ATtiny13a Flashlight Driver Question

Discussion in 'Embedded Systems and Microcontrollers' started by denos, Apr 21, 2011.

  1. denos

    Thread Starter New Member

    Sep 14, 2010
    3
    0
    I see this design pattern repeatedly in AtTiny13a based LED flashlight drivers:

    [​IMG]
    Similar:
    [​IMG]

    I'm having a hard time making sense of the red line (Vcc) trace. Pin 6 on the ATtiny13a is driving 3 x AMC7135 current regulators in parallel (or at least that is how it appears to me). Each of those current regulators generates a constant 350ma of output for a total of 1050ma. Aside: pin 6 is manipulated with PWM to provide multiple brightness levels. The ATtiny13a is restricted to 40ma per I/O pin so it can't possibly be sourcing > 1A to the 3 regulators. What have I misunderstood?

    Links:
    ATtiny13A Datasheet
    AMC7135 Datasheet

    Thanks!
     
    Last edited: Apr 21, 2011
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    The 350mA current flows into the Output of the current regulator (AMC7153) and not into the Vdd pin. The microcontroller controls the Vdd pin of the current regulator which is only used to power the internal circuitry of the current regulator. This current into Vdd pin might be in the range of uA.
     
  3. jt6245

    Member

    Feb 18, 2011
    21
    3
    datasheet shows typical vdd pin current is 200uA (Idd).
    output pin is open drain circuit.
     
    Last edited: Apr 22, 2011
  4. processed in everything

    New Member

    Jun 27, 2011
    1
    0
    What about the circuit of Xeccon flashlights, are they similar to these flashlights?
     
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