How to Create Power Supply Output Sequences with Data Logging
When using a triple-output power supply, it is often risky to turn on all the outputs. Many devices need to be powered up in a very specific order, or you could damage them. To resolve this issue many devices require multiple bias or rail voltages. Devices such as field programmable gate arrays require the voltages to turn on and off in a set sequence.
If you are working with devices that have specific timing requirements, you will want to use a power supply with power sequencing. Power supply sequencing enables you to automatically set voltage outputs and delays according to a pre-scripted pattern of your choosing. You can avoid accidental damage by using power supply sequencing; you will no longer need to turn on different channels manually or set output voltages manually.
This blog post will explain how to create power supply output sequences with data logging using the Keysight E36312A / E36313A power supply.
The Importance of Sequencing
Devices such as microprocessors, field programmable gate arrays, and complex circuits require the voltages to turn on and off in sequence. Power supply sequencing enables you to automatically set voltage outputs and delays according to a pre-scripted pattern of your choosing. Not only is power-up sequencing important, but power-down sequencing can help ensure proper shutdown of your device under test (DUT).
Sequencing test setups can be challenging when you try to synchronize individual independent multiple power outputs. The Keysight E36312A and E36313A triple-output bench power supply with built-in voltage sequencing capabilities offer the user precise control over power-up and power-down sequences. The bench power supply enables users to create a single DC output sequence on one channel or group of channels, with up to three DC outputs in the sequence.
Power Up and Power Down Sequences Setup
Figure 1 shows an example of a power-on and power-off sequence using a complex circuit board and the Keysight E36313A.
Figure 1. Keysight E36313A connects to power-up a circuit board
To generate all three E36313A DC outputs, the first step is to set up each output for the correct voltage and current limit. Each of the E36313A power supply’s three outputs are independent and isolated, so it is easy to set the voltages and not worry about having a common ground. First, set Channel 1 to 5V, Channel 2 to 15V, and Channel 3 to 20V.
Next, set the delays. You can configure On Delay and Off Delay for each channel. The On Delay function represents how long the unit waits to turn on after you start the sequence. The Off Delay represents how long the unit waits once you initiate the end of the sequence. For the power-up sequence, you program Channel 1 for a one-second delay, Channel 2 for a three-second delay, and Channel 3 for a five-second delay.
For the power-down sequence, you reverse the order and set Channel 3 to 0V, Channel 2 to 0V, and Channel 1 to 0V. Channel 3 gets a one-second delay, Channel 2 has a two-second delay, and Channel 1 gets a three-second delay.
Now you can start the sequence and data logger by pressing the All On / Off key. Wait about 10 seconds and then initiate the power-down sequence using the All On / Off key and wait for the data logger to finish recording.
Capturing Voltage and Current Measurements Using Data Logging
The data logger enables you to record voltage and current pairs over time. When the data logger capability is integrated into the power supply, you eliminate the need to add a second instrument to the test setup specifically for data logging.
How to Set Up Data Logging in 5 Easy Steps
Step 1: Determine the number of channels, voltage sequence, and delay times for each output channel.
Step 2: Set up each channel voltage and the current limit settings.
Program Channel 1 for 5V, Channel 2 for 15V, and Channel 3 for 20V. In the example in Figure 2, you see the default current limit settings.
Figure 2. Channel voltage and current limit setting
Step 3: Configure the channel turn-on and turn-off delays, then join the outputs together.
Use the On / Off Coupling button to set all three channels to On. In Figure 3, all three channels appear coupled in the sequence and respond to the trigger command using the front panel with all On / Off keys.
Figure 3. The channel turn-on and turn-off delay setting
Step 4: Set up the data logger properties and waveform settings.
Select the channels you want to see; in our example, we selected V1, V2, and V3. Next, program the data logger selections, the duration for the data capture, the sample period, and the trigger source that appears in Figure 4. The data file size automatically calculates based on the settings. When performing a data log, connect a USB drive to the front-panel USB port to store the data log.
For the next three steps, start with the data logger, then initiate the power-up sequence trigger, wait a few seconds, initiate the power-down sequence, and wait until the data logger finishes recording.
Figure 4. Data logger and waveform set
Step 5: Start the data logger by pressing the Run / Stop key, then press the Back key.
Start the power-up sequence by pressing the front panel All On / Off key, wait for about 10 seconds, then press the front panel All On / Off key again to initiate the power-off sequence.
The data logger captures all three DC outputs and displays the power-up and power-down voltage sequence that appears in Figure 5.
Figure 5. Three DC outputs and displays of the power-up and power-down voltage sequence.
Summary
Bench power supplies have a built-in output sequencing function that enables programmability. By using the test sequence feature, you can program voltage values, current limit values, and time per step. Using the bench power supply with the test sequences feature enables precise control over power-up and power-down sequences and reduces test setup complexity.
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