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# Power Supply operating frequency

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#### saumya_85

Power supply operates at 55KHz. What does it mean?

I think, It gives DC out put at 55KHz. Am I correct?

A power supply operating at 55 kHz refers to the switching frequency of the (switching) voltage supply regulator. There are two basic types of voltage regulators: linear and switching regulators. A basic switching regulator is some combination of diodes, capacitors, transistor switches and inductors. The speed and duty cycle of the transistor switches determine the DC output value. For your case, the transistors switch at 55 kHz. The power supply gives out a DC output. That means there is not any frequency except for the voltage ripple in the output.

See the book called "Switching Power Supply Design" by Abraham Pressman.

hope that helps,
Matthew

tiger135

### tiger135

Points: 2
V
Points: 2
The 55KHz is the switching frequency of the internal circuit of power supply. The DC output will be filtered and will be DC, ie:0Hz.

saumya_85

### saumya_85

Points: 2
Here I have attached the schematic. It Viper20 based PSU.
I want to measure switching frequency.

Which point I should measure.

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The SW line

saumya_85

### saumya_85

Points: 2
Thank you. One is the SW Line and with reference to which point
The SW line

Use a scope with the probe on SW and the ground clip on Ground.

---------- Post added at 18:15 ---------- Previous post was at 18:15 ----------

Use a scope with the probe on SW and the ground clip on RTN. (Ground).

saumya_85

### saumya_85

Points: 2
A higher switching frequency permits using smaller components. Particularly the coil. Thus the supply costs less to manufacture.

The designer constructs the prototype circuit. Then he adjusts it to yield maximum current output. One way is to use a high enough frequency to get maximum throughput of joules in and out of the inductor.

saumya_85

### saumya_85

Points: 2
A higher switching frequency permits using smaller components...

The concepts is like energy-packs.
At higher switching frequencies coil require carry less energy per time.

+++

Points: 2

Points: 2