Features and Benefits
- Wide Input Voltage Range: 3.7V to 36V
- Two 1.4A Output Switching Regulators with Internal Power Switches
- Adjustable 250kHz to 2.5MHz Switching Frequency
- Synchronizable over the Full Frequency Range
- Anti-Phase Switching Reduces Ripple
- Uses Small Inductors and Ceramic Capacitors
- Accurate Programmable Undervoltage Lockout
- Independent Tracking, Soft-Start and Power Good Circuits Ease Supply Sequencing
- Output Adjustable Down to 800mV
- Small 4mm × 4mm 24-Pin QFN or 16-Pin Thermally Enhanced TSSOP Surface Mount Packages
The LT3508 is a dual current mode PWM step-down DC/DC converter with internal power switches capable of generating two 1.4A outputs. The wide input voltage range of 3.7V to 36V makes the LT3508 suitable for regulating power from a wide variety of sources, including automotive batteries, 24V industrial supplies and unregulated wall adapters. Both converters are synchronized to a single oscillator programmable up to 2.5MHz and run with opposite phases, reducing input ripple current. Its high operating frequency allows the use of small, low cost inductors and ceramic capacitors, resulting in low, predictable output ripple. Each regulator has independent tracking and soft-start circuits and generates a power good signal when its output is in regulation, easing power supply sequencing and interfacing with microcontrollers and DSPs.
Cycle-by-cycle current limit, frequency foldback and thermal shutdown provide protection against shorted outputs, and soft-start eliminates input current surge during startup. The low current (<2µA) shutdown mode enables easy power management in battery-powered systems.
- DSP Power Supplies
- Wall Transformer Regulation
- DSL and Cable Modems
- PCI Express
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 1060 features two LT3508 step-down DC/DC switching converters. One circuit uses the LT3508EFE and the other circuit has the LT3508EUF. The LT3508 dual output step-down switching regulator has two internal power switches, a wide input voltage range, adjustable switching frequency synchronizable over the frequency range, programmable soft-start, tracking, power-good, and channel sequencing. The anti-phase switching reduces the input capacitor. The wide VIN range of the LT3508 allows step-down configurations with up to 36V input. The high power internal switches have current limit that allows for up to 1.4A output on each output.
The demonstration circuit has two circuits. The top is optimized for high efficiency, wide input range and maximum output current; the bottom is optimized for the size. The top circuit is rated for 3.3V at 1.4A and 5V at 1.4A output from a 6V–36V input using the FE package. The frequency is set to 700kHz to allow for the high VIN to VOUT ratio and provides high efficiency throughout the range. The bottom circuit generates 1.8V at 1A and 3.3V at 1A from a 5V to 16V DC input using the QFN package and shows off the compact size with 1.6MHz switching frequency.
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)
Press Releases (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.