Features and Benefits
- High Efficiency Triple Step-Down Outputs from a Single Input Supply
- 1A Synchronous Buck Regulator Provides Main Step-Down Output and Powers Two 300mA VLDO™ Linear Regulators
- Output Voltages as Low as 400mV (VLDO Outputs)
- Power Good Output
- Input Voltage Range: 2.7V to 5.5V
- Independent Internal Soft-Start for Each Supply
- Independent Enable Pin for Each Supply
- Low (140µA Typ) No-Load Quiescent Current with All Outputs Enabled
- Constant Frequency Current Mode Operation
- 2.25MHz Switching Frequency Uses Small Inductors
- Defeatable Automatic Burst Mode® Operation for High Efficiency at Light Loads
- ±1.5% Reference Accuracy
- Overtemperature Protection
- Thermally Enhanced 4mm × 3mm 14-Pin DFN Package
The LTC3446 combines a synchronous buck DC/DC converter with two very low dropout (VLDO) linear regulators to provide up to three stepped-down output voltages from a single input voltage. The input voltage range is ideally suited for Li-Ion battery-powered applications, as well as powering low voltage logic from 5V or 3.3V rails. The output voltage range extends down to 0.4V for the VLDO regulators and 0.8V for the buck.
The 1A synchronous buck converter provides the main output with high efficiency, typically 85%. The two 300mA VLDO regulators can run off the main output to provide two additional lower voltage outputs. A built-in supply monitor provides a power good indication.
The buck converter switches at 2.25MHz, allowing the use of small surface mount inductors and capacitors. Constant frequency current mode operation produces controlled output spectrum and fast transient response. A mode-select pin allows automatic Burst Mode operation to be enabled for higher efficiency at light load, or disabled for lower noise operation down to very light loads. The two VLDO regulators are stable with ceramic output capacitors as small as 1µF.
- Low Power Handheld Devices
- Low Voltage and Multivoltage Power for Digital Logic, I/O, FPGAs, CPLDs, ASICs and CPUs
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 893A is a triple output converter using the LTC3446 1A monolithic synchronous buck regulator with dual 300mA very low drop-out linear regulators (VLDOs). The DC893A has an input voltage range of 2.9V to 5.5V, and is capable of delivering up to 400mA of load current on the buck output and up to 300mA on each VLDO output. The buck regulator output voltage of the DC893A can be set as low as 0.8V, and the dual VLDOs can be set as low as 0.4V.
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:
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.