Tuesday, June 30, 2015

Using User Defined Statuses on the APS

Hi Everyone,

I wanted to talk about a feature in our Advanced Power Supply family (APS from here on out)  that not too many people know about.  The APS features two user defined statuses in the Operation Status group.  Here is a rundown of all the entries in the group:


You can see that bits 7 and 8 are User1 and User2.

Using the advanced triggering system for the APS you can define what conditions will trigger a change in these two statuses.  The N7906A Power Assistant Software (download link) has a very handy graphical way to set up the trigger.   As an example, let's say that I wanted to change the user defined status when the voltage exceeds 1 V and the unit goes into positive current limit status.  Using the Power Assistant Software I would whip up the following:


After I draw out my trigger expression, I can either download it to my APS or I can click the "SCPI to Clipboard" button on the top of the page.  If I hit that button now and then hit paste here, I get:

:SENSe:THReshold1:FUNCtion VOLTage
:SENSe:THReshold1:VOLTage 1
:SENSe:THReshold1:OPERation GT
:SYSTem:SIGNal:DEFine EXPRession1,"Thr1 AND CL+"
:STATus:OPERation:USER1:SOURce EXPRession1

I can just copy this code into my program.  It's a pretty convenient.

I think the big question is: What can you do with this?  The answer is: whatever you want.  It's user defined so you can use it in whatever way you see fit.  If you want to check if the current exceeds a certain threshold you don't want to do a bunch of measure commands in loop, you can define that as your trigger and then just check the Operation Status Group (using the STAT:OPER? or STAT:OPER:COND? queries). 

I think that the most powerful thing that you can do with this is set up a SRQ handler to act when the user statuses change.  This is actually a project that I am working on presently so I have not implemented this just yet (but I will in the near future).   When I do, I will definitely write a blog post about it though!  I wanted to get the word out about this because even I did not automatically think about this when faced with a issue that just screamed to use this.  

Thanks for reading and stay tuned for a future installment on this topic! 

  




Friday, June 19, 2015

How does your product react to a power line disturbance?

Power line disturbances can occur anywhere at any time. Your product can be exposed to disturbances such as voltage surges, sags, brownouts, cycle dropouts, or transients. If you are involved in the design, manufacture, or analysis of a power conversion product or circuit, you are interested in how your product reacts to power line disturbances because your product’s reaction will have a direct impact on how satisfied your customers are with the performance of your product. It is therefore critical for you to know how your product will react to power line disturbances. This knowledge comes only from direct measurement of the power line disturbance and the resultant behavior of your product.
Keysight’s IntegraVision power analyzer model PA2201A can allow you to gain quick insight into your product’s power consumption and dynamic behavior when it is exposed to power disturbances.
Next week, on Thursday, June 25, 2015, at 1:00 pm EDT, I will be presenting a live webinar on the topic “Successfully Make Power and AC Line Disturbance Measurements”. To get more information and to register to attend, please click this link: http://electronicdesign.com/webinar/successfully-make-power-and-ac-line-disturbance-measurements

If you are reading this BEFORE the webinar date, I hope you will attend the live presentation next week. If you are reading this AFTER the webinar date, the above link should bring you to a recording of the webinar.

Enjoy!

Tuesday, June 16, 2015

When is it best to use a battery or a power supply for testing my battery powered device?

As I do quite a bit of work with mobile battery powered devices I regularly post articles here on our “Watt’s Up?” blog about aspects on testing and optimizing battery life for these devices. As a matter of fact my posting from two weeks ago is about the webcast I will be doing this Thursday, June 18th: “Optimizing Battery Run and Charge Times of Today’s Mobile Wireless Devices”. That’s just two days away now!

With battery powered devices there are times it makes sense to use the device’s actual battery when performing testing and evaluation work to validate and gain insights on optimizing performance. In particular you will use the battery when performing a battery run-down test, to validate run-time. Providing you have a suitable test setup you can learn quite a few useful things beyond run-time that will give insights on how to better optimize your device’s performance and run-time. I go into a number of details about this in a previous posting of mine: “Zero-burden ammeter improves battery run-down and charge management testing of battery-powered devices”. If you are performing this kind of work you should find this posting useful.

However, there are other times when it makes sense to use a power supply in place of the device’s battery, to power up the device for the purpose of performing additional types of testing and evaluation work for optimizing the device’s performance. One major factor for this is the power supply can be directly set to specific levels which remain fixed for the desired duration. It eliminates the variability and difficulties of trying to do likewise with a battery, if at all possible. In most all instances it is important that the power supply provides the correct characteristics to properly emulate the battery. This includes:
  • Full two-quadrant operation for sourcing and sinking current and power
  • Programmable series resistance to simulate the battery’s ESR

These characteristics are depicted in the V-I graph in figure 1.


Figure 1: Battery emulator power supply output characteristics

Note that quadrant 1 operation is emulating when the battery is providing power to the device while quadrant 2 is emulating when the battery is being charge by the device.


A colleague here very recently had an article published that goes into a number of excellent reasons why and when it is advantageous to use a power supply in place of trying to use the actual battery, “Simulating a Battery with a Power Supply Reaps Benefits”. I believe you will find this to also be a useful reference.

Wednesday, June 3, 2015

Webcast this June 18th: Optimizing Battery Run and Charge Times of Today’s Mobile Wireless Devices

One thing for certain: Technological progress does not stand still for a moment and there is no place where this is any truer than for mobile wireless devices! Smart phones, tablets, and phablets have all but totally replaced yesterday’s mobile phones and other personal portable devices. They provide virtually unlimited information, connectivity, assistance, and all kinds of other capabilities anywhere and at any time.

However, as a consequence of all these greater capabilities and time spent being actively used is battery run time limitations. Battery run time is one of top dissatifiers of mobile device users. To help offset this manufacturers are incorporating considerably larger capacity batteries to get users through their day. I touched upon this several weeks ago with my earlier posting “Two New Keysight Source Measure Units (SMUs) for Battery Powered Device and Functional Test”. We developed higher power versions of our N678xA series SMUs in support of testing and development of these higher power mobile devices.

Ironically, a consequence of higher capacity batteries leads to worsening of another top user dissatifier, and that is battery charging time. Again, technological progress does not stand still! New specifications define higher power delivery over USB, which can be used to charge these mobile devices in less time. I also touched upon this just a few weeks ago with my posting “Updates to USB provide higher power and faster charging”. The power available over USB will no longer be the limiting factor on how long it takes to recharge a mobile device.

I have been doing a good amount of investigative work on these fronts which has lead me to put together a webcast “Optimizing Battery Run and Charge Times of Today’s Mobile Wireless Devices”. Here I will go into details about operation of these mobile devices during use and charging, and subsequent testing to validate and optimize their performance.  If you do development work on mobile devices, or even have a high level of curiosity, you may want to attend my webinar on June 18. Additional details about the webcast and registration are available at: “Click here for accessing webcast registration”. I hope you can make it!