LTC3447

PRODUCTION

I²C Controllable Buck Regulator in 3mm × 3mm DFN

Part Models: 2
1ku List Price: Starting From $2.42

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Overview

I²C Programmable Output with 21.6mV Resolution
Overtemperature Protected
High Efficiency: Up to 93%
Very Low Quiescent Current: Only 33µA
600mA Output Current at V_IN = 3V
2.5V to 5.5V Input Voltage Range
1MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
Stable with Ceramic Capacitors
Shutdown Mode Draws <1µA Supply Current
±2% Output Voltage Accuracy
Standard (100kHz) or Fast Mode (400kHz) I²C
6-Bit Voltage DAC (0.69V to 2.05V)
Disable Burst Mode Operation
Enable Power Good Blanking
Optional External Start-Up Resistors
Soft-Start
10 Lead, 3mm × 3mm DFN Package

The LTC3447 is a high efficiency monolithic synchronous current mode buck regulator. Using an I²C interface, the output voltage can be set between 0.69V and 2.05V using an internal 6-bit DAC.

The buck regulator has optional external feedback resistors that can be used for setting the initial start up voltage. The feedback voltage reference for this start-up option is 0.6V. Once the voltage DAC is updated via the I²C, the buck regulator switches from external to internal feedback resistors. When there are no external resistors, the default start-up voltage is 1.38V.

The switching frequency is internally set at 1MHz, allowing the use of small surface mount inductors and capacitors.

In Burst Mode^® operation, supply current is only 33µA, dropping to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3447 ideally suited for single cell Li-Ion battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. Automatic Burst Mode operation increases efficiency at light loads, further extending battery life.

The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode.

Protected by U.S. Patents, including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131.

Applications

Distributed Power Supplies
Notebook Computers
PDAs and Other Handheld Devices

Part Models: 2
1ku List Price: Starting From $2.42

Documentation

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. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3447EDD#PBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LTC3447EDD#TRPBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Power System Management (PSM) & Sequencers 1
LTC2974	RECOMMENDED FOR NEW DESIGNS	4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement
Supervisory Circuits & Reset ICs 1
LTC2934	PRODUCTION	Ultra-Low Power Adjustable Supervisor with Power-Fail Output
Switching Regulators & Controllers 1
LTC3880	RECOMMENDED FOR NEW DESIGNS	Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management

Evaluation Kits

LTC3447EDD Demo Board | I2C-Controllable Buck, 2.5V ≤ VIN ≤ 5.5V, VOUT = 0.7V to 2V @ 0.6A

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Product Details

Demonstration Circuit 767 is an I²C-controlled high efficiency synchronous current mode buck regulator featuring the 600mA output LTC3447. The demo board input voltage range is 2.5V to 5.5V. The buck regulator has a programmable output range of 0.7V to 2.00V which is set with an internal 6-bit DAC via the I²C interface. The initial start-up voltage is set to 1.35V but can be change by changing feedback resistors R4 and R5.