NS LM5088 75V输入异步降压电源控制方案

NS 公司的LM5088是75V高电压输入异步稳压控制器,能驱动高边N-MOSFET,具有能以最少外接元件来实现高效高输入电压降压转换器所需要的全部功能.LM50888的输入电压可从4.5V到75V,开关频率从50kHz到1MHz可编程.本文介绍了LM5088的主要特性,方框图和应用电路,以及两种评估板电路图与所用材料清单.

LM5088: Wide Input Range Non-Synchronous Buck Controller
The LM5088 high voltage non-synchronous buck controller features all the necessary functions to implement an efficient high voltage buck converter using a minimum number of external components. The LM5088 can be configured to operate over an ultra-wide input voltage range of 4.5V to 75V. This easy to use controller includes a level shifted gate driver capable of controlling an external N-channel buck switch. The control method is based upon peak current mode control utilizing an emulated current ramp. The use of an emulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable control of very small duty cycles necessary in high input voltage/low output voltage applications.
The LM5088 switching frequency is programmable from 50 kHz to 1 MHz. The LM5088 is available in two versions: The LM5088-1 provides a +/-5% frequency dithering function to reduce the conducted and radiated EMI, while the LM5088-2 provides a versatile restart timer for overload protection. Additional features include a low dropout bias regulator, tri-level enable input to control shutdown and standby modes, soft-start and oscillator synchronization capability. The device is available in a thermally enhanced TSSOP-16EP pin package.
LM5088主要特性:
■ Emulated current mode control
■ Drives external high-side N-channel MOSFET
■ Ultra-wide input voltage range from 4.5V to 75V
■ Low IQ Shutdown and Standby modes
■ High duty cycle ratio feature for reduced dropout voltage
■ Spread spectrum EMI reduction (LM5088-1)
■ Hiccup timer for overload protection (LM5088-2)
■ Adjustable output voltage from 1.205V with 1.5% feedback reference accuracy
■ Wide bandwidth error amplifier
■ Single resistor oscillator frequency setting
■ Oscillator synchronization capability
■ Programmable soft-start
■ High voltage, low dropout bias regulator
■ Thermal shutdown protection
Package
■ TSSOP-16EP



图1.简化的LM5088应用电路



图2.LM5088方框图



图3.LM5088-1评估板电路图(1)



图4.LM5088-2评估板电路图(2)



LM5088评估板材料清单(BOM):