Showing posts with label discrete fault indicator. Show all posts
Showing posts with label discrete fault indicator. Show all posts

Tuesday, August 5, 2014

Upcoming Seminar on Protecting Your Device against Power-Related Damage during Test

Here on “Watt’s Up?” we have provided a good number of posts about various protection features incorporated into system power supplies to protect your device against power-related damage during test. Just recently my colleague Gary posted “How Does Power Supply Over-Voltage Work?” (Click here to review) Here he reviews inner workings of different OVP implementations.  I recently posted “Safeguarding Your Power-Sensitive DUTs against an Over-Power Condition” (Click here to review) Here I go over a method to protect your DUT against excess power when other power supply features like over current protection may be less than ideal.

The reason why we frequently share power-related protection topics here is protecting your DUT is extremely important, there are a lot of different capabilities incorporated in system power supplies for this purpose, and there are a lot of practical considerations when putting them to use.  

Hopefully a number of you have found our posts on protection-related topics of help. Because this is a very important topic and there is so much more you should know about it I will be giving a live web-based seminar “Protecting Your Device against Power-Related Damage during Test” on August 20th, just a few weeks away from today. I will be going over a number of protection-related topics which we have not yet covered here on “Watt’s Up?”.  One of my objectives is to provide a more holistic view of the many ways a system power supply is able to better safeguard against power-related damage as well as what is practical to expect when using these various capabilities incorporated in the power supply.

You can register online at the following (Click here for description and registration page) In case you are not able to attend the live event on August 20 you will be able to register and listen to seminar afterward as well, as it will be recorded.


So if protecting your device against power-related damage is important to you I hope you are able to attend the seminar!

Friday, February 8, 2013

Protecting your DUT using a power supply’s remote inhibit and fault indicator features


Paramount in most any good electronic test system is the need to adequately protect the device under test (DUT), as well as the test equipment, from inadvertent damage due to possible faults with the yet-untested DUT, accidental misconnections, misapplication of power, and a large number of other unanticipated events that can occur. It is no surprise that a lot of these unanticipated events by nature are related to the powering of the DUT. For this reason good system DC power supplies incorporate a number of features designed to protect both the DUT, as well as the power supply, in the event of an unanticipated fault occurring.  Two related protection features incorporated into our DC system power supplies are the remote inhibit and the discrete fault indicator (RI/DFI). These features provide real-time protection enabling immediate shutting down the power supply, as well as enabling the power supply to take immediate action, on the event of detecting the occurrence of an unanticipated event or fault.

The remote inhibit is a digital input control while the discrete fault indicator is a digital output control signal, incorporated into the digital I/O port on our system DC power supplies. An example of a digital I/O port is illustrated in Figure 1. When the digital I/O port is configured for fault/inhibit (also called RI/DFI) pins 1 and 2 are the open collector and emitter of an isolated transistor, to serve as a digital output control, and pin3 and 4 are the digital input and common for the inhibit control input. The remote inhibit and the fault indicator can be used independently as well as in combination, for protecting the DUT.




Figure 1: Multi-function digital I/O port on Agilent 6600A series system DC power supplies

As the name implies, the remote inhibit is a digital control input, when activated, immediately disables the DC power supply’s output. One way this is commonly used is to connect an emergency shutdown switch that can be conveniently activated in the event of a problem. This may be a large pushbutton, or it may be a switch incorporated into a fixture safety cover. This arrangement is shown in Figure 2.



Figure 2: Remote inhibit using external switch

The fault indicator (i.e. FLT, FI, or DFI) digital output signal originates from the system DC power supply’s status system. The status system is a configurable logic system within the power supply having a number of registers that keep track of its status for operational, questionable, and standard events. Many of these events can be logically OR’ed together as needed to provide a fault output signal when particular, typically unanticipated, events occurs with the power supply. Items tracked by questionable status group register, like over voltage and over current, for example, are commonly selected and used for generating a fault output signal. An overview of the power supply status register system was discussed by a colleague in a previous posting. If you are interested in learning more; click here.
The fault indicator output can in turn be used to control an external activity for protecting the DUT, such as opening a disconnect relay to isolate the DUT, as one example, as depicted in Figure 3.




Figure 3: Fault output controlling an external disconnect relay

For DUTs that require multiple bias voltage inputs it is usually desirable that if a fault is detected on one bias input, that the other bias inputs are immediately shut down in conjunction with the one detecting a fault. The fault outputs and remote inhibit inputs on several DC power supplies can be used in combination by chaining them together, as depicted in Figure 4, to accomplish this task, to safeguard the DUT.



Figure 4: Chaining fault indicators and remote inhibits on multiple DC power supplies

The remote inhibit and fault indicator digital control signals on system DC power supplies provide a number of ways to disable power and take other actions for safeguarding the DUT. Their action is immediate, not requiring communication to, and intervention from, the test system controller. At the same time the system DC power supply generates status signals and can issue a service request (SRQ) to the test system controller so that it is notified of a problem condition and take appropriate correction action as well. The remote inhibit and fault indicator digital control signals are just two of many features found in many good system DC power supplies to assure the DUT is always adequately protected during test!