Linear LT3980 2.4MHz 2A降压稳压方案

Linear 公司的LT3980是58V 2.4MHz 2A降压开关稳压器,静态电流仅为85uA.可关频率可从100kHz到2.4MHz调整,输入电压高达58V(瞬态电压80V),输出电流高达2A,主要应用在汽车电子,分布式电源,工业电源和墙变压器调整等.本文介绍了LT3980的主要特性,方框图以及典型应用电路,包括5V,3.3V,2.5V,12V和1.8V降压转换器电路图.

58V, 2A, 2.4MHz Step-Down Switching Regulator with 85μA Quiescent Current The LT3980 is an adjustable frequency (100kHz to 2.4MHz) monolithic buck switching regulator that accepts input voltages up to 58V (80V transient). A high efficiency 200mΩ switch is included on the die along with a boost Schottky diode and the necessary oscillator, control, and logic circuitry. Current mode topology is used for fast transient response and good loop stability. Catch diode current sense (DA pin) protects the circuit during input voltage transients even when a high switching frequency is used. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mV in a typical application. In addition, the LT3980 can further enhance low output current efficiency by drawing bias current from the output when VOUT is above 3V. Shutdown reduces input supply current to less than 1μA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start).

A power good flag signals when VOUT reaches 91% of the programmed output voltage. The LT3980 is available in 16-pin MSOP and 3mmx4mm DFN packages with exposed pads for low thermal resistance.

LT3980主要特性:

■ Wide Input Range: Operation from 3.6V to 58V

■ Overvoltage Lockout Protects Circuits Through 80V Transients

■ 2A Maximum Output Current

■ Low Ripple (<15mVP-P) Burst Mode Operation:

IQ= 85μA at 12VIN to 3.3VOUT

■ Adjustable Switching Frequency: 100kHz to 2.4MHz

■ Low Shutdown Current: IQ < 1μA

■ Catch Diode Current Sense Protects Circuit Through Short-Circuit and Input Overvoltage

■ Synchronizable Between 250kHz to 2MHz

■ Power Good Flag

■ Saturating Switch Design: 200mΩ On-Resistance

■ Thermal Protection

■ Soft-Start Capability

■ Small 16-Pin Thermally Enhanced MSOP and 3mmx 4mm DFN Packages

LT3980应用:

■ Automotive Battery Regulation

■ Distributed Supply Regulation

■ Industrial Supplies

■ Wall Transformer Regulation

图1.LT3980方框图

图2.LT3980 5V降压转换器电路图

图3.LT3980 3.3V降压转换器电路图


图4.LT3980 2.5V降压转换器电路图


图5.LT3980 5V 1.2MHz降压转换器电路图


图6.LT3980 12V降压转换器电路图


图7.LT3980 1.8V降压转换器电路图