Linear LT3991 55V 1.2A降压稳压方案

Linear 公司的LT3991 是静太电流仅为2.8uA的55V 1.2A降压稳压器,输入电压从4.3V到 55V,最大输出电流1.2A,可调整的开关频率从250kHz到2MHz,快速瞬态响应,关断电流仅为700nA,主要用作汽车电池调整,手提设备电源以及工业电源.本文介绍LT3991主要特性, 方框图,以及典型应用电报挂号路,包括5V, 2.5V, 1.8V, 12 V, 3.3V和4V等降压转换器.

LT3991:55V, 1.2A Step-Down Regulator with 2.8μA Quiescent Current

The LT3991 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 55V. Low quiescent current design consumes only 2.8μA of supply current while regulating with no load. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mV in a typical application. An internally compensated current mode topology is used for fast transient response and good loop stability. A high efficiency 0.44Ω switch is included on the die along with a boost Schottky diode and the necessary oscillator, control and logic circuitry.

An accurate 1V threshold enable pin can be used to shut down the LT3991, reducing the input supply current to 700nA. A capacitor on the SS pin provides a controlled inrush current (soft-start). A power good flag signals when VOUT reaches 91% of the programmed output voltage.

The LT3991 is available in small 10-pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance.

LT3991主要特性:

Ultralow Quiescent Current:2.8μA IQ Regulating 12VIN to 3.3VOUT

Low Ripple Burst ModeR Operation:Output Ripple < 15mVP-P

Wide Input Voltage Range: 4.3V to 55V

1.2A Maximum Output Current

Adjustable Switching Frequency: 200kHz to 2MHz

Synchronizable Between 250kHz to 2MHz

Fast Transient Response

Accurate 1V Enable Pin Threshold

Low Shutdown Current: IQ = 700nA

Power Good Flag

Soft-Start Capability

Internal Compensation

Saturating Switch Design: 0.44Ω On-Resistance

Output Voltage: 1.19V to 30V

Small Thermally Enhanced 10-Pin MSOP Package and (3mm x 3mm) DFN Packages

LT3991应用:

Automotive Battery Regulation

Power for Portable Products

Industrial Supplies

图1.LT3991方框图

图2.LT3991 5V降压转换器


图3.LT3991 2.5V降压转换器

图4.LT3991 1.8V降压转换器

图5.LT3991 12 V降压转换器

图6.LT3991 3.3V降压转换器

图7.LT3991 4V降压转换器