ST AN2063 Application note

October 2004

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2. VIPer12A DESCRIPTION

VIPer12A is a high voltage integrated circuits intended to be used on off line power supply as a primary side switch. in a monolithic structure housed in DIP-8 or SO-8 package it includes a PWM driver, a Power MOSFET with 730V breakdown voltage, a start-up circuit and several protection circuit. It takes advantage from minimizing the external part count, reducing the products size and power consumption. The application note describes the results obtained when VIPer12A is used in mobile charger application.

Short circuit protection

30mVpp

Parameters

Table 1: Operation conditions

In table 1 this charger solution with VIPer12A is presented.

1. INTRODUCTION

The new regulations on the power supply stand-by consumption for theProduct(s)battery charger are becoming more stringent. Thanks to VIPerX2A family low power consumption, it is possible to build a battery

charger with a power consumption in stand-by mode with no-load of 100mW.

Input voltage range 90 to 264VACObsoleteLimits Input frequency range 50-60Hz-

Output voltage Product(s)5V Output current 800mA

Output power 4W

Efficiency 72% typical

Line regulation 0.5% ObsoleteLoad regulation

Output ripple voltage

Safety

VIPower: LOW CONSUMPTION STAND-BY POWER WITH VIPerX2A FAMILY

GENERAL FEATURES

■ ULTRA LOW STANDBY POWER DISSIPATION

■ BURST MODE OPERATION IN STAND-BY

■ 72% TYPICAL EFFICIENCY

■ CURRENT MODE CONTROLLER

■ OUTPUT SHORT CIRCUIT PROTECTION

■ THERMAL SHUT DOWN PROTECTION

AN2063 - APPLICATION NOTE

3. PCB LAY-OUT

The layout of the switching power supply is very important in order to minimize noise and interference. The high switching current loop areas should be kept as small as possible to reduce the radiated electromagnetic emissions. Figure 1 shows the board layout.

In order to meet safety agencies' requirements, there needs to be an adequate clearance of about 6mm between the high and low voltage sides of the circuit.

The power grounds need to be separated from the small signal grounds. The current in the power ground changes very quickly in time; resulting in large transient that induces voltage shifts, which in turn can disturb critical, sensitive small signal currents. Any disturbance or shift of ground in the small signal ground will upset critical reference paths. Therefore, poor grounding routing can manifest itself as poor load regulation, or excessive switching noises on the output.

Figure 1: Demo board bottom foil (not in scale)

Product(s)

4. GENERAL CIRCUIT DESCRIPTION

ObsoleteThis board is a fly-back regulator delivering 0.8A at 5V. The AC input is rectified and filtered by the diode D1, D2, D3, D4, the bulk capacitor C1, and C2 to generate the high voltage DC bus applied to the

primary winding of the transformer, TR1. C1, L1, and C2 provide EMI filtering for the circuit.D9, D10 form the snubber circuit needed to reduce the leakage spike and voltage ringing on the drain pin of VIPer12A. The output voltage is regulated with a TL431 (U3) via an optocoupler (U2) to the feedback pin. The output voltage ripple is controlled with the capacitor, C7, with an additional LC PI filter configuration made up of L2 and C8. It is possible to modify the output voltages by changing the transformer turns ratio and modifying the resistance values of R6 and R7 in the feedback loop.

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NOTE

Product(s)

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- APPLICATION

680µ

D10

AN2063

P6KE180

OptionC

1N5822

4.7µ

1N4007

STTH1L06

470µ

220µ

16V

10V

OptionA

1N4148

Obsolete

D7OptionE

220

4.7µ

1N4148

400V

OptionB

1.5k

43k

PC817

VDD

DRAIN

PC817

C10

1N4007

CONTROL

100n

SOURCE

TL431

OptionE

schematic

33µ

10µ

47n

Product(s)

C11

50V

33V

VIPer12A

43k

1kV

Figure 2: Application

Obsolete

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