A Guide on Programmable Power Supply

The programmability aspect comes with regard to these power supplies being digitally controlled. They are controlled to provide accurate, adjustable levels of voltage, frequency (only for AC power supply) and current. These three functions can be referred to as the controllable functions. 

Such power supplies provide remote control capabilities of the output power digitally. Output power characteristics can also be controlled via analog control signals controlled by the keypad from the front panel of the power supply. Alternatively, it can be done via a computer interface like USB.

Components of Programmable Power Supply

A typical programmable power supply has these components:

• A processor
• A current shunt
• Readback circuit for voltage

Some power supplies come with extra features like overcurrent and overvoltage protection. Comparators will measure the output voltage against a program reference value. 

Whenever the output value outweighs the reference value, a trigger signal is then sent to a silicon-controlled rectifier across the output. What this does is shutoff the source to the load.

Real World Applications

Semiconductor Fabrication

Semiconductors all come from silicon so naturally, the manufacturing of a single-cell crystal is the first step in making a semiconductor integrated circuit. Adjustable power sources are used to control specific processes as well as monitor the crystal growth process.

The adjustable power supplies facilitate power and feedback to take control of the crystal growth environment.

X-Ray Generators

These X-ray generators are simply used in industrial imaging applications like material composition and metal fatigue testing among other diagnostic equipment. These power supplies are critical because they provide control of electrical power limits needed to power the X-Ray tubes and allow real time monitoring and control of power limits for high level accuracy.

Automatic Test Equipment

Automatic test equipment (ATE) enables product testing with minimal human intervention. ATE is widely used in the aerospace production industry with planes, spacecraft, and satellites. Additionally, ATE is used in the production of semiconductors and hard drives. Power supplies of this nature are important for programming of hard limits to provide test and validation of products before installation.

Switching Power Supply

Any AC-DC power supply must convert the AC at the input into a regulated DC supply at its output. 

Programmable DC Power Supply

The basis of operation of this kind of power supply is to deliver stable and precise current and voltage. On top of that, the power supply should have minimal noise to any type of load with regard to resistance, impedance, and state. 

Direct power supply outputs come in two settings:

Constant Current

Also called safety mode, the output current is constant,as the name suggests. The current is constant and determined by the user’s current limit setting. Voltage, on the other hand, is determined by the impedance of the load. Impedance is the effective resistance of an electric circuit birthed of resistance and reactance. 

If the power supply is in current voltage mode and its current exceeds the user’s current limit setting, the power supply will then automatically revert back to constant current mode. The power supply can also revert back to current voltage mode if the load current falls below the current limit setting.

Constant Voltage

In this programmable DC power supply, the voltage is controlled. It is also worth mentioning that this mode is the typical operating state of a power supply. Obviously, the output voltage is constant and is determined by the user’s voltage setting. The output current is determined by impedance of the load.

When it comes to switching power supply, the most important parameter is max voltage, max current, and the max power that the power supply can generate. Ensure the power supply can deliver the power at the required voltage and current levels.