18.02.2016

Dcdc converter 3.3v to 5v

For a project, I need to bring down power from a power source which may be in the range of 12v-24v down to 5v (for those who want to know, it involves a solenoid lock, which has a power input range of 12-24v, and a JeeNode to control it). A regular regulator would produce enormous amounts of heat, so that doesn’t seem like a wise choice :-). They do need a few extra components (coil and a few capacitors if I’m correct), but other than that, it seems like you can use those to replace a normal regulator, but with far less heat produced. Switching step-down regulators operate very similarly to Arduino’s analogWrite: they output a PWM signal with a pulsewidth that determines the average “on” time of the LED that is connected to the pin. Of course, this switching occurs at a high frequency: in the case of the LED, fast enough so your eye doesn’t see the LED blinking. The first model that you purchased seems to have just a simple PVC case and probably no screening metalwork inside.
If you want a glimpse into what noise pickup is possible, perhaps try out dzach’s excellent nRfMon spectrum visualiser. Technical term ;) for various toroids of extra lossy ferrite, strung along the cable and shrunk-wrapped. I’m a bit confused on how to select the “proper” one… I know that I should use one rated at least twice the Amps I need in my circuit, but are there other factors that I should be aware of? The bead is enhancing the self inductance of the wire passing through, so from the dimensions you can imagine the resulting uH are still pretty small.
The neat trick here is that the ferrite material is shared between the “out’ and ’return” paths. I will be using the 5v circuit (which gets lowered to 3.3v first by the JeeNode regulator) to control a transistor or mosfet, in order to switch the 12v to another device (the solenoid lock).
Seriously, what you describe is fine, but what they don’t tell you about the clamping diode, is that it is often too effective. If in your breadboard circuit, the solenoid seems “sticky” when de-energising, use the second of the circuits shown.
Without the zener, the return spike could be a relatively high voltage, which could spike back to the solonoid, and keep it “open”. Now, when you switch off a MOSFET controlling a coil, you will suddenly break the current path. Of course, if the current through your solenoid was big (1A), then that will be the current flowing through the diodes initially. Of course; I was just referring to the fact that I have no idea whether 3W or 1W is appropriate. Great graphic and yes, I’m guilty of relying on experience rather than running the numbers for the actual solenoid in use. For sizing the components, the analysis is best done in terms of energy - leave out the ‘power’ aspect until the end. The steady state energy stored in the coil is estimated from the steady state current flow (easy) and the winding effective inductance (harder - it changes with the position of the solenoid plunger).
Then an estimate of the time for the collapse event is needed - you can solve the damped RLC equation or take the short cut that its all over in say 1 second.
Then energy per the arbitrary one second event becomes power - size the diode(s) to this then check the peak device current is within bounds. This approach is conservative - which maps to long device life but maybe a little over in spec. Often, you put all that work in and find your original numbers were only overrating by 50-100% at room temperature. The actual failure mechanism in this case is that the current blip generates enough localised heat in the fuse link (under tension) gets hot enough to soften and “neck”, creating a tiny spot where the link crosssection is now smaller. Random electronic project: TDA2030A Amplifier for MP4 MP3 Player suggest reading the article.


An electric car still uses a 12 volt system to power all of the original 12 volt accessories: lights, horn, etc.
Our wide selection of dc voltage regulator (dc-dc converters, dc voltage reducer, voltage booster, step down converter, step up converter) also help you convert golf cart batteries (and other battery banks) to another voltage.
There are 3 USB converter circuits CP2102 USB communication as in the isolation section of the ISO7221 standard is being used.
So I started looking around, and stumbled upon “switching regulators” (like the LM2576 for example).
There are phone chargers (they also use switching regulators) that generate a lot of noise, spikes, and drift greatly, but if all you’re doing is charging a battery that’s no big deal. You could add some more capacitors to the output to decouple even further, but I hardly think that’s necessary, especially if you feed that 5V into the JeeNode’s own regulator. It is advisable to physically mount it well away from the JeeNode and possibly use a technique to stop that long wire acting as an aerial for the RFI junk it will generate. Is it for the RFM12B (which, in this case, I will not be using), or is for another (additional?) reason? I do order stuff from normal shops as well, but for small quantities, Ebay is great (well, except for the long delivery time of course :)).
I won’t be needing the RF12b in this case, but I think I might add it just to experiment with this phenomenon. If you look carefully at the sense of the windings, the fluxes generated by the load current passing are in opposite senses, so roughly cancel (differential mode). Apart from the required capacitors and reversed diode because of the solenoid, should I worry here about the noise as well? When the diode turns on (with the current “off” kick) it can act as a “slug” by circulating the stored energy around the winding R until is dissipates, the delay in collapsing the built up flux also delays the return of the solenoid to the resting state. The zener is there to lower the voltage to a voltage that is well below the switching voltage of the solonoid, so that it doesn’t “stick”. For large values of L, the current will diminish only slowly and the solenoid will seem to turn off very slowly: it will take a while for the current to reach 0.
A reasonable method is create a constant drive current and look at the quasilinear ramp time of back emf on the scope. This is not recommended, because it will cause the pack to discharge unevenly, affecting performance and battery life. This taps the full battery pack voltage and cuts it down to a regulated output, similar to that from an alternator.
Therefore, the coil and output capacitor form a low-pass filter to convert the pwm pulsetrain to a real analog voltage.
If you’re monitoring small signals or doing audio stuff, then of course the noise will greatly bother you.
It is easy to make by having an extra winding, well insulated from the other(s), on the storage inductor. Re-cycling an old laptop power adaptor cable with “lumps” works well, position “lump” as close as possible to the converter.
It is insidious stuff, leaks in everywhere, so can for example mess up ADC readings if you have sensors attached. So shunting the input side of the choke to ground with a small (both size and value) capacitor enhances the filtering a lot. Do the bead treatment symmetrically in the GND path or use a common mode choke before all that hash is injected into the logic ground.
This keeps the toroid out of saturation even for substantial load currents (a saturating inductor transitions from looking like an L into a lousy R). This effect is actually used to make DC delay relays which use a single fat closed loop of copper around all or part of the core - a slug.


This will last for only a short time, though, so you might not need a 3W zener; or maybe your current is lower. Sure - if the duty cycle is 1%, then the device has a long time to shed to heat from one event before the next. It is basically a reduction changer with the possibility of setting output voltage for a permanent stream in 3A. It also violates the isolation of the traction pack from the chassis, which is required by some components, and necessary for safety. Individual beads can’t use this cancellation method, so will be driven into saturation at a much lower load current.
Then the switcher MOSFET body diode will be sufficient to protect that device with its own minor shunting loop. If you add a protection diode, the coil current can no longer go through the MOSFET if you switch that off, but will instead continue to flow through the diode. The start event fits the Isquared x t curves and the duty cycle is low, so the fuse has plenty of time to recover between events. When buying circuit, it is necessary to buy circuit with Similarly, marked the perimeter without Adj is firmly set on production output voltage 5th without the possibility of regulation. One option in the early days of EVs was to use a deep cycle 12 volt battery, as heavy duty as possible, and recharge it when you charge the main battery pack.
Pulsing devices hard brings its own set of problems - if it is not on the spec sheet, it hasn’t been tested (or the results are so bad they are left out on purpose).
The problem here is that at very high pulse currents, it is still on the chart, but as non-repetitive, meaning once in a lifetime only. For example, with a simple mains cartridge fuse rated at 13A (very familiar to a UK audience) you can draw 50-100A for a short blip (a fuse blows based ~ on Current x Current x time) Great for starting up say a portable aircon unit where start current can be 5-10 x running current. As the battery drains in use, the headlights will grow dimmer and the turn signals flash more slowly. It can also effect the running of the car if some of the drive system components do not get the 12 volt signal they require.
This also eliminates the need for a separate 12 volt charging circuit for an auxiliary battery.
Bizim semam?zda R10 ve R11 olarak gorunen direnclerle saglanan gerilim bolucudeki gerilimle entegre icinde uretilen 1,23V’luk gerilimi kars?last?r?p c?k?s?n?n ac?k-kapal? surelerini ayarlayarak sabit gerilimli c?k?s verir. C3 uzerindeki gerilim Q1’in acma geriliminin alt?na dustugunde Q1 t?kan?r ve kontrol bacag? R9 uzerinden + hatta baglan?p regulatoru durdurur. Ancak, dar yere s?gd?rma gereksinimi nedeniyle ben 1000uF’l?k bir kondansator ile yetindim. Giris kondansatorunu ise, 6V’a kadar inebilecegim giris gerilimi uzerinden daha yuksek ak?m cekmek zorunda kalacag?mdan 470uF olarak sectim.
Veri kag?tlar?ndaki ac?klamalarda bu kondansatorler dusuk ESR’li (elektro statik direnc) tiplerden olmal? deniyor.
Uzerine 1mm capl? bobin telinden 15mm uzunlugunda yapt?g?m sar?m cal?smas? icin yeterli oldu. Hakk?nda ki bilgileri ve diger yaz?lar?n? gormek icin bak?n?z; gevv Etiketler: dcdc donusturucu konvertor LM2576 BURAK YELER birsey soracam devre semas?ndaki 20mH lik bobin resimde gozukmuyo kullanmasak olurmu acep?? Tetas elektronik urunlerinde (taksimetre, takograf) guc unitelerinde bu malzeme kullan?lmaktad?r.



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