A couple weeks ago I had the opportunity to visit Texas Instruments’ high voltage dispatch office located in Dallas, Texas. This fully computer-controlled command center monitors loads at all Dallas-based wafer fabrication facilities. Completed in 2013, this state-of-the art control room monitors the power real-time and displays information on an entire wall of video screens. Before visiting, I envisioned the command center looking like a smaller version of the space shuttle’s mission control facility in Houston. But, there wasn’t a knob or a lever anywhere to be seen - just computer mice. Also, the amount of power being monitored was very impressive. Personally, I don’t feel comfortable around megawatt and kilovolts, and the most power I have ever dealt with is a 500W phase-shifted full-bridge converter using the UCD3138, which is a digital power controller with a PMBus™ interface.
PMBus is a standard way to communicate with power converters over a serial digital interface. Engineers have been using digital interfaces, such as an I2C or CAN bus, for decades, and the PMBus interface allows commands specifically suited for power management. One unique feature of PMBus is its ability to monitor and report current, voltage, and temperature without additional integrated circuits. AC/DC power supplies in telecom and computing applications have been using PMBus for a while since engineers really want to monitor these higher levels of power, just like the experts at the high voltage dispatch office.
The PMBus interface is quickly migrating into point-of-load applications. Texas Instruments recently announced new SWIFT™ DC/DC converters with integrated power MOSFETs. The TPS544B20 and TPS544C20 are the industry’s first high-current DC/DC converters with integrated FETs and a PMBus interface with monitoring and telemetry. They support a 4.5V to 18V input and supply 20A and 30A, respectively, and are available in a small 5x7mm QFN package that fits in space-constrained applications.
PMP9008 - 12Vin to 1V/30A Reference Design
Monitoring and telemetry are capabilities that can add a lot of value in many applications. Current products focus on monitoring output voltage, current, and temperature, but what other parameters would be useful to monitor?
Point-of-load applications with a PMBus interface can also benefit from data collection, live performance monitoring, system characterization during development, and failure analysis. Let us know how you could use telemetry in point of load applications.
How do you see the Power-One patent decision affecting the future of PMBus?
PMBus is royalty-free to the end-users. The power devices that use the PMBus interface help solve particular problems, add value to the end equipments, and are being more widely adopted. So, the decision doesn't seem to be affecting the adoption rate or the future of PMBus.
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