A Precision, High Intensity and Programmable Current Power Supply for LED in Biomedical Applications

In Biomedical photonics, a precision current source with high intensity and programmable, which can generate pulses of variable frequencies, is necessary to drive devices such as LED or LED lasers. Such a source was built, and different applications in the biomedical field have been explored. The circuit consists of a power section providing sufficient power to the MOSFET for the generation of a current source of up to 15,000 mA, and the control section using an Op-Amp circuit with no feedback that controls the current level passing through the MOSFET and generates a pulse trigger for frequency control. Managing the input voltage of the Op-Amp circuit, a 16-bit DAC of the ARM Cortex-M3 was used. The current source was tested with a FLUKE current meter, and pulse duration was calibrated with a Tektronix Oscilloscope. The source can provide a continuous current of 0 mA – 2,000 mA with an accuracy of ±1 mA, and a continuous pulse current of 0 mA – 15,000 mA with an accuracy of ±4 mA. It can supply up to 30 V with a continuous current power of 60W and a pulse source power of 450 W. Moreover, the source can also generate current pulses with a duration from 10 µs with an error of ±0.5 µs to 200 ms with an error of ±0.5 ms. Single pulses and multiple pulses of variable frequencies can be generated as well. In inclusion, the source was used to drive LEDs successfully for imaging applications. Other applications in biomedical photonics have been sought.