ATtiny13a Flashlight Driver Question

Thread Starter

denos

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


Similar:


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:

mik3

Joined Feb 4, 2008
4,843
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.
 
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