LT3971

PRODUCTION

38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA Quiescent Current

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Overview

  • Ultralow Quiescent Current: 2.8μA IQ Regulating 12VIN to 3.3VOUT
  • Fixed Output Voltages: 3.3V, 5V, 2.1μA IQ Regulating 12VIN to 3.3VOUT
  • Low Ripple Burst Mode® Operation: Output Ripple < 15mVP-P
  • Wide Input Voltage Range: 4.3V to 38V
  • 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
  • Output Voltage: 1.19V to 30V
  • Small Thermally Enhanced 10-Lead MSOP, 16-Lead MSOP and (3mm × 3mm) DFN Packages

The LT3971 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 38V. 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 0.33Ω 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 LT3971, 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 LT3971 is available in small 10-lead MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance. A 16-lead MSOP is also offered which has enhanced pin-to-pin fault tolerance.

Vout Iout Vref Accuracy
LT3971 Adj 1.2A 2.5%
LT3971-3.3 3.3V 1.2A 2.5%
LT3971-5 5V 1.2A 2.5%
LT3971A Adj 1.3A 1.5%
LT3971A-5 5V 1.3A 1.5%

Applications

  • Automotive Battery Regulation
  • Power for Portable Products
  • Industrial Supplies
LT3971
38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA Quiescent Current
3.3V Step Down Converter No Load Supply Current Product Package 1 Product Package 2 Product Package 3 Product Package 4 Product Package 5
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Technical Articles 1

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Circuit Monitors 1
LTC2960
RECOMMENDED FOR NEW DESIGNS 36V Nano-Current Two-Input Voltage Monitor
Oscillators 1
LTC6930-X.XX
32.768kHz to 8.192MHz Precision µPower Oscillators
Protection Switches & Controllers 2
LTC4359
RECOMMENDED FOR NEW DESIGNS Ideal Diode Controller with Reverse Input Protection
LTC4365
RECOMMENDED FOR NEW DESIGNS Overvoltage, Undervoltage and Reverse Supply Protection Controller
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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LT3971
  • LT3971-3.3
  • LT3971-5
  • LT3971A
  • LT3971A-5
LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Evaluation Kits

eval board
schematic 1
DC1527A

LT3971EMSE Demo Board | 4.5V ≤ VIN ≤ 38V, VOUT = 3.3V @ 1.2A

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Product Details

Demonstration circuit 1527 is a monolithic step-down DC/DC switching regulator featuring the LT3971. The switching frequency is adjustable up to 2MHz. The demo circuit is designed for 3.3V, 1.2A output from a 4.5V to 38V input. The circuit consumes only 2.8μA of quiescent current.
DC1527A
LT3971EMSE Demo Board | 4.5V ≤ VIN ≤ 38V, VOUT = 3.3V @ 1.2A
DC1527A - Schematic

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