Linear’s Dual 13A or Single 26A DC/DC µModule Step-Down Regulator with Integrated Heat Sink Delivers up to 100A
Darnell interviewed Afshin Odabaee, Product Marketing Manager, DC/DC µModule Products at Linear Technology Corporation, who talked through Linear Technology Corporation's launch of the LTM4620, a dual 13A per output or single 26A output DC/DC µModule® step-down regulator that delivers up to 100A when four devices are current shared. The LTM4620 is a complete DC/DC regulator system in a space-saving 15mm x 15mm x 4.41mm LGA package which has the benefit of including inductors, power stages and all control circuits. Everything is taken care of for the discerning designer who wants a part that does just what the specification says, and works right-first-time. The LTM4620 is a real game changer, solving several difficult power, space and heat challenges for system designers so they can migrate to denser or computationally more powerful PCB and circuits. The LTM4620 is smaller and much simpler to work with than its equivalent discrete solution and is a more powerful solution, requiring only half the area of other encapsulated DC/DC regulator modules available on the market today.
For optimum heat dissipation, a patented top side heat sink removes heat quickly and evenly in this extra thermally enhanced package. With 200LFM air flow, 12VIN to 1.0VOUT and at full load of 26A (or 13A per output), the LTM4620 internal temperature rises only 60°C above ambient. With the addition of an external heat sink to the top of the package and 200LFM air flow, the temperature rise is only 40°C. Many new Innovations and smart design practices are the reasons for the LTM4620's outstanding thermal performance, all of which are key drivers for the designer or developer who needs a compact yet powerful solution within a thermally-challenged project:
* Eliminate wire bonds from four MOSFETs (2 MOSFETs per channel)
* Extra copper in substrate
* Latest DC/DC controller with powerful gate drivers
* Clever layout for uniform heat spread
* Integrated onboard heat sink transfers heat from MOSFETs and inductor to top of package
See Linear's TechClip video at http://video.linear.com/p4634 for a performance demonstration.
The LTM4620 is designed to convert 5V to 12V inputs to high power, low voltage point-of-load system rails such as 2.5V to as low as 0.6V. An accurate reference and an internal remote sense amplifier guarantee +/-1.5% accurate output regulation over line, load and temperature. Sensing the voltage at the load compensates for voltage drops caused by PCB trace impedance. Excellent heat dissipation, low temperature rise, scalable and high output power capability, small footprint and the low profile package of the LTM4620 enable system designers to lay out more densely populated boards. Applications include mezzanine boards such as ATCA and microTCA systems, point-of-load regulation for advanced processors, ASICs and recently introduced 28nm FPGAs as well as high-speed SERDES.
LTM4620 Simplified Schematic
The LTM4620 features fast short-circuit protection where a current foldback technique reduces IOUT to a minimum, preventing the µModule regulator from overheating while protecting the load as well as the upstream power supply. Once the short-circuit condition is removed, the LTM4620 resumes operation (see TechClip video demonstration)http://video.linear.com/p4634
The two outputs of the LTM4620 operate at 180° out of phase to minimize output ripple (when outputs share current) and input ripple, resulting in the use of fewer and smaller capacitors.
LTM4620 Summary of Features:
* Dual 13A or Single 26A Output
* Multiphase Current Sharing with Multiple LTM4620s up to 100A
* Wide Input Voltage Range: 4.5V to 16V
* Output Voltage Range: 0.6V to 2.5V
* ±1.5% Maximum Total DC Output Error
* Differential Remote Sense Amplifier
* Current-Mode Control/Fast Transient Response
* Overcurrent Foldback Protection & Output Overvoltage Protection
* Adjustable, Synchronizable Switching Frequency
* Internal Temperature Sensing Diode Output
* Low Profile (15mm x 15mm x 4.41mm) LGA Package
For a 100A design, four LTM4620 devices accurately current share and operate at 90° out of phase. The LTM4620 is rated for operation from -40°C to 125°C. 1,000-piece pricing starts at $29.99 each. For more detailed information on this product, visit http://www.linear.com/product/LTM4620.
