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TestScripts for Power Sources

How can a power source control a complex test procedure?

Test applications in development and manufacturing often require programmable power sources. These are intended to automatically run a complex pattern of precisely defined voltage and current loads. Doing so can require expensive hardware and take a lot of time. Intelligent power sources, which execute a script by themselves, allow complicated sampling patterns at a low price. The range of application of this method is conceivably large, for example rise time control for aging tests of components, staircase shapes for triggering thresholds of fuses and much more.

The following article shows how easy and at the same time how powerful the scripting method can be. It  gives a brief introduction to scripting. Some practical examples will be shown.

Advantages of a power source with script support

There are several classic approaches to running complex waveforms automatically. One of them is, for example, to connect the power source via an interface e.g. USB or LAN to an external PC. A manufacturer-provided or self-created test program then controls the power source. The use of a scriptural power source, in contrast, has the following particular advantages:

  • No programming skills are required. Focus on the power source. You do not need to use a programming language like C #.
  • The script is very fast and intuitive to understand. If you understand the functions and parameters of the power source, you will be able to cope with the format used in the script.
  • The automatic discharges are executed by the power source itself. There is no additional external PC controller required to run the script.
  • To create a script you just need a PC with Excel. Advanced Excel skills are not required.
  • Scripts that have been tested and managed in the function can easily be distributed to multiple test stations, which means more power sources.
  • A quick change of types of promotions is supported. Simply select the script you have prepared appropriately on the front panel of the device.
  • Very expensive power sources, e.g. with ARB function, or expensive interfaces e.g. GPIB can be avoided.

Creation of a Script

To get into the structure of a script, a fictitious test signal should first be generated. You can see how intuitive the idea of this method is. In a later chapter, we outline five practical examples.

The signal should look as shown below: there is a cycle that is repeated twice. The levels of current and voltage are independent of each other. A cycle consists of 9 different levels that change step by step.

Example of a test signal

This test signal is generated by the script below. In order to make it easier for beginners, the table has been reduced to the most important columns. The script essentially consists of two sections, a header (marked green) and a data block (marked in yellow) with the following function:

Header

The script has a header in lines 1 and 2. Here, the number of cycles selected is specified: Cycle Number is therefore 2. Depending on the number of 9 steps (9 values) within a cycle, the beginning and the end of the header are also displayed Entered at the end of the cycle: Start Step = 1 and End Step = 9. The header also handles other modes such as Loops that are not discussed here.

Data Block

The header follows in the form of a "Lookup Table" the payload for the cycle. Corresponding to the number of 9 levels within a cycle, the data block in the basic structure thus has 9 lines (step) which are shown in lines 5 to 13. Parameters of the settings follow these steps through the table columns. Refer to the headings in line 4 for this purpose. This includes the activation of the output, the duration of the level, voltage or current and others (not shown here).

This can then be read as follows: In line 5, the output remains off for 2 seconds. In line 6, the output is turned on and the voltage is set to 80 volts and the current is limited to 7 amperes.

  A B C D E F
1 CycleItems Number Start Step End Step    
2 Cycle 2 1 9    
3            
4 Step Point Output Time(sec) Voltage (V) Current (A)
5 1 Start Off 2 0 0
6 2   On 10 80 7
7 3   On 3 20 3.5
8 4   On 5 75 8
9 5   On 2 30 10
10 6   On 4 45 10
11 7   On 2 50 10
12 8   On 1 10 10
13 9 End On 5 70 20

Further Parameters in the Data Block

The data block contains further columns which control additional parameters of the current source in the current step. Such parameters are usually known in the industry or explained in the manual. Here is a short overview to illustrate that control of the script is extensively possible:

Name Funktion Wert
OVP(V) Over Voltage Protection MAX,1 MIN or value in V
OCP(A) Over Current Protection MAX, MIN or value in A
Bleeder Fast discharge of unit under test ON, OFF
IV Mode Mode Slope I/U

For maximum slope (rise and fall time are ignored) 

  • CVHS constant voltage
  • CCHS constant amperage

For specified slope (rise and fall time are used)

  • CVHS constant voltage
  • CCHS constant amperage
Vsr up(V/ms) Risetime Voltage MAX or value in V/ms
Vsr down(V/ms) Falltime Voltage MAX or value in V/ms
Isr up(A/ms) Risetime Amperage MAX or value in A/ms
Isr down(A/ms) Falltime Amperage MAX or value in A/ms
Jump to Destination of Jump Stepnumber within the payload
Jump cnt Jump Count Count of jump repetitions

Loading and Using the Script

The finished script is saved on a USB stick and plugged into the USB port of the power source. The front panel of the power source allows the handling of the scripts through the standard buttons and displays (normally used for the setting / display of voltage / current). This involves placing the script inside the power source in one of the ten available script stores and enabling already dropped scripts.

Storage of the script within the script memory

For example, the following figure shows that the script is in the wait state. If the normal activation key is pressed for the output then the script is started.

Power source is waiting for signaling to start script

Support for Correct Entry

To help you get there fast, the power source helps to set up the scripts correctly. In the event that a syntax error has crept into the table, it will be displayed on the front panel. A suitable report can be picked up via the USB stick. The following pictures show an example.

Report file is available after filing a script Identification number gives assistance

It is the identification number 93. The report is filed as a CSV file and contains a short explanation. In this case, "93 _SEQ_ERR__OCP_TOO_SMALL". This means that the value entered for the overvoltage protection is too small.

Tip: The different script stores can be used many times:

  • When writing the script to debug settings to find the optimal probing and parameterization.
  • To set up different test scenarios on a particular flyer. For example, a quick test and only if it has worked, then a endurance test.
  • Allow quick change of different types of test on a single test station.

Example Scripts

Example 1: Test Script for Pulse Output

Settings: Set and execute a pattern that switches 12V/1sec to 5V/1sec for 6 times with the current setting of 3A.

Intended Signal Screenshot Oscilloscope

Script

Example 2: Test Script for Aging Test with a controlled Rise Time

The output voltage rises from 0V to 5V in 50 seconds at current setting of 10A and maintains the settings for 30 minutes and then output is turned off automatically.

Intended Signal Screenshot Oscilloscope

Script

Example 3: Test Script to generate Burst Noise

The graphic shows the ideal waveform. However, the waveform depends on the voltage setting and the bandwidth of the current source used. Burst signals are applied in the middle of the constant voltage. The example shows a continuous output voltage that produces a burst pulse between 12V and 8V. Each burst signal is 100ms and the total duration of the burst signals is 1.5s. It occurs every 10 minutes (600s).

Intended Signal Screenshot Oscilloscope

Script

Example 4: Test Script for Lifetime Test

For durability tests such as lights, heaters, etc., pattern that repeats for 18-hour output on and 6-hour output off for 100 days is as follows.

Intended Signal Screenshot Oscilloscope

Script

Example 5: Test Script for Testing Resettable PPTC Fuses

A test example for a resettable PPTC fuse checks the open circuit properties by increasing current from 0 to 3A in 16-step resolution. The test script simply executes a sequence of different constant voltage setting currents to test the properties of a PPTC fuse when it is triggered and reset.

Intended Signal Screenshot Oscilloscope

Script

Power Sources that support Scripts

Further information can be found at StanTronic. We are happy to send you script examples for your scriptable GW Instek power source. If you are planning an acquisition we advise you to find the right device for your application.

PSU Serie
1 Channel
Rack Mount 1HU
PSW Serie
1 Channel
PSB Serie
Multichannel
PFR Serie
1 Channel
GW-INSTEK-GW-PSU 100-15 GW-INSTEK-GW-PSW 160-14.4 GW-INSTEK-GW-PSB 1800L GW-INSTEK-GW-PFR-100M

PSU 6-200

PSU 12.5-120

PSU 20-76

PSU 40-38

PSU 60-25

PSU 100-15

PSU 150-10

PSU 300-5

PSU 400-3.8

PSU 600-2.6

PSW 30-36

PSW 30-72

PSW 30-108

PSW 80-13.5

PSW 80-27

PSW 80-40.5

PSW 160-7.2

PSW 160-14.4

PSW 160-21.6

PSW 250-4.5

PSW 250-9

PSW 250-13.5

PSW 800-1.44

PSW 800-2.88

PSW 800-4.32

PSB-1400L

PSB-1400M

PSB-1800L

PSB-1800M

PFR-100L

PFR-100M

 

 
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