When choosing an analog measurement transducer for a variety of instrumentation monitoring applications including machine monitoring, quality assurance, and more, you will be given a choice of signal types.
The most common signals for these transducers are either voltage (0-5 volts DC, or 0-10 volts DC) or current (generally 4-20 milliamps). Both types are low-cost and easy to find, and both have advantages and disadvantages depending on the environment in which they are being used.
Applications Specialists at CAS DataLoggers explore both the pros and cons of these two analog signals.
DC Voltage (0-5v, 0-10V) DC voltage is a very basic analog signal which gives you excellent resolution, is easy to connect and troubleshoot, and is well suited to lab environments. The sensors which use a voltage output tend to be quick and easy to connect. They require an input excitation voltage and have an easy to identify output wire carrying the measured signal.
However, a voltage signal is not a good fit if you are planning on using it in an industrial environment. Even when using shielded wire, the signal is highly susceptible to interference from high voltage AC, motors, pumps, relays, etc. The signal is also susceptible to voltage drops on log runs of signal wire.
DC Current (4-20mA) In contrast, a DC current loop offers several advantages in industrial settings. This signal is not as susceptible to electrical interference from high voltage AC, motors, pumps, or relays, nor is it susceptible to signal loss due to the length of the wiring run (voltage drop). A 4-20mA loop can also power multiple devices using one excitation source and requires much fewer wires. Additionally, a 4-20 mA signal offers fairly easy fault detection because its ‘0’ point is at 4mA, so if a negative reading is shown in the scaled readings, there’s likely a problem with the signal.
However, a 4-20mA signal will not give you the same resolution as a voltage signal so it is not necessarily recommended for use in a lab environment. Another drawback of a 4-20mA signal is that you will generally require shunt resistors to take a reading on most data logging equipment.
While there are many other considerations to take into account when choosing a transducer, environment and signal distance should be your main factors.
This outline will hopefully have given you a good basis for the best signal choice between voltage and current.
If you have worked in the semiconductor industry for more than a few years I am sure you have heard senior leadership speak about the need for your integrated circuit designs to be first pass successes and not the typical two to three spins or more to reach the targeted performance. The question is this: Is first pass success feasible and should be expected? I do not want to stir up a hornets nest with my response but the answer to the question is that it depends. Depends on what you say? Well, the answer depends on several different interwoven complexities that can determine if first pass success is possible. I would like to explore some possible ways to answer this question. Furthermore, the complexity of this question increases when developing complex mixed signal IC’s.
Fortunately for circuit designers, a new tool is available that can simplify the process of identifying the ESD suppression device best suited to an application, which makes it far easier to incorporate circuit protection earlier in the board planning process. The Littelfuse iDesign™ Online Simulation and Product Selection Tool
. I received a very good reader question from my last blog post regarding the various parameters that are reported by the tool. Let’s take a look at an example and explore the parameters that are returned. In this example we will look at the AD9643-250.
Managing system thermal performance is critical in today’s electronic systems if you are to maximize performance and the user experience. As systems grow more powerful, and in many cases smaller in size, managing the thermal profile has become an ever-increasing challenge. Monitoring the current provides a leading indicator to potential thermal issues.