step-down switcher for the 5V supply?

Home › Forums › TinyG › TinyG Feature Requests › step-down switcher for the 5V supply?

Viewing 3 posts - 1 through 3 (of 3 total)
  • Author
    Posts
  • September 30, 2012 at 12:44 pm #3542
    s.carlier
    Member

    I received a TinyG v7 last week — I expected a v6, I was pleasantly suprised! Both the hardware and firmware work extremely well, it is a great piece of work!

    I am a little worried by the MC7805C 5V linear regulator, which gets hot when powered at 24V. I realize it is a rugged part, and it looks like it should be able to supply up to 130mA before entering thermal shutdown, passively cooled at 24V IN. The board seems to draw about 70mA idle, the 4 red LEDs about 30mA together. The RS485 driver however can source/sink a lot of current…

    For my own peace of mind I replaced the linear regulator on my TinyG with a tiny homemade switching supply I had lying around (an LM2674 IC, a 47uH 6x6mm inductor, a 0.5A SOD-123 schottky diode, and a few capacitors). It works well and it would quite easily fit on the PCB, though it might add about $5 to the cost of the board.

    Has such a change been considered for future revisions?

    October 1, 2012 at 7:39 am #3543
    ril3y
    Keymaster

    short answer is yes we are planning on doing pretty much the same thing that you did however we haven’t had any problems with it overheating sofar. are you using the  RS 485I or planning to the future?

    October 1, 2012 at 8:07 am #3544
    s.carlier
    Member

    Sounds good! Have you also considered adding a (0.5A?) polyfuse on the 5V supply, and a 2-pin connector to allow powering add-on boards from it? I would love to see these on future revisions.

    I plan to use RS485 to interface with a spindle speed controller (serial communication is more convenient than PWM for my design) and perhaps optical encoders to experiment with closed-loop control.

  • Author
    Posts
Viewing 3 posts - 1 through 3 (of 3 total)
  • You must be logged in to reply to this topic.