Features and Benefits
- High Efficiency Dual Step-Down Outputs: Up to 96%
- 300mA Output Current per Channel at VIN = 3V
- Automatic Low Ripple Burst Mode Operation (20mVP-P).
- Only 40µA Quiescent Current During Operation (Both Channels)
- 2.25MHz Constant-Frequency Operation
- 2.5V to 5.5V Input Voltage Range
- Low Dropout Operation: 100% Duty Cycle
- Internally Compensated for All Ceramic Capacitors
- Independent Internal Soft-Start for Each Channel
- Current Mode Operation for Excellent Line and Load Transient Response
- 0.6V Reference Allows Low Output Voltages
- Short-Circuit Protected
- Ultralow Shutdown Current: IQ < 1µA
- Low Proﬁ le (0.75mm) 8-Lead 3mm × 2mm DFN Package
The LTC3547 is a dual, 2.25MHz, constant-frequency, synchronous step-down DC/DC converter in a tiny 3mm × 2mm DFN package. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Low output voltages are supported with the 0.6V feedback reference voltage. Each regulator can supply 300mA continuous output current.
The input voltage range is 2.5V to 5.5V, making it ideal for Li-Ion and USB powered applications. Supply current during operation is only 40µA and drops to < 1µA in shutdown. Automatic Burst Mode® operation increases efficiency at light loads, further extending battery life.
An internally set 2.25MHz switching frequency allows the use of tiny surface mount inductors and capacitors. Internal soft-start reduces inrush current during startup. All outputs are internally compensated to work with ceramic capacitors. The LTC3547 is available in a low profile (0.75mm) 3mm × 2mm DFN package.The LTC3547is also available in a fixed output voltage configuration,eliminating the need for the external feedback networks
- Cellular Telephones
- Digital Still Cameras
- Wireless and DSL Modems
- PDAs/Palmtop PCs
- Portable Media Players
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 1013 is a dual output regulator consisting of two constant-frequency step-down converters, based on the LTC3547 monolithic dual synchronous buck regulator IC. The DC1013 has an input voltage range of 2.5V to 5.5V, and both outputs are capable of delivering up to 300 mA of output current at a minimum input voltage of 3V. In Burst Mode® operation, which is the mode of the LTC3547 during light load current operation, the DC supply current of the DC1013 is typically only 40 uA (per channel) at no load, and less than 1 uA in shutdown. The DC1013 is a very efficient circuit: over 95% for either circuit. The LTC3547 comes in a tiny 8-lead 3 × 2 mm DFN package, which has an exposed pad on the bottom-side of the IC for better thermal performance.
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:
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Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.