switching frequency of LM can be adjusted to any value between kHz and .. mode. All the analysis in this datasheet assumes operation in continuous . Part Number: LM, Maunfacturer: National Semiconductor, Part Family: LM, File type: PDF, Document: Datasheet – semiconductor. Datasheets, LM Design Resources, LM Design with WEBENCH® Power Designer. Featured Product, Create your power design now with TI’s.

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Min and max output voltage are VDC, output current is 0.

LM from Texas Instruments

Current sense resistors One of these is the resistor that goes datasheft the switch and ground. Here’s the one for the boost converter: Output capacitor selection You want something big with low ESR. One of these is the resistor that goes between the switch lm34478 ground. So with a maximum input voltage of 12V, and an output current of 0. We need to find Q, which is the damping factor.

We can see that unity gain occurs at 2. Next, compute the duty cycle, D. Doing so without going through the math shows that datasyeet is not possible to pick a reasonable sense resistor while still maintaining a good current limit. And, a Schottky diode is recommended for high speed.


Well actually there is no conclusion until I actually get the parts in to build this thing.

We first calculate the datasjeet sense resistor for current mode loop stability loop stability is always a good thing:. You can see the resonance at half the switching frequency. Duty cycle Next, compute the duty cycle, D.

The problem is, without knowing control theory, it will be difficult to select the compensation components. Design a boost converter that gives VDC at 0. Clearly such a switch has to shut off well before 78ns.

Again, this is from the Adafruit calculator, but here is the daatasheet. So, let’s take a look at the application note to see what the transfer function looks like without this compensation.

About Us Contact Hackaday. I think I will have to look at other chips such as the LT The converter is a feedback loop, and such feedback loops need to be stable, otherwise your power supply might fail at certain frequencies. And so I get a current of 4. Maybe start datasheef this list of videos?

A boost converter design

Here we see the gain lk3478 is 3. This means that in gain it acts like a zero, but in phase it acts like a pole.


I don’t know, but suspect that the output voltage of the adapter will drop under load, so I’m just going to go ahead and specify a minimum input voltage of 8VDC. The diode has to be able to carry the maximum datsaheet current. So, in fact, this converter with the components so far needs no compensation network, and we can leave the COMP pin unconnected.

Anyway, this is a good worked example, and very relevant! Also a duty cycle switch on-time to total time of 0.

A boost converter design | Details |

I chose kHz because I wanted it to be above the minimum, but not so fast that all my components had to be super-fast. If Q were infinite, the thing would vibrate itself to pieces and catch fire at half the switching frequency.

Switching frequency First, choose a switching frequency between kHz and 1MHz. Thus, instead of a maximum sense resistance of 0.