up at 265VAC at full load

Figure 21: Output voltage ripple at 230VAC and full load

7. SPECTRUM FREQUENCY COMPARISON

If lower switching frequency is required during RX mode due to interference issues, the primary

inductance of the transformer has to be reduced down to 800H, resulting in a higher drain peak current.This imposes a higher drain current capability device such as the VIPer22A, whose minimum peak drain

current is of 560mA.

In figure 22 the comparison between the solutions with VIPer12A and VIPer22A is shown: it is important

Ch1 Max 548V

Ch2 Max 15.2V

Ch3 Max 10.3V

Ch1 Freq 60.11kHz

Ch1 Max 612V

(a) (b)

VDD

VOUT

VDS


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to point out that, due to the lower primary inductance, the converter with VIPer22A in burst mode works

with a lower average switching frequency respect to the solution using VIPer12A, but with a higher peak

drain current.

The harmonic current spectra for the two converters are shown in figure 23 and 24 respectively.

It is possible to note that, in the frequency range up to 200kHz, the current harmonics amplitudes in the

VIPer22A converter are lower than VIPer12A converter. This can give less interference issues when the

PLMS works in RX mode.

Figure 22: Typical waveforms at 185VAC in RX Mode: (a) with VIPer12A and (b) with VIPer22A

Figure 23: Harmonic current spectrum with VIPer12A


Ch1 Max 380V

Ch2 Max 112mA

Ch1

Freq 14.79kHz

Ch1 Freq 19.70kHz

Ch1 Max 334V

Ch2 Max 269mA

(a) (b)

0 100 200 300 400 500

0

5

10

15

20

25

VIPer12A

Amplitude(mA

)

Frequency (kHz)


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Figure 24: Harmonic current spectrum with VIPer22A

8. CONCLUSION

Two solutions have been introduced in order to power a PLMS based on ST7538 chip specifications.

The power supplies have been designed and developed using the VIPower device VIPer12A, since it

represents the device of choice for the considered output power level in terms of performance and price.

The main result of this investigation is that the proposed power supply performs well in terms of line and

load regulation, working in burst mode when the PLMS works in RX mode, thus reducing the maximum

switching frequency to 30kHz.

Using VIPer22A it is possible to reduce the average burst switching frequency to 19KHz, since atransformer with a lower primary inductance than VIPer12A converter can be chosen.

Even if this device is more expensive compared to VIPer12A, the performance in terms of frequency

reduction will be improved and, consequently, the interference with the PLMS will be reduced.

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequencesof use of such information nor for any infringement of patents or other rights of third parties which may results from its use. No license isgranted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication aresubject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics productsare not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

The ST logo is a trademark of STMicroelectronics

2003 STMicroelectronics - Printed in ITALY- All Rights Reserved.

STMicroelectronics GROUP OF COMPANIESAustralia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - I taly - Japan - Malaysia -

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0 100 200 300 400 5000

5

10

15

20

25

VIPer22A

Amplitude(mA)

Frequency (kHz)

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