系统板 6681

MAXREFDES1187: 7.5W 5V Offline Flyback Converter

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概述

概述

Input Type	V_{IN (MIN)} (V)	V_{IN (MAX)} (V)	I_OUT (A)	Single/Multiple Output	V_OUT (V)	P_OUT (W)	Topology
AC	176	284	1.500	Single	5	7.5	Flyback

The MAX17595 is a peak-current-mode controller for designing wide input-voltage flyback regulators. The MAX17595 offers optimized input thresholds for universal input AC-DC converters and telecom DC-DC (36V to 72V input range) power supplies. It contains a built-in gate driver for an external n-channel MOSFET. The MAX17595 houses an internal error amplifier with 1% accurate reference, eliminating the need for an external reference. The switching frequency is programmable from 100kHz to 1MHz with an accuracy of 8%, allowing optimization of magnetic and filter components, resulting in compact and cost-effective power conversion. For EMI-sensitive applications, the MAX17595 incorporates a programmable frequency dithering scheme, enabling low-EMI spread-spectrum operation. Users can start the power supply precisely at the desired input voltage, implement input overvoltage protection, and program soft-start time. A programmable slope compensation scheme is provided to ensure stability of the peak current-mode control scheme. Hiccup-mode overcurrent protection and thermal shutdown are provided to minimize dissipation in overcurrent and overtemperature fault conditions.

Key Features

Programmable Switching Frequency Allows Optimization of the Magnetic and Filter Components, Resulting in Compact, Cost-Effective, Efficient Isolated/ Nonisolated Power Supplies
100kHz to 1MHz Programmable Switching Frequency with Optional Synchronization
Peak Current Mode Control Provides Excellent Transient Response—Offline (Universal Input AC) and Telecom (36V to 72V) Flyback Controller
Programmable Frequency Dithering Enables Low EMI Spread-Spectrum Operation
Integrated Protection Features Enhance System Reliability
Adjustable Current Limit with External Current Sense Resistor
Fast Cycle-By-Cycle Peak Current Limiting Hiccup-Mode Short-Circuit Protection
Overtemperature Protection
Programmable Soft-Start and Slope Compensation
Input Overvoltage Protection

MAXREFDES1187 Hardware

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Designed, Built, Tested

This document describes the hardware. It provides a detailed systematic technical guide to designing an offline discontinuous conduction mode (DCM) flyback using Maxim’s MAX17595 current-mode controller. The power supply has been built and tested, details of which follow later in this document.