The top side of a typical system board such as a PCI-E card is densely populated with FPGAs, ASICs, microprocessors, transceivers, connectors, memory ICs, and DC-DC regulators while the backside is often unused.
The top side of a typical system board such as a PCI-E card is densely populated with FPGAs, ASICs, microprocessors, transceivers, connectors, memory ICs, and DC-DC regulators while the backside is often unused. This is a common side effect of the significant difference in top versus backside height restrictions where board specifications may allow topside device to reach a few centimeters but restrict backside package to less than 2.3 millimeter. What if functions usually found on the top side, such as a DC-DC regulator circuits, can be thinner and moved to the bottom?
Even better, what if four DC-DC regulator circuits could be compacted, fitting into a 9-millimeter by 15-millimeter footprint package with only 1.82 millimeter height? This allows for a 73% smaller solution size with 79% fewer components.
Transcript below
Hello, my name is Richard Ying, a design engineer for the Micromodule Power Product at Analog Devices' Power by Linear. I'll be introducing the LTM4643, a quad 3amp output micromodule regulator belonging to the family of ultrathin micromodule packages, which range in the package height from 1.82 millimeter to 1.91 millimeter.
Here is a view of the ultrathin micromodule products. Look at the side view of the package. The package height ranges from 1.82 millimeter to 1.91 millimeter with the LTM4643 as the newest member to the family. In a 9 millimeter by 15 millimeter LGA package with only 1.82 millimeter
package height.
The LTM4643 has four 3M DC-DC regulator circuits within the package, including the inductors, DC-DC regulator ICs, power FETs as well as supporting components such as resistors, diodes, and bypass capacitors. The LTM4643 and the rest of the ultrathin micromodule regulators benefit system designs in several ways.
One benefit is that the ultrathin package allows for the placement of the regulator circuits in previously unused board areas. Some applications such as PCI-E board, rack mounted communication products or RAIDs have board to board distance and/or component hide restrictions. Many PCI-E boards, for example, do not allow a component height above 2.3 millimeter on the backside of the PCB.
The LTM4643 and ultrathin micromodule regulators are thin enough to fit on the backside of this PCBs allowing system engineers to move point of load regulators away from the top of the PCB, thus creating more space on the top side of the PCB for more memory, larger FPGAs, additional connects, and so on.
Another benefit is in applications using a heatsink or liquid cold plate. In some cases, digital devices, like FPGAs or processors require a heatsink or liquid cold plate. This puts a hard limitation on components within the area covered by the heating which can lead to loss of precious board spaces when device cannot be fine to meet the high restrictions.
The package height of the ultrathin micromodule regulator is similar to these kind of digital devices, allowing the micromodule regulator circuits to be mounted close to these digital devices, even under a common heatsink. The LTM4643 is a new member of the ultrathin micromodule regulator family.
It is a quad step down switching regulator. The input voltage range is 4 volt to 20 volt, and the output voltage range is 0.6 volt to 3.3 volt. Each output can deliver up to 3amp, designing with the LTM4643 is easy, requiring only input capacitors, and for each channel, an output capacitor and resistor to set the upper voltage.
The package size is 9 millimeter by 15 millimeter with few external components. The circuit is simple and the solution size is small. The outstanding feature of the LTM4643 is 1.82 millimeter of the package height. It can be mounted on the backside of the PCB or under the heating.
Another unique feature of the LTM4643 is flexibility of the configuration of the output. Due to its excellent current sharing capability, it can be configured for more than just four separate 3amp outputs. It can be configured for many other real combinations such as a triple output configuration, where two of the phases are tied together, a dual output were two pairs of the phases are tied together, or a single 12amp output where all four phases are tied together.
The LTM4643 is packaged in a rectangular form factor. This provides more freedom for the PCB layout designs, allowing for either widthwise or lengthwise placement. The ultrathin micromodule regulator family lineup includes the LTM4623, a single 3amp regulator, the LTM4622, a dual 2.5amp or 5amp parallel regulator. The LTM4631, a dual 10amp or 20amp parallel regulator.
The LTM4643, a quad 3amp or 12amp parallel regulator. And the LTM4632, a triple output regulator for DDR applications. We provide a selector table of this product, data sheets, and other information on the website.
Thank you for watching.
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