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Low-profile voltage-regulator module connector saves space

San Jose, Calif. – Molex Inc. is coming to the Intel Developer Forum with what the company calls the industry's first low-profile voltage-regulator module (VRM) connector that permits vertically pluggable VRMs in 1U servers. The connector, designed to save board space, can also be used with small-form-factor PCs and workstations. The three-day Intel meeting begins here tomorrow.

The height of Molex's low-profile VRM connector is 0.342 of an inch compared with the traditional VRM connector height of 0.610 of an inch, said Jim McGrath, Molex's director of strategic products. The critical dimension is from the baseboard to the top of the VRM, which is 1.25 inches with the new low-profile connector, he said.

The problem with the taller connector, McGrath said, is that it didn't give the voltage-regulator module manufacturers enough board space to place their components. “With a lot of extra cost you could probably make a module that would work with the original connector but it's less expensive to design a module that would fit into a low-profile connector which gives them more board space,” he said.

Molex's so-called iCool connector, which incorporates a low loop-inductance design, was developed for high output currents at high slew rates. It's designed for VRM 10.0 applications including VRM 10.2. The connectors can handle up to 130 amps of output current in 4-inch connectors.

The connector, available in a vertical configuration with either a through-hole or SMT solder attachment, features an open housing design for air flow to cool the contacts. This provides a significant benefit in terms of current-carrying capability, McGrath said.

The connector industry has typically measured current rating by how much current the connector carries when the temperature of the contacts rises 30 degrees C, McGrath said. But OEMs said this doesn't mean anything, in the case of the VRM connectors, because the connectors could be in a 60 degrees C ambient environment with the VRM plugged into a heat sink with airflow, he added.

Therefore, the goal is to design a connector that will have a lifetime operating temperature rating to allow for an ambient temperature of 60 degrees C, plus the Joule heating of the contacts due to current, McGrath said. “The connector may also see some temperature rise from convection and conduction from the VRM itself which is also generating heat,” he said.

McGrath said testing by one VRM maker shows that the connector contacts are cooler than the copper traces on the VRM so by creating a design that keeps the connector contacts cooler than the VRM copper power planes, the iCool is providing additional thermal sinking for the VRM, which the air flow over the flat contacts in the open housing design facilitates.

Molex (Lisle, Ill.) rates the VRM connector at 105 degrees C operating temperature to provide for the combined temperatures of 60 degrees C ambient plus 30 degrees C temperature rise due to Joule heating and heat transfer from the VRM to the connector.

Other iCool connector features include fitting nails and a plastic-locating peg for the SMT version, selectively gold-plated contacts for electrical stability and four fork locks to secure the connector to the PC-board to resist shock and vibration. The connector is available with integral latches, which incorporate a unique reverse-angle latch notch in the VRM to help retain the module securely during shock testing, said the company.

Optional versions are available for 2U servers and larger platforms with ambient air temperatures up to 60 degrees C.

McGrath said VRM manufacturers are implementing modules for this connector and four power silicon manufacturers are developing low-profile module reference designs for the iCool connector in 1U applications. Prices for the iCool connector range from $2.50 to $3.50 depending on production volumes. Delivery is four to six weeks.

Call (800) 786-6539
http://www.molex.com/product/edgecard/icool.html

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