New answers tagged switch-mode-power-supply
3
votes
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Current sense resistor determination
The NCP1606 is a constant on-time PFC controller operating in borderline conduction mode or BCM. There is no voltage sensing as in its current-mode version like the old MC33262 for instance. Capacitor ...
- 21.1k
2
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Generating a 60 Hz square wave to control a thin-film polarizing film with decent efficiency
Is my approach bad in terms of efficiency.
Well, boosting 24V to 100V and supplying this 100V to a H-bridge to have ±100V across the load can be a way to go, but would be more meaningful if your ...
- 30.4k
0
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Why is my simulation not loading when V2 has no current?
I see a few things wrong with the simulation, the first is the gate is floating on AD6407, this will make it difficult for the solver to determine what the sim is because of the floating gate. Add in ...
- 78.1k
3
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SPICE Error in LM5117 Model in Microcap-12
According to the manual page 556, Microcap does not use temperature coefficients for capacitors like it does for resistors.
Removing "TC=0,0" will fix the problem
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3
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UC3845 Soft start circuitry
A transistor is better than a diode for longer soft-start duration.
Consider the values in @Verbal Kint's answer:
I(CMP) (sourcing) is 0.5mA min, 0.8 typical, with no maximum given (presumably ...
- 27.5k
6
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UC3845 Soft start circuitry
Most of the industrial designs I have seen with a soft-start implemented around the UC384x were made the following way:
At power up, the capacitor is discharged and pulls the CMP pin low, minimizing ...
- 21.1k
4
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UC3845 Soft start circuitry
Nevertheless, can a diode do the work?
In order to implement the soft start, comp needs to be forced low and allowed to rise gently. The output of the error amplifier can push/pull by as much as 0....
- 2,090
1
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Output Stage Double LC Filter of a buck converter
I think that if the gain and phase margin are good and you can achieve the required loop bandwidth you should be OK as far as the loop goes. However, be sure to test at different load conditions. If ...
- 23.6k
0
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Using VOUT to Power Up a DC-DC Switching Regulator
No, the zener diode is for a reference for the HB pin, Vcc in this part is an output not an input. Vin is the input.
- 78.1k
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Sampling gain effect in buck converter
Pulse width modulation used in the control of power supplies essentially causes a phase delay in the loop, similar to the sampling delay in a pure digital system. When the inernal ramp voltage reaches ...
- 132
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Sampling gain effect in buck converter
Let me try to give a simple answer to this question. Current-mode-controlled converters are made of two loops: an inner current loop and an outer loop which ensures voltage regulation. The error or ...
- 21.1k
-1
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Why is a capacitor connected across the power MOSFET in the DC-DC stage of most SMPSs?
The capacitor catches and changes the harmful Instantaneous Fleeting voltage by slowing it down in a controlled manner, also bringing it more closer in phase with the slower amps released from the ...
- 1
0
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How damaging are inrush currents?
Inrush current from power supplies mostly for led lighting have short duration but high amp.They destroy circuit breaker contacts,switches,timer contacts,contactor contacts and Eazy can trigger C type ...
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4
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SIMPLIS - Buck CM from C. Basso Website
The circuits I provide in my 90+ ready-made templates are simplified versions of what a real controller would do. It is for clarity reasons, so that everyone can understand the operating flow, but ...
- 21.1k
1
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How to decide number of layers?
Most designs need only four layers if you need more for current carrying capacity then increase the thickness and get more than one ounce copper weight when you order the PCB.
Typically only high ...
- 78.1k
3
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How to decide number of layers?
More layers = more cost, in general.
1 layer: only for the limited cases of mass production where saving
cents per unit counts, or for home-etched PCBs. Often have to use
link wires to join up parts ...
- 406
4
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Output stage filter of a buck regulator and ESR
It makes me confused about what is really ESR. Whatever is ESR, it seems that It is varying according to the frequencies.
KEMET uses SPICE models to plot ESR and Impedance (Z) graphs. Following is ...
- 30.4k
2
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Output stage filter of a buck regulator and ESR
If you know either the self resonant frequency or ESR@120 Hz and ESL, I would model it as an ideal capacitor with series L and C. If the impedance plot is a nice V from the manufacturer or your own ...
- 13.8k
0
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BD8306MUV and idle current
Is this normal, or do I have an error somewhere?
Looks normal to me.
Apparently, you copied the first application circuit given on the p.11 of the datasheet. There are some performance graphs on p.13 ...
- 30.4k
1
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How is voltage regulated on the output of this supply?
Voltage too high -> TL431 draws more current through opto
Voltage too low -> TL431 draws less current through opto.
The other half of the circuit uses that signal to regulate the output. This ...
- 779
5
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Direction of current flow in SMPS flyback converter doesn't make sense
The flyback "transformer" is actually a coupled inductor and not a conventional transformer.
During the "on" time energy is stored in the magnetic field and current ramps in the ...
- 23.6k
2
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What is the difference between voltage mode control and current mode control for SMPS?
The difference is in how the control loops are configured. An oversimplified picture follows:
In voltage-mode control, the voltage is sensed and compared to a reference, and this difference is applied ...
- 30.4k
4
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Which is the more important switching parameter in MOSFET datasheet? Turn on/off/delay times or Input/Output/Reverse capacitances?
Timing tells you how long it will take for it to switch. So this sets the speed you can operate them, setting maximum frequencies which you can use.
Capacitance tells you how much energy you need to ...
- 4,096
4
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Is it a good idea to place SMPS output capacitor close to inductor?
It looks like you have a high voltage buck converter here. This layout looks good by eye to me, as long as you have a solid ground connection.
If you're soldering these by hand and the capacitor isn'...
- 170
2
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How can I separate the switched-mode power supply from the RF PCB to avoid interference?
That sounds like a broad question but I'll try my best to give some general info whilst keeping the answer not too long.
The presence of a switching regulator is enough to get both conducted and ...
- 30.4k
1
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Circuit to convert 14.8v battery with max 4a discharge current into 12v, 9v and 5v output?
To reduce unwanted interactions (e.g., motor noise vs. control circuits), it's an advantage to have three separate power supplies.
One might derive a 5 V supply from the 12 V rail with resistors and ...
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3
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Identifying SMPS transformer
The inductance and resistance of a transformer can be measured with simple tools, for example a signal generator (sine preferred) and oscilloscope. At least an AC voltmeter, or preferably vector ...
- 27.5k
11
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Accepted
Why should I route the feedback trace under the output capacitor?
I doubt it matters.
Appnotes love to go overboard with layout instructions, but without explaining what and why; let alone giving quantitative values, or comparing alternative layouts with ...
- 27.5k
21
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Why should I route the feedback trace under the output capacitor?
The reason for this is that there's a very large ripple current flowing from the output inductor down into the output filter capacitor. The trace between these two isn't perfect (it has resistance and ...
- 15.6k
0
votes
Driving MOSFET with the PWM output of TL494
You can use discrete gate driver that consists from two transistors. I simulated it in LTSpice. The turn-of time (with given resistors) is roughly 300 nano Seconds. Turn-on time is roughly 100 nSec. ...
1
vote
Accepted
Voltage spikes on switch-mode power supply Vout when disconnecting barrel jack
Excellent waveforms. You have... if not the smoking gun, then at least some "warning shots" fired from it, say?
The MCU board appears to be using a ME6211C33 regulator, with 6.5V absolute ...
- 27.5k
3
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Simple forward converter - strange demagnetisation
I think it's D1 reverse recovery.
It definitely looks weird in the first waveform. It seems clearer in the second. I'm not sure what exactly is going on, but it seems likely it has to do with the ...
- 27.5k
0
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Voltage spikes on switch-mode power supply Vout when disconnecting barrel jack
Following on from a comment by Justme on another answer, the problem may be that the contacts on the barrel jack are bouncing. The regulator is then struggling to regulate the voltage when its load ...
- 19k
2
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Voltage spikes on switch-mode power supply Vout when disconnecting barrel jack
The Traco TSR 1E Application Notes available at https://www.tracopower.com/int/series/tsr-1e contains the following with a suggested EMI filter:
While you may not need the full filter if you don't ...
- 1,504
0
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Voltage spikes on switch-mode power supply Vout when disconnecting barrel jack
The switching regulator may need no extra protection, but the pulse may still pass downstream.
This kind of “spike” is common when using wallwarts.
A TVS with a must-work voltage greater than the ...
- 13.6k
1
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Can someone please explain this circuit? SMPS, Bridge Rectifier, Transformer
It's some form of magnetic flux tuned shunt, it positively reacts to reverse transformer flux producing a shunting to the bridge gnd. the function of the other 2 shunt resistors may be to provide ...
- 11
8
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Accepted
Can someone please explain this circuit? SMPS, Bridge Rectifier, Transformer
It looks like it is a ‘soft start’ circuit. At startup, C010 charges gently via the bridge rectifier and R001/R060. Once charged, the power supply circuit starts up and the extra transformer winding ...
- 6,090
1
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What transformer should I use for high power switching?
To be safe you better galvanicly isolate your MOSFET from your Arduino with perhaps a small transformer of fast optocoupler. Do this to avoid electrocution. Now you can think about not blowing up the ...
- 14.3k
1
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EMI filter attenuation requirement for a buck converter given EMI compliant AC-DC converter
It's a peculiar thought, to consider a power supply as a two-port:
simulate this circuit – Schematic created using CircuitLab
A power supply is generally a very nonlinear system, particularly ...
- 27.5k
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