Features and Benefits
- I2C Programmable Output with 21.6mV Resolution
- Overtemperature Protected
- High Efficiency: Up to 93%
- Very Low Quiescent Current: Only 33µA
- 600mA Output Current at VIN = 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
- 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.
- Distributed Power Supplies
- Notebook Computers
- PDAs and Other Handheld Devices
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 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.
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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.