Linear LT4356-3高壓瞬變負載保護方案

使輸出限制在安全數值. LT4356-3還能監視VCC和藹SNS引腳的電壓降,從而保護過流所引器的問題. LT4356-3工作電壓從4V到80V,反向輸入保護到-60V,關斷引腳能經受-60V到100V電壓,關斷電流僅為7uA,可用在汽車和軍用飛機的浪涌保護,熱插拔,以及固有安全應用.本文介紹了LT4356-3的主要特性,方框圖,多種保護應用電路以及DC1018評估板的電路圖。

The LT4356-3 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET.

The output is limited to a safe value thereby allowing the loads to continue functioning. The LT4356-3 also monitors the voltage drop between the VCC and SNS pins to protect against overcurrent faults. An internal amplifier limits the current sense voltage to 50mV. In either fault condition, a timer is started inversely proportional to MOSFET stress. If the timer expires, the FLT pin pulls low to warn of an impending power down. If the condition persists, the MOSFET is turned off, until the SHDN pin pulls low momentarily.

The spare amplifier may be used as a voltage detection comparator or as a linear regulator controller driving an external PNP pass transistor. Back-to-back FETs can be used in lieu of a Schottky diode for reverse input protection, reducing voltage drop and power loss. A shutdown pin reduces the quiescent current to less than 7μA during shutdown.

LT4356-3主要特性:

Stops High Voltage Surges

Adjustable Output Clamp Voltage

Overcurrent Protection

Wide Operation Range: 4V to 80V

Reverse Input Protection to –60V

Low 7μA Shutdown Current

Adjustable Latchoff Fault Timer

Controls N-channel MOSFET

Shutdown Pin Withstands –60V to 100V

Fault Output Indication

Spare Amplifi er for Level Detection Comparator or

Linear Regulator Controller

Available in (4mm 3mm) 12-Pin DFN, 10-Pin MSOP or 16-Pin SO Packages

LT4356-3應用:

Automotive/Avionic Surge Protection

Hot Swap/Live Insertion

High Side Switch for Battery Powered Systems

Intrinsic Safety Applications

圖1. LT4356-3方框圖

圖2.帶N-MOSFET反相輸入保護的過壓穩壓器電路圖

圖3.帶P-MOSFET反相輸入保護的過壓穩壓器電路圖

圖4.帶低電池檢測的穩壓器電路圖

圖5.Vin能經受150V的24V過壓穩壓器電路圖

圖6.帶低電池檢測,關斷時輸出依然工作的過壓穩壓器電路圖

圖7.帶過壓輸出穩壓器(72V)的2.5A 48V熱插拔電路圖

圖8.帶過壓輸出穩壓器(36V)的2.5A 48V熱插拔電路圖

圖9.反向輸入保護高達-80V的過壓穩壓器

DC1018 - LT4356-1 評估套件

Demonstration Circuit DC-1018A showcases the LT4356 Surge Stopper in a 12V, 3A application. Input transients of up to 60V are limited to 16V at the output; sustained overvoltage conditions cause the limiter to trip off and retry after the overvoltage is removed.

圖10.DC1018評估板電路圖