收藏本站
NCP1027
Startup Sequence
The NCP1027 includes a high-voltage startup circuitry,
directly deriving current from the bulk line to charge the
Vbulk
I1
RV CC
V CC capacitor. Figure 24 details the simplified internal
arrangement.
+
1
ICC1
IC1
←
5
I2
I clamp
-
+
+
CV CC
Vz = 8.7 V
V CCon
V CCoff
+
I clamp > 6 mA
→ OVP fault
8
Figure 24. Internal Arrangement of the Startup Circuitry
When the power supply is first connected to the mains
outlet, the internal current source is biased and charges up
the V CC capacitor. When the voltage on this V CC capacitor
reaches the VCC ON level (typically 8.5 V), the current
source turns off, reducing the amount of power being
dissipated. At this time, the V CC capacitor only supplies the
controller, and the auxiliary supply should take over before
V CC collapses below VCC (min) . This V CC capacitor, CV CC ,
must therefore be calculated to hold enough energy so that
V CC stays above VCC (min) (7.3 V typical) until the
auxiliary voltage fully takes over.
An auxiliary winding is needed to maintain the V CC in
order to self-supply the switcher. The V CC capacitor has
only a supply role and its value does not impact other
parameters such as fault duration or the frequency sweep
period for instance. As one can see in Figure 24, an internal
active Zener diode, protects the switcher against lethal V CC
runaways. This situation can occur if the feedback loop
optocoupler fails, for instance, and you would like to
protect the converter against an over voltage event. In that
case, the internal current increase incurred by the V CC
rapid growth triggers the over voltage protection (OVP)
circuit and immediately stops the output pulses for 440 ms.
Then a new startup attempt takes place to check whether
the fault has disappeared or not. The OVP paragraph gives
more design details on this particular section.
The V CC capacitor can be calculated knowing a) the
amount of energy that needs to be stored; b) the time it
takes for the auxiliary voltage to appear, and; c) the current
consumed by the controller at that time. For a better
understanding, Figure 25 shows how the voltage evolves
on the V CC capacitor upon startup.
http://onsemi.com
11
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
NCP1608BOOSTGEVB BOARD EVAL NCP1608 100W BOOST
NCP1631PFCGEVB BOARD DEMO NCP1631 INTERLEAV PFC
NCP1650EVB BOARD EVAL NCP1650 PFC CTLR
NCP1652L48VGEVB BOARD EVAL 100W 48V NCP1652 PFC
NCP1653EVB BOARD EVAL FOR NCP1653
NCP2993FCT2GEVB BOARD EVAL NCP2993 AUDIO PWR AMP
NCP345SNT1G IC DETECTOR OVER VOLTAGE 5TSOP
NCP346SN2T1G IC DETECTOR OVER VOLTAGE 5TSOP
相关代理商/技术参数
NCP1606ADR2G 功能描述:功率因数校正 IC PWR FCTR CONTROLLER RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
NCP1606APG 功能描述:功率因数校正 IC LO CST PWR FCTR CONT RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
NCP1606BDR2G 功能描述:功率因数校正 IC PWR FCTR CONTROLLER RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
NCP1606BOOSTGEVB 功能描述:电源管理IC开发工具 OSPI NCP1606 100 W BOOST 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
NCP1606BPG 功能描述:功率因数校正 IC LO CST PWR FCTR CONT RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
NCP1607BDR2G 功能描述:功率因数校正 IC CST EFCT PW FCTR CTR RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
NCP1607BOOSTGEVB 功能描述:BOARD EVAL NCP1607 100W BOOST RoHS:是 类别:编程器，开发系统 >> 评估演示板和套件 系列:* 标准包装:1 系列:PCI Express® (PCIe) 主要目的:接口，收发器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要属性:- 次要属性:- 已供物品:板
NCP1608BDR2G 功能描述:功率因数校正 IC COST EFFECT PWR FACT CONT RoHS:否 制造商:Fairchild Semiconductor 开关频率:300 KHz 最大功率耗散: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel