ICE2AS01 datasheet(9/24 Pages) INFINEON

9 / 24 page

Datasheet

30 Jun 2006

Preliminary Data

ICE2AS01/S01G

ICE2BS01/S01G

Functional Description

Figure 8

PWM Controlling

3.3

Soft-Start

Figure 9

Soft-Start Phase

The Soft-Start is realized by the internal pullup resistor

RSoft-Start and the external Capacitor CSoft-Start (see

Figure 2). The Soft-Start voltage VSoftS is generated by

charging the external capacitor CSoft-Start by the internal

pullup resistor RSoft-Start. The Soft-Start-Comparator

compares the voltage at pin SoftS at the negative input

with the ramp signal of the PWM-OP at the positive

input. When Soft-Start voltage VSoftS is less than

Feedback voltage VFB the Soft-Start-Comparator limits

the pulse width by reseting the PWM-Latch (see Figure

9). In addition to Start-Up, Soft-Start is also activated at

each restart attempt during Auto Restart. By means of

the above mentioned CSoft-Start the Soft-Start can be

defined by the user. The Soft-Start is finished when

VSoftS exceeds 5.3V. At that time the Protection Unit is

activated by Comparator C4 and senses the FB by

Comparator C3 wether the voltage is below 4.8V which

means that the voltage on the secondary side of the

SMPS is settled. The internal Zener Diode at SoftS with

breakthrough voltage of 5.6V is to prevent the internal

circuit from saturation (see Figure 10).

Figure 10 Activation of Protection Unit

The Start-Up time TStart-Up within the converter output

voltage VOUT is settled must be shorter than the Soft-

Start Phase TSoft-Start (see Figure 11).

By means of Soft-Start there is an effective

minimization of current and voltage stresses on the

external Power Switch, the clamp circuit and the output

overshoot and prevents saturation of the transformer

during Start-Up.

x3.65

PWM OP

Improved

Current Mode

PWM Comparator

Isense

Soft-Start Comparator

6.5V

PWM-Latch

0.8V

Optocoupler

5.3V

SoftS

Gate Driver

Soft-Start

5.6V

6.5V

Power-Up Reset

5.3V

4.8V

Soft-Start

Error-Latch

PWM-Latch

Clock

Gate

Driver

5.6V

SoftS

−

Start

Soft

Start

Soft

Start

Soft

ICE2AS01 데이터시트(PDF) 9 Page - Infineon Technologies AG

ICE2AS01 데이터시트(HTML) 9 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 23 24

데이터시트 다운로드

링크 URL