Electronic Design

Choose The Right Power Distribution For Your Multi-Device Kiosk Environment

Power distribution considerations become critical infrastructure decisions in environments where hard use and high-reliability requirements meet. Sometimes separate power supplies are required for driving multiple devices in a multi-user kiosk application, and sometimes such a system can be served by using a flexible power distribution method.

For example, one casino customer needed to drive multiple thermal printers used in the customer tracking system integrated into its gaming machines. Slot machines and other gambling devices don’t give out quarters anymore. They give out paper. These printers needed to serve both gambling and non-gambling customer systems to deliver receipts, coupons, and other hard-copy materials to customers around the clock.

The first thought might be to simply run a tap off of the served machine’s power supply for the printers. But that approach has a lot of problems, primarily involving the system power budget, product performance, and security.

Power Budget

Designers of gambling devices and video games specify a power supply for them with a total system consumption in mind, and it usually doesn’t have much leeway in the area of continuous power to attach a peripheral device drawing anywhere from 10 to 15 W. Some systems may have generous surge power margins, but you can’t use surge power to drive a current-needy peripheral.

The other major issue would be device security, as you can’t simply reach into the guts of a licensed gambling machine at whim without opening a Pandora’s box of issues from electronic interference changing probabilities in the device to regulatory issues of access to the system’s electronics.

Once the need to bring in an external (embedded in the cabinet or external to the system entirely) supply to power the printers became apparent, the question shifted to the nature of the supply and how to reduce cost in the face of the need to add major components to the mix.

The customer initially requested a modified standard supply with multiple output cords (four), which would have required safety re-submittals for the supply as well as tooling, packaging, strain relief, and cable costs (five figures). An in-line power distribution box solution was proposed, as the box would be on the low-voltage side of the power chain and therefore would not require safety re-submittals.

Dividing It All Up

GlobTek chose to use one supply for every three printers and the GT-21097-5024 Power Divider to provide reliable scalable power independent of the primary device supply. This enabled the use of standard printer power connectors and cables, further reducing the cost and complexity of the solution. Additionally, we were able to use off-the-shelf power supplies with no additional tooling or package reconfiguration needed.

The resulting configuration also minimizes system cost and eases repairs and replacement in the field, and safety and reliability can be added easily by placing a resettable fuse at each output in the distribution block. In a pinch the distribution boxes can be used as line extenders in unusual deployment situations or field-expedient repairs without compromising system safety and reliability as well.

The resulting solution was able to directly address all of the customer requirements without having to go to specialty power supplies with multiple outputs that would have required additional approvals. This case demonstrated that many problems could be easily addressed with a little “out of the box” thinking and by looking at other parts of the power chain for the solution.

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