Features and Benefits
- High Efficiency (Up to 96%) Dual Step-Down Outputs
- 300mA Output Current per Channel at VIN = 3V
- 2.25MHz Constant-Frequency Operation
- 2.5V to 5.5V Input Voltage Range
- Low Dropout Operation: 100% Duty Cycle
- No Schottky Diodes Required
- Internally Compensated for All Ceramic Capacitors
- Independent Internal Soft-Start for Each Channel
- Available in Fixed Output Versions
- 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 Profile (0.75mm) 8-Lead 3mm × 2mm DFN Package
The LTC3547B 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 polymer and USB powered applications. Supply current is only 1µA in shutdown.
An internally set 2.25MHz switching frequency allows the use of tiny surface mount inductors and capacitors. Internal soft-start reduces inrush current during start-up. All outputs are internally compensated to work with ceramic capacitors. The LTC3547B is available in a low proﬁle (0.75mm) 3mm × 2mm DFN package. The LTC3547B is also available in a fixed output voltage configuration selected via internal resistor dividers.
- Cellular Telephones
- Digital Still Cameras
- Wireless and DSL Modems
- Portable Media Players
- PDAs/Palmtop PCs
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.
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:
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.