Features and Benefits
- Two 700mA Switching Regulators with Internal Power Switches
- Wide 3.6V to 36V Operating Range
- Overvoltage Lockout Protects Circuit Through 60V Supply Transients
- Short-Circuit Robust
- Low Dropout Voltage: 95% Maximum Duty Cycle
- Adjustable 300kHz to 2.2MHz Switching Frequency Synchronizable Over the Full Range
- Uses Small Inductors and Ceramic Capacitors
- Integrated Boost Diodes
- Internal Compensation
- Thermally Enhanced 14-Lead (4mm × 3mm) DFN and 16 Lead MSOP Packages
The LT3509 is a dual, current mode, step-down switching regulator, with internal power switches each capable of providing 700mA output current. This regulator provides a compact and robust solution for multi-rail systems in harsh environments. It incorporates several protection features including overvoltage lockout and cycle-by-cycle current limit. Thermal shutdown provides additional protection. The loop compensation components and the boost diodes are integrated on-chip. Switching frequency is set by a single external resistor. External synchronization is also possible. The high maximum switching frequency allows the use of small inductors and ceramic capacitors for low ripple. Constant frequency operation above the AM band avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator has an independent shutdown and soft-start control pin. When both converters are powered down, the common circuitry enters a low current shutdown state.
- Automotive Electronics
- Industrial Controls
- Wall Transformer Regulation
- Networking Devices
- CPU, DSP, or FPGA Power
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 1248 is a dual monolithic buck regulator featuring the LT3509. The demo circuit is designed for 5V@700mA and 3.3V@700mA output from a 6.5V to 36V input. The input voltage can go up to 60V without damaging the part. The switching frequency can be set from 300kHz to 2.2MHz by a single external resistor, and it is synchronizable over the full range. The power switches, the compensation components and the boost diodes are all integrated into the silicon. The shutdown and soft start function is independent for each channel. The current mode control scheme creates fast transient response and good loop stability. The part has overvoltage lockout, cycle by cycle current limit and thermal shutdown. DA pin can further protect the silicon under fault conditions by sensing the diode current.
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:
Solutions Bulletins & Brochures (1)
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.