ALTAIR04-900TR データシートの表示（PDF） - STMicroelectronics

部品番号

コンポーネント説明

メーカー

ALTAIR04-900TR

Off-line all-primary-sensing switching regulator

STMicroelectronics 

ALTAIR04-900

Application information

Figure 17. Load-dependent operating modes: timing diagrams

COMP

VCOMPL

65 mV

hys ter.

IDS

5.8

Normal-mode

TSTA R T

TS TA RT

TS TA R T

Burst-mode

TST AR T

Normal-mode

Soft-start and starter block

The soft-start feature is automatically implemented by the constant current block, as the

primary peak current is limited on the CREF capacitor.

During the startup, as the output voltage is zero, IC starts in CC-mode without high peak

current operations. The voltage on the output capacitor increases slowly and the soft-start

feature is assured.

Actually the CREF value is not important to define the soft-start time, as its duration depends

on other circuit parameters, such as: transformer ratio, sense resistor, output capacitors and

load. The user can define the best appropriate value.

DocID18211 Rev 3

19/29

29

Share Link: