Software and Power, No Longer Separated
By David Norton, Lambda
The use of software with a power supply has been restricted until recently, to small sections of the electronics industry. The idea of adding features and hence cost, to one of the already highest dollar value items on a designer's bill of materials would have been unimaginable.
The high end of complexity has always been the traditional programmable power supply mainly used in test and measurement applications. With wide output adjustment, capability of operating in both constant voltage or constant current modes, and containing RS232 or GPIB interfaces, these products have been the only solution for many designers.
The ability to software control the output voltage adjustment allows automatic testing, to ensure that the device under test can not only cope with the extremes of DC input line changes, but to simulate extensive life cycling under a controlled manner.
For process control applications where uptime is critical, 24 V & 48 V DC hot swap N+1 rectifiers used for telecom battery plants and front ends for Distributed Power Architecture (DPA), are being shipped with an increased level of software.
Previously limited to the rudimentary feature set of a battery charger, these "bulk" power supplies now communicate via software to provide a host of remote diagnostics and programming capabilities normally found on more expensive equipment. The user can determine the amount of current being drawn and get advanced notice of any impending fan failure or over temperature conditions. In addition, the user can program output voltages and change the over current characteristics to suit the load needs.
The 450 W and 650 W Vega Series is being enhanced with a microprocessor control option. This feature offers low volume users the ability to provide a system feature normally found on high-end systems.
During the development testing stage, the ability to log and read back actual currents drawn by the load enables the designer to save time during testing, by knowing that the power supply is correctly rated for the application. "Vega Smart" has a monitor screen application that can visually display the outputs and status of the signals.
During testing, it may be determined that a lower power configuration could be used, reducing component cost. Once testing is complete, the non-software power supply can be substituted further reducing cost.
If a non-standard configuration for sequencing is necessary on the Vega Series, a reduced feature set can be offered, without the communications access consisting of just the EEPROM controlled modules.
At the Factory Adding a simple serial EEPROM can reduce configuration costs. System configuration control usually mandates that the power supply's serial number, revision level, and date code is recorded. That operation can be automated and stored electronically. The configuration record can also be maintained accurately if a power supply is swapped out during field maintenance.
Inventory and the need for (long lead-time) special order parts can be reduced. Standard TL Series units can be purchased through distribution and configured using the internal EEPROMs during the production process for non-standard voltage and current characteristics. This reduces the number of SKUs being purchased and one part will now fit many solutions.
In the Field Once a system is deployed in the field and the user requests an upgrade, a remote interrogation can determine how much current the power supply is currently delivering. This will determine if a second or larger unit is needed to support the upgrade. It allows the field person to have the appropriate parts on hand, reducing service costs.
Fan replacement maintenance can be scaled back, using either the fan or actual system run time diagnostics from the power supply.
Implementation of remote access via "dial up" or the Internet can eliminate the service call altogether. Detailed diagnostics from the supply can allow a more thorough evaluation of the system. Output voltages may be "tweaked" to optimize performance or resolve faults.
The challenge to the power supply companies will be this addition to the skill set of their employees. U.S.-based companies with a strong support staff will obtain an advantage over some of the low cost, low overhead offshore companies. Web based support will also be critical, and power supply companies will soon be seen posting driver updates.
Engineers are starting to see the possibilities of combining software and power. Perhaps the long-standing complaint that the power supply is the "last item to be considered" may begin to change.