Power Supplies

Adjustable Current or Voltage Source DC-DC Reference Design

MagI³C Power Modules from Würth Elektronik are dc-dc converters with integrated controller IC, inductors, and capacitors. Using the MagI³C Power Supply Reference Design, the manufacturer demonstrated the ease of building an adjustable current or voltage source with a MagI³C Power Module. The board is based on the MagI³C VDRM (Variable Step Down Regulator Module) with two control loops added.

The design targets various applications that require an adjustable power source. The reference design generates a constant voltage with an adjustable maximum current, or it can be set to generate a constant current with an adjustable maximum voltage.

In the two operating modes, the output voltage can be set from 0V to 15V and the current from 0A to 2.5A. The input voltage range is 7V to 36V. LEDs on the board indicate the voltage regulation mode, current regulation mode, and a missing output voltage.

The output voltage and output current are conveniently set on two potentiometers.

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An adjustable output current limit can be set from 0mA to the module’s maximum continuous output current, transforming the module into a constant current source or serving as a voltage source but with a user-defined current limit.

Functional diagram (Click on image to enlarge)

An electronic fuse can be implemented by triggering on the current limit LED and pulling the enable pin low to shut down the MagI3C Power Module instantly after a current limit event.

Output voltage and current can have arbitrary waveforms. For example, they can imitate the behavior of a car battery voltage during engine startup to test if the radio is malfunctioning.

The reference design board can charge batteries with dc. It can also charge batteries with a defined charging current waveform, if PWM output of a microcontroller or a digital to analog converter is used instead of the potentiometer for current adjustment. Other potential uses include end of charge voltage as well as supercapacitor charging. High-power LEDs can be supplied up to 2.5A.

The point of regulation can be moved towards the load and away from the MagI3C Power Module, allowing regulation of the Voltage at a distant point while the module’s output voltage adapts to the voltage drops of the supply lines.

During the development of a prototype, the MagI3C Power Supply can be implemented into the prototype housing until the power supply is defined for the final product.

The reference design can be used to drive white, infrared and ultraviolet power LEDs or can be employed as a battery charger for lead, NiCd, NiMH or lithium-ion batteries. It can also be used as supercapacitor charger and a mini-lab power supply.

Electrical Specifications
  • Input Voltage Range: 7V to 36V
  • Input Voltage Transients: Max. 45V
  • Output Voltage Range: 0V to 15V
  • Output Current Limit: 0A to 2.5A
  • Maximum Output Power: 37.5W
  • Switching Frequency: 1MHz
Features
  • Output On/Off: Mechanical Switch
  • Constant Voltage Indicator LED: green
  • Constant Current Indicator LED: red
  • Output Fail Indicator LED: red

Available immediately for order under article number 178002. The documentation DNS002 for the reference design and the CAD data are available online in the product catalog.

Würth Elektronik
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