Lab bench power supplies are the most essential test and measurement equipment used in laboratories.
Lab bench power supplies can be either single-channel or multi-channel, bipolar or unipolar, or linear or switching.
The de-facto features to look for while selecting a lab bench power supply are voltage range, current range, and power envelope.
The best lab bench power supplies offer high accuracy, reliability, multiple channels, constant voltage or current adjustments, short-circuit protection, and overload protection
Lab bench power supplies are invaluable tools required for testing circuits in scientific or technical laboratories, educational institutions, and research and development facilities. A reliable and versatile regulated DC power supply is often utilized for the lab bench power supply, which powers the circuit so the engineer can test for set voltages. A lab bench power supply typically provides voltage and current adjustments to cater to specific testing requirements, and there are several features needed in lab bench power supplies. The best lab bench power supply offers high accuracy, reliability, multiple channels, constant voltage or current adjustments, short-circuit protection, and overload protection.
DC Power Supplies and Circuit Testing in Laboratories
A reliable, regulated DC power supply is a staple requirement of any electronics laboratory. The DC power supply powers the device under test, such as a breadboard circuit, a printed circuit board, or an electronic product. For testing, a voltage or current is set in the DC power supply and is connected to the device under test. The engineer expects a certain output for the set values of voltage or current. If the actual output matches with the theoretical output determined by the engineer, then he or she can confirm that the device under test is operating as planned or designed. In case of any deviation from the expected output, the device under test goes in for troubleshooting and further testing.
In most testing experiments to verify the circuit under different conditions, the DC power supply is swept over a range and the output is examined. To perform the DC sweep in hardware circuits, a variable DC power supply is required. The user sets the voltage or current to different values each time and the corresponding output is noted. To conduct such experiments, the DC power supply present in the lab should be an adjustable or variable source. In certain tests, the supply needs to be a constant voltage source or a constant current source to meet the circuit requirements.
Similar to the constant voltage or constant current programmable modes, several features are required in a DC power supply to test circuits. Most required features are the same, other than the voltage or current range. These common features allow engineers to depend on the same DC power supply to test different circuits. A reliable source of DC power in the lab, termed “lab bench power supply,” furnishes the circuit testing requirements.
Lab Bench DC Power Supplies
To supply DC power to test circuits or prototypes in laboratories, lab bench power supplies are used. Any circuit that can produce an adjustable DC voltage as output when plugged into the AC mains is the most common type of lab bench DC power supply in use. Lab bench power supplies are the most essential test and measurement equipment used in laboratories. They can be categorized as:
Single-channel or multi-channel - Single-channel lab bench power supplies provide one DC output, whereas there are multiple DC outputs in a multi-channel power supply.
Bipolar or unipolar - The DC voltage can be positive or negative. If a lab bench power supply gives both positive and negative DC voltage, then it is called bipolar supply. When the DC voltage is positive, such lab bench power supplies are unipolar.
Linear or switching - The pass element in a lab bench power supply circuit can be utilized as a linear device (active region) or switching device (saturation and cut-off region). The operating region of the pass element defines the lab bench power supply as either linear or switching.
Lab bench power supplies can be off-the-shelf products or custom-designed circuits. The off-the-shelf lab bench power supplies are often designed with knobs to adjust the voltage to the required value. The voltage can be adjusted using coarse and fine adjustments to set the value correctly even up to decimal places. The current limiting feature is usually incorporated in commercially available lab bench power supplies so that the engineer can set the current value just above what the device under test draws. By setting the current limit, the damages caused by shorts and overcurrents can be prevented. Like current limiting, there are a few other features needed in a lab bench power supply.
What Are the Features That Make the Best Lab Bench Power Supply?
The key features to look for when selecting the best lab bench power supply are its voltage range, current range, and power envelope. Another important feature that protects the lab bench power supplies from shorts is current limiting. Some other features to look for include:
Number of channels: For testing an electrical hardware setup requiring different DC voltages simultaneously, multi-channel lab bench power supplies are best.
Noise level: Sensitive circuits need to be supplied from a DC power supply of low noise levels. In such cases, linear lab bench power supplies are preferred over switching power supplies.
Response time: The response time is the time taken by the power supply to rise or fall to a set voltage. A low response time lab bench power supply is best.
Programmable modes: In lab bench power supplies, the constant voltage (CV) mode supplies a single voltage over a selected range of currents and the constant current (CC) mode offers a constant current over a range of voltages. The availability of CV or CC mode is essential in lab bench power supplies for testing purposes.
Under-voltage lockout (UVLO): The under-voltage lockout in a lab bench power supply cuts off the power when the supply voltage drops below a certain value.
If off-the-shelf lab bench power supplies are not matching the testing requirements, you can custom-design the DC supply. The best lab bench power supply for your circuit testing can be custom-made using Cadence products.
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