Features and Benefits
- Low Ripple Burst Mode® Operation
- 2.5µA IQ at 12VIN to 3.3VOUT
- Output Ripple < 5mVP-P
- Wide Input Voltage Range: 4.2V to 40V Operating
- Adjustable Switching Frequency: 200kHz to 2.2MHz
- Integrated Boost and Catch Diodes
- 350mA Output Current
- Fixed Output Voltages:
- 3.3V, 3.42V, 5V
- 1.8μA IQ at 12VIN
- Accurate 1V Enable Pin Threshold
- Low Shutdown Current: IQ = 0.7μA
- Internal Sense Limits Catch Diode Current
- Power Good Flag
- Output Voltage: 1.21V to 25V
- Internal Compensation
- Small 10-Pin MSOP and (3mm × 2mm) DFN Packages
The LT3970 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 40V, and consumes only 2.5μA of quiescent current. A high efficiency switch is included on the die along with the catch diode, boost diode, and the necessary oscillator, control and logic circuitry. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 5mV in a typical application. Current mode topology is used for fast transient response and good loop stability. A catch diode current limit provides protection against shorted outputs and overvoltage conditions. An enable pin with accurate threshold is available, producing a low shutdown current of 0.7μA. A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT3970 is available in small 10-pin MSOP and 3mm × 2mm DFN packages.
- Automotive Battery Regulation
- Power for Portable Products
- Industrial Supplies
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 1566 is a monolithic stepdown DC/DC switching regulator featuring the LT3970. The switching frequency is adjustable up to 2MHz. The demo circuit is designed for 5V, 350mA output from a 6V to 40V input. The wide input range of the LT3970 allows a variety of input sources including automotive batteries and 24V industrial supplies. Low ripple Burst Mode increases the efficiency at the light load while keeping the output ripple below 15mV. The part is in shutdown when the EN pin is low and active when the pin is high. The threshold of the EN pin is accurate at 1V when Vin is above 4.2V. Adding a resistor divider from Vin to EN can program the LT3970 to regulate the
output only when Vin is above a desired voltage. The catch diode and boost diode are integrated to reduce the components count and solution size. The circuit consumes only 2μA of quiescent current. The current mode control scheme creates fast transient response and good loop stability. The catch diode current is limited to protect the part under short circuit and overvoltage conditions.
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
Design tools for the following parts are available in LTpowerCAD:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.