14
votes
How come negative power supply has negative voltage only
In telecom the positive terminal of the battery or power supply is grounded.
That makes everything powered by the -48V negative or 0 at most relative to ground, which is superior in preventing the ...
- 379k
10
votes
Accepted
Derating of C0G DC block capacitors with applied DC voltage
There are two significant misconceptions from your colleague:
Type 2 dielectrics, in general, need voltage derating, or some [fixed] ratio thereof.
All ceramic capacitors, in general, need derating.
...
- 24.3k
9
votes
Accepted
Why is the gate resistance of this PMOS so low? It should be very high
The gate resistance in this datasheet refers to the series resistance between the gate (pin) and the actual gate on the substrate.
This resistance is made up by the pin, bond wire, the substrate ...
- 4,472
6
votes
Why do my MOSFET keep blowing up saying the gate-drain voltage exceeds its rating?
Why do my MOSFET keep blowing up saying the gate-drain voltage exceeds
its rating?
You are rectifying and smoothing 220 volts. This produces a DC voltage of over 300 volts and, you are hoping to ...
- 437k
6
votes
How come negative power supply has negative voltage only
A terminal of a power supply is marked 'positive' or 'negative' depending on which terminal is taken as the reference terminal (marked 'zero').
Here's a pictorial (with batteries) for easier ...
- 16.3k
5
votes
Accepted
What does \$\mathrm{I_{D25}}\$ imply in this MOSFET datasheet?
On page 1 of the linked datasheet,
This is the rated maximum current at a case temperature of 25 °C. They're using half of that, because you don't generally run a part at its rated maximum current--...
- 28k
5
votes
Accepted
How come negative power supply has negative voltage only
A voltage source is negative or positive according to how it is measured. It has no inherent polarity of its own.
Only the terminals can have a polarity relative to another reference.
The telecom ...
- 12.9k
5
votes
How come negative power supply has negative voltage only
The importance of +48V vs -48V in the telco context is entirely related to the complete solution deployment.
The whole idea of -48V comes from the +ve terminals on the battery banks being grounded to ...
- 4,112
4
votes
Derating of C0G DC block capacitors with applied DC voltage
C0G and in general class 1 dielectric ceramic capacitors don't derate neither with temperature not bias voltage, class 2 on the other hand do, the lower the number of that dielectric the higher the ...
- 915
4
votes
Derating of C0G DC block capacitors with applied DC voltage
Murata says in their ceramic cap FAQ that C0G caps have no DC bias characteristics.
So either the caps need to be derated for other reasons, but at least they don't need derating due to capacitance ...
- 130k
4
votes
High side NPN and PNP switch
There are several topologies I try to keep in mind when using a different and higher output voltage than is being applied by an I/O pin or some other source:
simulate this circuit – Schematic ...
- 4,404
4
votes
High side NPN and PNP switch
Presumably this is what you meant to draw:
simulate this circuit – Schematic created using CircuitLab
I am assuming:
The signal at IN is a potential, either 0V or +5V
The input won't be ...
- 28.2k
4
votes
Accepted
X-ray filament and cathode connection
Is the filament connected in this manner with the cathode as shown below?
Yes
Now I know it isn't possible but I somehow connect an Ammeter at the battery end as shown below. Will I be able to get ...
- 159k
4
votes
Does turn-on and turn-off delay cause MOSFET switching loss?
As per this doc, there are no switching losses during delay time, but it can cause gate driver losses.
- 2,621
3
votes
Does turn-on and turn-off delay cause MOSFET switching loss?
No, it doesn't, and you can see in the diagram the phase difference between the voltage rising on the gate and vds, the losses you have on a transistor are the rising and falling edges where you are ...
- 915
3
votes
E series Components and Information
Resistors and capacitors are commonly given values according to an E series, as are inductors and zener diodes.
Resistors can easily be made and are often required to percent tolerances, so all values ...
- 159k
3
votes
Accepted
E series Components and Information
There is a huge amount of information available on the E "preferred values" scheme available from a simple web search. Wikipedia has a very good article.
The scheme defines spacings based ...
- 4,112
3
votes
Is it ok to short two phases of a wind turbine together through a transformer?
It's neither 'shortening', nor shorting (which is what I think you mean) the two phases, as long as the transformer has a sufficient voltage rating at the frequency the turbine is operating at. If it ...
- 159k
3
votes
Accepted
Designing boost converter for a supercapacitor source and LED load
Here is how I would do it, using a very low voltage boost regulator to pump up a 5 V rail to allow a bog-standard boost controller and external MOSFET to do the heavy lifting. For generating 5 V, ...
- 13.4k
3
votes
Accepted
Creating a test jig for a large PCB Backplate
In terms of regenerating a schematic, the netlist and parts list is the key. The manufacturer should be able to supply these if you are still having PCBs built. The combination can give you a full ...
- 4,112
3
votes
Power dissipation calculation of MOSFET: for selecting a MOSFET as Dummy load
Your circuit will operate in the linear region and this means that the gate-source voltage will be moderate to low in value and nowhere near the value to obtain lowest \$R_{DS(on)}\$ (a parameter ...
- 437k
3
votes
Why is the output current of the solar cell still continuous when using a buck converter for maximum power tracking of a solar array?
The input capacitor (1000uF in your schematic) does the trick.
When the buck FET is off, the solar cell charges the input cap. When the FET is on, it draws current both from the solar cell and the cap....
- 70.9k
2
votes
Understanding LM723-Based Variable Voltage Power Supply Schematic
In the diagram shown the key resistor is missing. You need to add a 7.5k (R6) resistor between "+" (Vp) input and GND. Also, 3.9k (R3) resistor is missing as well.
http://arduinotehniq....
- 13.7k
2
votes
Does turn-on and turn-off delay cause MOSFET switching loss?
Yes, but not in a useful way.
Two basic reasons:
Loss is not, in general, proportional to these delays.
I assume you were thinking, let's take the triangular power dissipation waveform between I rise ...
- 24.3k
2
votes
Accepted
Bootstrap in inverter circuit
There are some issues in the circuit.
The bootstrap capacitor will charge to 315 V when low side output MOSFET is activated, so it will destroy high side MOSFET`s gate. The negative terminal of power ...
- 1,274
2
votes
Why is a class A amplifier with load cooler than without load?
Why is a class A amplifier cooler with load than without load?
In the so-called class A amplifier, the collector-emitter part of a transistor Q and collector resistor Rc are connected in a voltage ...
- 13.9k
2
votes
Accepted
Identifying these ICs
The top ones markings match with a TMI (拓尔微) TMI3244T step-down converter.
(Source: szlcsc.com)
The bottom ones markings matches with a Fitipower FR9205 step-down converter.
(source: lcsc.com)
- 2,751
2
votes
Accepted
Voltage not varying with duty cycle
I don’t know what's the error as I have seen in buck converter that with a capacitor in path of the PWM, as the duty cycle changes the voltage changes. Using that concept of buck converter and voltage ...
- 20.3k
2
votes
Turns of inductor relation with phase shift
Inductors follow the equation $$V=L*di/dt$$
That shows where the 90 degree phase shift for sinusoids comes from, the voltage is proportional to the derivative of the current, or the current to the ...
- 23.1k
2
votes
Accepted
How can you calculate Peak Pulse Power for a Non-Rectangular Power Pulse
The same document explains this on item 4:
So, you need to write the voltage's equation and solve the energy integral:
$$
E = \int_{T1}^{T2}p(t) \ dt
$$
If you have \$p(t)\$ put it directly. If you ...
- 27.5k
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