How potential/voltage dividers compare to voltage regulators?

Other Hardware General Electronics
13

Bobu:
Just realised the datasheet shows a typical set up for setting up a switcher regulator :S

I did have some questions though about why you set it up this way (sorry for going off the original topic slightly). Could someone confirm my understanding of why it's set up this way and answer some questions on it (again sorry for having to ask questions that I assume are basics, but my background is on the software side so I'm pretty much a beginner when it comes to hardware):-

  • Pin 1 is the input voltage. The capcitor that's 100?F, is to help smooth the input voltage
  • Pin 2 is the output. It's connected to an inductor that stores the output charge? The capacitor that follows (1000?F) is to smooth out the output voltage? I'm not sure what the last symbol represents (solid black triangle pointing upwards with a sine wave line over the top)?
  • Pin 3 is ground
  • Pin 4 monitors the current amount 'charged' so it knows whether is should activate or deactivate pin 5
  • Pin 5 controls whether it needs to charge or shut off the voltage depending on the state of whether it has charged 5v

Cheers

The inductor stores energy as magnetic field (the energy is associated with current flowing). Capacitors store energy associated with a voltage. Pin 5 is the on/off control for whole regulator. Pin 4 senses output voltage. Pin 2 is the switched output (there's a MOSFET or transistor on the chip switching the current from the input at a high frquency).

When the switch is on current flows from input (thus from Cin) to the output (Cout), when the switch is off the current still flows (that's the inductor's job) but has to go through the schottky diode D1 instead.

When the switch is on the voltage across the inductor causes the current to rise, when the switch is off the reverse voltage across the inductor causes the current to fall (but not reverse). If you switch fast enough the current through the inductor is mainly DC (with ripple) but sometimes the current comes "magically" from ground via the diode rather than from Cin.

This is because of the stored energy in the inductor being released as the current falls.