NCP1217A中文资料PWM Controller, Fixed Frequency, Current Mode, with Duty Cycle Limited to 50%数据手册ONSEMI规格书

描述 Description

Housed in a SOIC-7 or PDIP-7 package, the NCP1217 represents the second generation of NCP1203-based controllers. Thanks to its high drive capability, NCP1217 drives large gate-charge MOSFETs, which together with internal ramp compensation and built-in over voltage protection, ease the design of modern AC/DC adapters. NCP1217 offers a true alternative to UC384X-based designs.With an internal structure operating at different fixed frequencies (65, 100, 133kHz), the controller features a high-voltage start-up FET, which ensures a clean and loss less startup sequence. Its current-mode control topology provides an excellent input audio-susceptibility and inherent pulse-by-pulse control. Internal ramp compensation easily prevents subharmonic oscillations from taking place in continuous conduction mode designs.When the current setpoint falls below a given value, e.g. the output power demand diminishes, the IC automatically enters the so-called skip cycle mode and provides excellent efficiency at light loads. Because this occurs at a user adjustable low peak current, no acoustic noise takes place.The NCP1217 features two efficient protective circuitries: 1) in presence of an over-current condition, the output pulses are disabled and the device enters a safe burst mode, trying to re-start. Once the default has gone, the device auto-recovers. 2) if an external signal (e.g. a temperature sensor) pulls pin1 above 3.2V, output pulses are immediately stopped and the NCP1217 stays latched in this position. Reset occurs when the VCC collapses to ground, e.g. the user un-plugs the power supply.

特性 Features

Current-Mode with adjustable skip-cycle capability
Built-in internal ramp compensation
Auto-recovery internal output short-circuit protection
Full latch-off if Adjustment pin is brought high
Extremely low no-load standby power
Internal temperature shutdown
500mA peak current capability
Fixed frequency versions at 65kHz, 100kHz and 133kHz
Direct optocoupler connection
Internal Leading Edge Blanking
SPICE models available for TRANsient and AC analysis
Internal 1ms Soft start (A version only)
Limited Duty Cycle to 50% (A version only)
Pb-Free Packages are Available

应用 Application

High power AC/DC converters for TVs, set-top boxes etcOffline adapters for notebooksTelecom DC-DC convertersAll power supplies

简介

NCP1217A属于集成电路（IC）的ACDC转换器离线开关。由制造生产的NCP1217AAC DC 转换器，离线开关该系列是元器件级控制产品，用于构建将交流市电转换为直流电（通常电压大幅降低）的设备。集成和未集成系统主要开关元件的器件均包括在内。由于高输入输出电压比，以及此类系统中通常需要隔离，这些器件通常与外部变压器配合使用。尽管通常使用定制变压器来实现此用途，但也有许多专门用于此用途的库存产品，请参见“开关转换器，SMPS 变压器”标题。