15V, 2.5A Synchronous Step-Up DC/DC Converter with Output Disconnect
Features and Benefits
- VIN Range: 1.8V to 5.5V, 500mV After Start-Up
- Output Voltage Range: 2.2V to 15V
- 400mA Output Current for VIN = 5V and VOUT = 12V
- Output Disconnects from Input When Shut Down
- Synchronous Rectification: Up to 95% Efficiency
- Inrush Current Limit
- Up to 3MHz Adjustable Switching Frequency Synchronizable to External Clock
- Selectable Burst Mode® Operation: 25μA IQ
- Output Overvoltage Protection
- <1μA IQ in Shutdown
- 12-Lead, 3mm × 4mm Thermally Enhanced DFN Package
The LTC3121 is a synchronous step-up DC/DC converter with true output disconnect and inrush current limiting. The 1.5A current limit along with the ability to program output voltages up to 15V makes the LTC3121 well suited for a variety of demanding applications. Once started, operation will continue with inputs down to 500mV, extending run time in many applications.
The LTC3121 features output disconnect in shutdown, dramatically reducing input power drain and enabling VOUT to completely discharge. Adjustable PWM switching from 100kHz to 3MHz optimizes applications for highest efficiency or smallest solution footprint. The oscillator can also be synchronized to an external clock for noise sensitive applications. Selectable Burst Mode operation reduces quiescent current to 25μA, ensuring high efficiency across the entire load range. An internal soft-start limits inrush current during start-up.
Other features include a <1μA shutdown current and robust protection under short-circuit, thermal overload, and output overvoltage conditions. The LTC3121 is offered in a low profile 12-lead (3mm × 4mm × 0.75mm) DFN package.
- PCI Express Cards/Systems
- Piezo Actuators
- Small DC Motors
- 12V Analog Rail From Battery, 5V, or Backup Capacitor
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 2372A is a 5.5V input, 12V output at 400mA DC/DC power supply featuring the LTC3121. The IC includes internal high and low side 1.5A switches and features selectable PWM or Burst Mode® operation for high efficiency at low output current. The board operates from an input voltage as low as 1.8V and continues to operate down to 500mV once started. The output is fixed at 12V although other voltages between 2.2V and 15V can be selected by resistor changes.
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.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
Design tools for the following parts are available in LTpowerCAD:
LTC3121 Companion Parts
Recommended Related Parts
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.