收藏本站
RDR-91 12 V, 1 A, Universal Input Supply
11-Feb-13
4.3 Output Rectification and Filtering
Diode D7 rectifies the output of T1. Output voltage ripple was minimized by using a low
ESR capacitor for C10 (see Section 6 for component part numbers and values). A post
filter (ferrite bead L2 and C11) attenuates the high frequency switching noise.
4.4 Feedback and Output Voltage Regulation
The supply’s output voltage regulation set point is set by the voltage that develops across
Zener diode VR3, R6 and the LED in optocoupler U2. The value of R4 was calculated to
bias VR3 to about 0.5 mA when it goes into reverse avalanche conduction. This ensures
that it is operating close to its rated knee current. Resistor R6 limits the maximum current
during load transients. The values of R4 and R6 can both be varied slightly to fine-tune
the output regulation set point. When the output voltage rises above the set point, the
LED in U2 becomes forward biased. On the primary-side, the photo-transistor of U2 turns
on and draws current out of the EN/UV pin of U1. Just before the start of each switching
cycle, the controller checks the EN/UV pin current. If the current flowing out of the EN/UV
pin is greater than 115 ? A, that switching cycle will be disabled. As switching cycles are
enabled and disabled, the output voltage is kept very close to the regulation set point.
For greater output voltage regulation accuracy, a reference IC such as a TL431 can be
used in place of VR3.
4.5 Output Overvoltage Shutdown
The TinySwitch-III family of ICs can detect overvoltage on the output of the supply and
latch off. This protects the load in an open feedback loop fault condition, such as the
failure of the optocoupler. Overvoltage on the output is detected through the
BYPASS/MULTI-FUNCTION (BP/M) pin and the bias winding on the transformer. The
bias winding voltage is determined by the reflection of the output voltage through the
turns ratio of the transformer. Therefore, an overvoltage on the output will be reflected
onto the bias winding. The overvoltage threshold is the sum of the breakdown voltage of
Zener diode VR2 and the BP/M pin voltage (28 V + 5.8 V). If the output voltage becomes
abnormally high, the voltage on the bias winding will exceed the threshold voltage and
excess current will flow into the BP/M pin. The latching shutdown circuit is activated when
current into the BP/M pin exceeds 5 mA. Resetting a latched shutdown requires removing
the AC input from the supply long enough to allow the input capacitors (C1 and C2) to
discharge, and the BP/M pin voltage to drop below 2 V. Resistors R7 and R3 provide
additional filtering of the bias voltage, with R3 also limiting the maximum current into the
BYPASS pin in an OV condition
4.6 EMI Design Aspects
An input pi filter (C1, L1 and C2) attenuates conducted, differential mode EMI noise.
Shielding techniques (E-Shield?) were used in the construction of T1 to reduce common
mode EMI displacement currents. Resistor R2 and capacitor C4 dampen out some of the
high frequency ringing that occurs when the power MOSFET turns off. When combined
with the IC’s frequency jitter function, these techniques produce excellent conducted and
radiated EMI performance (see Section 12 of this report).
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 8 of 35
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
DAL3W3P300G30LF CONN DSUB PLUG 3W3 T/H GOLD
DAL3W3S300G30LF CONN DSUB RCPT 3W3 T/H GOLD
DAL7W2P300G30LF CONN DSUB PLUG 7W2 T/H GOLD
DAL7W2P300G40LF CONN DSUB PLUG 7W2 T/H GOLD
DAL7W2P500G30LF CONN DSUB PLUG 7W2 T/H RA GOLD
DAL7W2S500G30LF CONN DSUB RCPT 7W2 T/H R/A GOLD
DAL7W2SA00LF DSUB POWER STB 7W2 SOCK
DAM15P300 CONN DSUB PLUG 15POS STR SOLDER
相关代理商/技术参数
DAK-93 功能描述:电源管理IC开发工具 ACDC peak mode power Supply PeakSwitch RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V
DAK95-16S 制造商:Amphenol Corporation 功能描述:DAK95-16S - Bulk
DAK95-20 制造商:Daniels Manufacturing Corporation (DMC) 功能描述:TOOL INS TWEEZER MS27495A20 , ROHS COMPLIANT: YES
DAK95-20B 制造商:Daniels Manufacturing Corporation (DMC) 功能描述:INSTALLING TWEEZER M81969/8-05
DAK95-20S 制造商:Amphenol Corporation 功能描述:DAK95-20S - Bulk
DAK95-22 制造商:Daniels Manufacturing Corporation (DMC) 功能描述:TOOL INS TWEEZER MS27495A22
DAK95-22M 制造商:Daniels Manufacturing Corporation (DMC) 功能描述:TOOL INS TWEEZER MS27495A22M
DAK95-22MB 制造商:Amphenol Corporation 功能描述:DAK95-22MB - Bulk 制造商:Daniels Manufacturing Corporation (DMC) 功能描述:INSTALLING TWEEZERS, Tool Body Material:- , RoHS Compliant: Yes