Specifications

Synchronizing Output Turn-On and Turn-Off
Question: How can I synchronize different power supply outputs to turn on and off at the same time?
Answer: This can be a challenging problem because the products that could potentially be grouped together have
been designed over a period of 20 years. The availability of “hooks and handles” varies somewhat by series of
products. Also, there are some inherent limits as to how “simultaneously” products can react due to different power
supply topologies have different slew rates (i.e. the speed with which the output can change). Linear supplies
typically have slew rates in the 100’s of microseconds, while switching supplies respond in 100’s of milliseconds.
In the most general case, the majority of Agilent power products offer RI/DFI (remote inhibit/discrete fault
interrupt). This feature can be used to turn products off simultaneously, either as a result of a specific power supply
fault, using the DFI signal, or due to some external event, by pulling the RI contact low. Refer to the manual for your
product for additional information on how to accomplish this. On most products, the RI contact is a latching
function. Therefore to turn the products on, once RI has been activated, RI needs to be converted to non-latching.
While this capability is standard on the 661xA and 663xB products, it requires a special option, S50, on other series.
Contact your Field Engineer to find out about the availability of this option for your product. External components
such as relays, or FET switches are also required to control multiple power supplies.
For groups of products which all have SCPI command language, the group execute trigger (GET) command can be
used. However, timing accuracy is limited by command processing time which can be up to 50 milliseconds.
Furthermore, this approach cannot be used with power products that offer sub-addressing. See the programming
guide for your product family (available elsewhere on this website) for more information on <*TRG> and
commands. Also, refer to “IEEE Standard Codes, Formats, Protocols, and Common Commands”, IEEE STD 488.2-
1992 available from the IEEE.
One more alternative is available for systems composed of 66000 modular power system modules and 68xxB ac
sources. These products have expanded feature sets, which include “list and trigger” capabilities. These features
make it easier to synchronize or sequence power products. For more information, refer to Product Notes 5091-2497
and 5963-7044 for 66000 and 68xxA products respectively, which can be found using the search button in the upper
left corner of this website.