电源设计实例

本资料包含pdf文件1个，下载需要5积分

电源设计实例Design Highlights
Replaces a linear transformer based supply at the same or
lower cost but with much higher performance
<0.3 W consumption at zero load meets worldwide guidelines
(ECs 0.3 W， USAs 1 W for example)
Extremely simple circuit – only 15 components for production-
worthy design
Primary based CV/CC output – no secondary sense compo-
nents required
±10% output voltage and ±22% output current tolerances at
peak power point
Fully protected for thermal， short circuit and open loop faults
>62% effi ciency (>70% with R1 replaced by an inductor)
Meets CISPR22B/EN55022B EMI limits with low cost resistive
•
•
•
•
•
•
•
•
the transformer (formed from part of the primary) the design meets
conducted EMI limits with no Y-capacitor between primary and
secondary. Resistor RF1 also functions as a fuse.
LinkSwitch derives all feedback information from the primary.
During output diode conduction， the output voltage transformed
through the turns ratio is sampled and held by C4. The feedback
voltage across C4 (VOR) is converted into feedback current by R2
and fed into the CONTROL pin. This feedback current regulates
the output by PWM control during CV operation， and by reducing
the internal current limit during CC operation. Below an output
voltage of 2 V， LinkSwitch enters auto-restart， limiting average
output current to <50 mA. The nominal transition from CV to CC
occurs at 5.5 V， 0.27 A. The output envelope characteristic and