Features and Benefits
- High Efficiency: Up to 96%
- Very Low Quiescent Supply Current: 32µA During Linear Regulator Operation
- 600mA Output Current (Buck Converter)
- Optionally Operates as Linear Regulator Below 3mA—External or Automatic ON/OFF
- 2.5V to 5.5V Input Voltage Range
- 1.5MHz or 2.25MHz Constant Frequency Operation or External Synchronization
- No Schottky Diode Required
- Low Dropout Operation: 100% Duty Cycle
- 0.6V Reference Allows Low Output Voltages
- Shutdown Mode Draws < 1µA Supply Current
- Current Mode Operation for Excellent Line and Load Transient Response
- Overtemperature Protected
- Low Profile (3mm × 3mm) 8-Lead DFN and 8-Lead MSOP Packages
The LTC3448 is a high efficiency, monolithic, synchronous buck regulator using a constant frequency, current mode architecture. Supply current during operation is only 32µA (linear regulator mode) and drops to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3448 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. At moderate output load levels, PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications.
The LTC3448 automatically switches into linear regulator operation at very low load currents to maintain <5mVP-P output voltage ripple. Supply current in this mode is typically 32µA. The switch to linear regulator mode occurs at a threshold of 3mA. Linear regulator operation can be set to on, off or automatic turn on/off.
Switching frequency is selectable at either 1.5MHz or 2.25MHz, allowing the use of small surface mount inductors and capacitors.
The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The LTC3448 is available in a low profile 3mm × 3mm DFN package or thermally enhanced 8-lead MSOP.
Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131. Others pending.
- Cellular Telephones
- Personal Information Appliances
- Wireless and DSL Modems
- Digital Still Cameras
- MP3 Players
- Portable Instruments
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 DC840 is a step-down converter using the LTC3448 monolithic synchronous buck regulator. The DC840 has an input voltage range of 2.5V to 5.5V, and is capable of delivering up to 600mA of output current. The output voltage of DC840 can be set as low as 0.6V, the reference voltage of the LTC3448. The DC840 is especially made for noise sensitive applications, due to a unique design that allows the LTC3448 to automatically switch in auto mode - from a switching regulator to a linear regulator at low output currents.
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:
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.