# Tag Info

## Hot answers tagged dc-dc-converter

5

Wider traces exhibit less resistance, but more significantly less inductance. The lower resistance and inductance helps a little bit with efficiency, and a little more with ripple, but the larger gains are in EMC. A lower inductance trace radiates less, particularly in conjunction with a solid ground plane.

4

I have a 12 V DC input that I am stepping down to 2 V with 610 ohm resistor. When power is removed the light is staying on for a period of time and slowly dims. I suspect that you mean when you switch off the mains power that the LED fades out. simulate this circuit – Schematic created using CircuitLab Figure 1. An old-fashioned power supply driving ...

4

I recommend picking a topology, and running down the design path enough to get a feel for if you can meet your requirements. If you can't, and can't see a way to easily fix it, move on to the next topology and repeat. If you run out of topologies, edit your question to reflect the work you've done, where you're having trouble meeting the requirement, and ...

3

Picking a topology for a DC-DC converter starts with defining the requirements. Personally, I'd first check the necessity of isolation. If it is not necessary then, depending on the relationship between VOUT and the range of VIN (e.g. check if output voltage will be lower than input voltage for the whole input range, as in your case) I'd go for buck (output ...

2

Trace at point A carries high di/dt current so it should have low inductance to the decoupling capacitor to minimize voltage spikes. $e = L \frac{di}{dt}$ and in dc-dc converters di/dt is pretty high so you want to minimize L. A few amps switched in a few ns with a few nH inductance = VIN drops a lot when it switches. I've had a case where this trace ...

2

What is your technical definition of a PWM controller? – Andy aka @Andyaka A circuit that changes the duty cycle of a constant frequency pulse wave outputs in response to analog inputs OK, just like an LTC6992 then. Does anyone knows if it is a useful practice to build a PWM controller from discrete components or not and why? I'd say it's not ...

1

The way I would think of this is that the 25uF capacitor and associated 1N4148 diode form an analog of the output voltage on the mains side of the transformer. I think there's something wrong with where the zener diode and/or 3.9K resistor goes- it should inhibit the base drive of the BJT to regulate the voltage. Edit:- The red LED effectively goes on ...

1

You can control the noise pickup by using the usual copper-foil of planes, to be magnetic shields. And the planes are of course fine electric-field shields, as long as you tie the E_field collection regions to the larger Ground system to prevent radical upsets of the pieces of metal by "displacement currents". I suggest you design your discrete analog sense/...

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