LT3971 - 38V, 1.2A, 2MHz Step-Down Regulator with 2.8μA Quiescent Current

Features

• Ultralow Quiescent Current:
  2.8μA I_Q Regulating 12V_IN to 3.3V_OUT
• Low Ripple Burst Mode® Operation:
  Output Ripple < 15mV_P-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: I_Q = 700nA
• Power Good Flag
• Soft-Start Capability
• Internal Compensation
• Saturating Switch Design: 0.33Ω On-Resistance
• Output Voltage: 1.19V to 30V
• Small Thermally Enhanced 10-Pin MSOP Package and (3mm × 3mm) DFN Packages

Typical Application

Description

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 fl ag signals when V_OUT reaches 91% of the programmed output voltage. The LT3971 is available in small 10-pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance.

Packaging

MS-10, DFN-10

Order Info

• Part numbers ending in PBF are lead free. Please contact LTC marketing for information on lead based finish parts.
• Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
• Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number	Package	Pins	Temp	Price (1-99)	Price (1k)*	RoHS Data
LT3971EDD#PBF	DFN	10	E	$3.93	$2.75	View
LT3971EDD#TRPBF	DFN	10	E		$2.81	View
LT3971EMSE#PBF	MSOP	10	E	$3.93	$2.75	View
LT3971EMSE#TRPBF	MSOP	10	E		$2.81	View
LT3971IDD#PBF	DFN	10	I	$4.37	$3.06	View
LT3971IDD#TRPBF	DFN	10	I		$3.12	View
LT3971IMSE#PBF	MSOP	10	I	$4.37	$3.06	View
LT3971IMSE#TRPBF	MSOP	10	I		$3.12	View
Buy Now
Request Samples

^* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

• Automotive Battery Regulation
• Power for Portable Products
• Industrial Supplies

Simulate

LTSpice IV is a powerful FREE circuit simulator and schematic capture program, providing macro models for 80% of Linear Technology's switching regulators, over 200 op amp models, as well as resistors, transistors and MOSFET models.

• Step 1. If you do not already have a copy of LTSpice IV, click here to download and install LTSpice / SwitcherCAD III
  
  
• Step 2. Once LTSpice is installed, click here for a ready to run demonstration circuit of the LT3971.
  
  
• Step 3. If LTspice IV does not automatically open after clicking the above link, you can instead run the simulation by right clicking on the link and selecting “Save Target As”. After saving the file to your computer, start LTSpice and open the demonstration circuit by selecting "Open" from the "File" menu.

For our complete list of hundreds of ready to run demo circuits, visit our LTspice IV Demo Circuits Collection