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Active clamp flyback control questions

The active-clamp flyback (ACF) has gained popularity with the high-density USB 3.0 chargers. Owing to its zero-voltage switching (ZVS) on the main power transistor, the designer can push the switching ...
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Active clamp flyback control questions

About Active clamp flyback control, can I use SR flip to control it? Sure you can but, will it make any improvement, no. Look at the body diode symbol in the MOSFET; it will naturally conduct when ...
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SMPS electrical noise issue

It is unlikely that the SMPS is what is causing your issues. This is even what you're observing: the touch screen works fine if the SMPS is powering it as long as there is a protective earth ground ...
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2 votes

Sanity check ±12 V/+5 V PSU PCB

You may be able to get by with two layers, four layers is probably not needed with the cross sectional area of copper with the current levels (~3 amps) that you have. Other than that you might want to ...
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What does V xtor (max) mean in this equation?

Vxtor appears to stand for voltage across the switching transistor. See above for "MOSFET DC Losses". Fig. 2 also supports this interpretation with Q1/Q2 and Rs in series with the primary ...
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Isolating the solenoid and driving relay power supply

Some relay modules have optocouplers to isolate the microcontroller side from the relay side and have a jumper to optionally tie the power supplies. My (possibly incomplete and/or incorrect) ...
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Need help understanding error amplifier compensation

Before attempting to compensate a converter, you need to extract the control-to-output transfer function (TF) of the power stage: if a sinusoidal stimulus is applied to the control input of the said ...
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1 vote

How to control high current voltage with small current voltage linearly?

Here is a simple circuit that might give you some ideas. It's very inefficient (4W dissipation during charging, as you can see in the top trace). U1 controls the charging current at 500mA based on ...
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What is the "Smart Battery Connector" for 9V rechargeable batteries?

Since you don't have a smart battery, you can e.g. use the variant MAX1648, where you configure the chemistry, voltage and current by hardware. The smart battery interface can be considered as a kind ...
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Op-amp non-linear Bode plot

I would like to know why the real OPA will have these two poles If it didn't have FP1 it would have infinite gain at pure DC and that ain't happening in the real world we live in. Also, look at the x-...
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I built a DIY DC-DC buck regulator. It's getting extremely hot. Why?

Where is your input rail decoupling cap .This is important .Put one in like say 10microfarad ceramic as a minimum.Without the cap your chip is breaking inductive current which means energy .This ...
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3 votes

Op-amp non-linear Bode plot

Any amplifier will have gain that drops off with frequency, and accompanying phase lag. The plot you're showing is typical of an internally-compensated operational amplifier that is designed to be ...
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1 vote

Minimum load current on boost converter

p. 15 of the data sheet mentions 'discontinuous conduction' mode. When the converter switches to this mode, portions of switching cycles are skipped (the exact method isn't clear), but the converter ...
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3 votes

Over-power protection circuit

The method you propose could be an option but it is complicated to implement in an integrated circuit. You would need to sense the input current and voltage then do a multiplication and compare it ...
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11 votes

I built a DIY DC-DC buck regulator. It's getting extremely hot. Why?

The 10 μH inductor is unsuitably low in inductance. Since you know output current, output voltage, input voltage, and switching frequency, you can plug the values into the formula given in the ...
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Efficiency when splitting output from switching AC-DC power supply

Since the power draw of your always-on devices is something you can’t change, all you can do is use the most efficient supply available, which would be a switching power supply. If some or all of the ...
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Efficiency when splitting output from switching AC-DC power supply

Let‘s have a look at how a switching PSU works. In its simplest description, it has a switch and some kind of energy converting element (usually an inductor). The switch controls how much energy is ...
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Efficiency when splitting output from switching AC-DC power supply

The power supply will "waste" power at (1-efficiency) * Pout. Some manufacturers will give you a maximum and/or minimum efficiency, while others will give you a curve. See: https://www.cui....
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2 votes

Adjusting output voltage feedback with a Howland Current Pump

This worked for me: simulate this circuit – Schematic created using CircuitLab For DAC output 0 V you have the original divider For DAC output 2.4 V TO_FB is close to 1.2 V, output voltage is ...
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Boost output impedance simulation

This is the way I performed the \$Z_{out}\$ ac sweep for the analysis in my last book on transfer functions. Please note how the circuit is drawn, with clear connections and well-arranged components. ...
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Triangle RMS calculate

Maybe this proof will help (it's an AC triangular voltage waveform that is initially calculated but, the same principle applies to a triangular shaped current): - But, when the waveform is biased ...
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10 votes

Why can't flyback work when the duty cycle is greater than 0.5?

Unlike the forward converter, there is no theoretical limit for the duty ratio of the flyback converter. This is discussed in this thread and intuitively, you understand that too large a duty ratio ...
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4 votes

Why can't flyback work when the duty cycle is greater than 0.5?

The simplest explanation may just be the volt-second balance. If you apply a pulse of Vin for time Ton to charge the magnetic field with input current, it takes the same amount of volt-seconds to ...
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1 vote

Flyback Frequency Foldback Mode (FFM) and Skip Mode

Frequency foldback is a method used to improve the efficiency of a converter when the load current is decreasing. When looking at losses in switching semiconductors, some part depends on frequency ...
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Flyback Frequency Foldback Mode (FFM) and Skip Mode

Working on little context. To prevent short circuit or overload conditions. Frequency foldback as shown above is simply reducing the switching frequency. Its main purpose is to reduces operating ...
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ZCD SIMPLIS function block questions

This (U7) is a monostable flip flop, sometimes called a 'one shot'. It is typically used to produce a single pulse each time it is triggered. You can be use it to debounce a mechanical switch so that ...
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Peak current mode control question

The 2nd is correct. In peak current mode, when the inductor current reaches the level set by the controller, the latch is reset and the highs-side switch turns off. With the logic shown, high current ...
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2 votes

Choosing output capacitor for Power converting Switching regulator (Cout_Eff)

There are no three separate ways, the capacitance must be chosen in a way that is suitable with all the equations. If you don't use the VFM mode then you don't have to make sure the capacitor fits ...
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Driving a BLDC motor with mosfets (highside driving)

The body diodes of the MOSFETs are still there if you turn them off! So the current of an activated battery will flow back into all other deactivated batteries. 16 pF as timing capacitor for NE555 is ...
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