Features and Benefits
- 3.6V to 20V Input Voltage Range
- 3A Output Current per Channel
- Up to 95% Efficiency
- Low Duty Cycle Operation: 5% at 2.25MHz
- Selectable 0°/180° Phase Shift Between Channels
- Adjustable Switching Frequency: 500kHz to 4MHz
- External Frequency Synchronization
- Current Mode Operation for Excellent Line and Load Transient Response
- 0.6V Reference Allows Low Output Voltages
- User Selectable Burst Mode® Operation or Forced Continuous Operation
- Output Voltage Tracking and Soft-Start Capability
- Short-Circuit Protected
- Overvoltage Input and Overtemperature Protection
- Power Good Status Outputs
- Available in (4mm × 5mm) QFN-28 and 28-Lead TSSOP Packages
The LTC3633A-2 is a high efficiency, dual-channel monolithic synchronous buck regulator using a controlled on-time, current mode architecture, with phase lockable switching frequency. The two channels can run 180° out of phase to relax the requirements for input and output capacitance. The operating supply voltage range is from 3.6V to 20V, making it suitable for lithium-ion battery stacks as well as point of load power supply applications from a 12V or 5V supply.
The operating frequency is programmable from 500kHz to 4MHz with an external resistor and may be synchronized to an external clock signal. The high frequency capability allows the use of small surface mount inductors and capacitors. The unique constant frequency/controlled on-time architecture is ideal for high step-down ratio applications that operate at high frequency while demanding fast transient response. An internal phase locked loop servos the on-time of the internal one-shot timer to match the frequency of the internal clock or an applied external clock.
The LTC3633A-2 can select between forced continuous mode and high efficiency Burst Mode operation. The LTC3633A-2 and LTC3633A-3 differ in their output voltage sense range (refer to Table 1 in the Operation section of the datasheet for a description of the entire LTC3633A product family).
|Part Number||Output Voltage Sense Range||SVin Input||V2P5 Output||LTC3633 Pin Compatible|
|LTC3633A||0.6V TO 6V||No||Yes||Yes|
|LTC3633A-1||1.5V TO 12V||No||Yes||Yes|
|LTC3633A-2||0.6V TO 6V||Yes||No||No|
|LTC3633A-3||1.5V TO 12V||Yes||No||No|
- Distributed Power Systems
- Battery Powered Instruments
- Point of Load Power Supplies
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 DC1896 is a dual output regulator consisting of two constant-frequency step-down converters, based on the LTC3633A-3 monolithic dual channel synchronous buck regulator. The DC1896 has an input voltage range of 3.6V to 20V, with each regulator capable of delivering up to 3A of output current. The DC1896 can operate in either Burst ModeÔ or forced continuous mode. In shutdown, the DC1896 can run off of less than 15 uA total. The DC1896 is a very efficient circuit: up to 90%.
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.
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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.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
LTC3633A-2 Companion Parts
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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.