• PicŪ Basic


  • Active Current Limit

    A Nifty Circuit !

    This circuit offers active current limiting, without the associated complicity expected. Tried and tested, it works like a dream. The transistor begins to switch on when it's 0.55V threshold is exceeded, trimming the gate voltage down to where the voltage over the sensing resistor limits it.

    Applications could range from LED current limiting to active current control for dc or stepper motors.
    A higher supply voltage for stepper motors would gain extra speed without the risk of overcurrent.
    Note that the drive signal does not have to be PWM, it could be just a 0 ro 1 to the gate also.

    Remember if you switch the FET with DC, the FET will be in linear mode when current limiting occurs,
    so watch the wattage in the FET ! It is less of a problem in switched (PWM) applications.




    The original circuit was submitted by David from Auckland, New Zealand.
  • Recent Activity

    towlerg-21522

    Mysterious PORTB problem

    Thread Starter: xldaedalus

    I'm using Proton+ to develop firmware for a product with switches. The MCU is an 18F26K22. Most of the switches reside on PORTB. I am NOT using a...

    towlerg Today, 15:45 Go to last post
    tumbleweed-20435

    PIC18F1330 PLL problem

    Thread Starter: rcurl

    I'm just starting out on a new project that uses a PIC18F1330. I haven't used this specific chip before, so I began by trying to blink an LED just...

    tumbleweed Today, 18:02 Go to last post
    towlerg-21522

    Pic16f18877 oread

    Thread Starter: evoortman

    Hi, On a PIC16F18877 the OREAD command doesn't seem to work. The code is working on a PIC16F1939. Both controllers use 32MHz int osc. If i...

    towlerg Today, 15:59 Go to last post