ICE3AS02G datasheet(8/22 Pages) INFINEON

8 / 22 page

Version 1.2

02 Sep 2005

ICE3AS02 / ICE3AS02G / ICE3BS02 / ICE3BS02G

Functional Description

All values which are used in the functional description are

typical values. For calculating the worst cases the min/max

values which can be found in section 4 Electrical

Characteristics have to be considered.

3.1

Introduction

The F3 is the further development of the F2 to meet the

requirements for the lowest Standby Power at minimum load

and no load conditions. A new fully integrated Standby

Power concept is implemented into the IC in order to keep

the application design easy. Compared to F2 no further

external parts are needed to achieve the lowest Standby

Power. An intelligent Active Burst Mode is used for this

Standby Mode. After entering this mode there is still a full

control of the power conversion by the secondary side via the

same optocoupler that is used for the normal PWM control.

The response on load jumps is optimized. The voltage ripple

on Vout is minimized. Vout is further on well controlled in this

mode.

The usually external connected RC-filter in the feedback line

after the optocoupler is integrated in the IC to reduce the

external part count.

Furthermore a high voltage startup cell is integrated into the

IC which is switched off once the Undervoltage Lockout on-

threshold of 15V is exceeded. The external startup resistor is

no longer necessary. Power losses are therefore reduced.

This increases the efficiency under light load conditions

drastically.

The Soft-Start capacitor is also used for providing an

adjustable blanking window for high load jumps. During this

time window the overload detection is disabled. With this

concept no further external components are necessary to

adjust the blanking window.

An Auto Restart Mode is implemented in the IC to reduce the

average power conversion in the event of malfunction or

unsafe operating condition in the SMPS system. This feature

increases the system’s robustness and safety which would

otherwise lead to a destruction of the SMPS. Once the

malfunction is removed, normal operation is automatically

initiated after the next Start Up Phase.

The internal precise peak current limitation reduces the costs

for the transformer and the secondary diode. The influence

of the change in the input voltage on the power limitation can

be avoided together with the integrated Propagation Delay

Compensation. Therefore the maximum power is nearly

independent on the input voltage which is required for wide

range SMPS. There is no need for an extra over-sizing of the

SMPS, e.g. the transformer or PowerMOS.

3.2

Power Management

Figure 4

Power Management

The Undervoltage Lockout monitors the external supply

voltage VVCC. When the SMPS is plugged to the main line

the internal Startup Cell is biased and starts to charge the

external capacitor CVCC which is connected to the VCC pin.

This VCC charge current which is provided by the Startup

Cell from the HV pin is 1.05mA. When VVCC exceeds the on-

threshold VCCon=15V the internal voltage reference and bias

circuit are switched on. Then the Startup Cell is switched off

by the Undervoltage Lockout and therefore no power losses

present due to the connection of the Startup Cell to the bus

voltage (HV). To avoid uncontrolled ringing at switch-on a

hysteresis is implemented. The switch-off of the controller

can only take place after Active Mode was entered and VVCC

falls below 8.5V.

The maximum current consumption before the controller is

activated is about 160

µA.

When VVCC falls below the off-threshold VCCoff=8.5V the

internal reference is switched off and the Power Down reset

let T1 discharging the soft-start capacitor CSoftS at pin SoftS.

Thus it is ensured that at every startup cycle the voltage ramp

at pin SoftS starts at zero.

The internal Voltage Reference is switched off if Auto

Restart Mode is entered. The current consumption is then

reduced to 300

µA.

Once the malfunction condition is removed, this block will

then turn back on. The recovery from Auto Restart Mode

does not require disconnecting the SMPS from the AC line.

Power Management

6.5V

SoftS

Active Burst Mode

Auto Restart Mode

Internal Bias

Voltage

Reference

Startup Cell

VCC

Undervoltage Lockout

15V

8.5V

ICE3AS02G датащи(PDF) 8 Page - Infineon Technologies AG

ICE3AS02G датащи(HTML) 8 Page - Infineon Technologies AG

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

датащи скачать

ссылки URL