Troubleshooting Circuit with TL594: Output of 10kHz"

In summary, the conversation discusses the setup of a circuit and the issues faced by the person. They mention their frequency requirement, use of a formula from a datasheet, and their oscilloscope results. They also mention their use of a potentiometer and their struggle with adjusting the duty cycle. They provide a schematic and ask for advice on determining a ferrite core transformer. The conversation then goes into detail about experimenting with different components and adding rectifiers to the circuit. The purpose of the transformer is also discussed, as well as a recommendation for a specific transformer. The conversation ends with a question about choosing between two circuits and a request for further assistance.
  • #1
billy fok
40
0
i have set up the circuit, but i do have some problem that i can't figure it out..

  • my frequency requirement is 20khz, i do follow the formula that the data sheet given, base on my oscilloscope, it shown 10khz.. capacitor voltage is 0.01 micro. resistor value is 5.5k ohms.
  • when i connect the the potentiometer, i can't adjust the duty cycle at all..
I have attach
  • my circuit output oscilloscope result.
  • circuit that i set up
  • and datasheet, it content the formula that i use..
data sheet for TL594
please give me some advice on this..
 

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  • #3
explain pls
 
  • #4
billy fok said:
explain pls
I just got you a schematic that works. Start with that and experiment with component values.
 
  • #5
so the output will be pwm signal and i able to adjust the duty cycle?
 
  • #6
billy fok said:
so the output will be pwm signal and i able to adjust the duty cycle?
Try!
 
  • #7
hi

may I know how to determine the ferrite core transformer? pls help
 
  • #9
First, build everything to the left - No MOSFETS / transformer...
Spend time with the resulting circuit until you are satisfied it's working. Then, add the MOSFETS with transformer, but no output rectifiers. Be careful as you explore this configuration as the mosfets are likely to be damaged by small errors.

For the transformer, I would look up coiltronic's VersaPak. These are designed to help beginners get working power supplies and have support documents.

With the transformer, but no rectifiers, study the voltage waveforms on the drain of each MOSFET. You will see voltage spikes when each MOSFET is turned off. Adding a resistive load to the output of the transformer, you'll see these spikes become worse. What you're seeing is the energy stored in the leakage inductance of the transformer. Search under the word snubber to find circuits that can absorb the energy so that it doesn't harm your mosfets.

Next, add your rectifiers. There are issues with rectifiers in that they don't turn off immediately and this will cause ringing and voltage spikes. Again, snubbers across your rectifiers will help. Also, experiment with the rectifiers. Different ones behave radically different.

Spend time, pace yourself, and this circuit can bring a great deal of wisdom :-)
 
  • #10
it can fit for closed loop right??
 
  • #12
billy fok said:
hi. i suppose to choose dc-dc transformer?
Yes.
 
  • #13
Svein said:
Yes.
base on the circuit, what is voltage error? is a diode or?
 
  • #14
billy fok said:
what is voltage error? is a diode or?
The symbol indicates a LED.
 
  • #15
Svein said:
The symbol indicates a LED.
may i know what is the purpose of the transformer??
 
  • #16
billy fok said:
may i know what is the purpose of the transformer??
  1. Galvanic isolation (no wires between the output voltage and the inputs)
  2. The circuit will not work without a transformer.
 
  • #17
Svein said:
  1. Galvanic isolation (no wires between the output voltage and the inputs)
  2. The circuit will not work without a transformer.

hi... i just build up the circuit without the mosfet. am i alright to say that, there will be not output at all?
would you mind recommend 1 transformer to me? I been looking the transformer that you recommend to me. i should be looking at the DC-DC transformer. and 30 Watt POE+ Power Transformers For Akros Silicon AS1135 will be my choice...

can i choose circuit B?

Hope hear from you soon!
 

What is the purpose of the TL594?

The TL594 is a pulse-width modulation (PWM) controller that is used to regulate the output voltage of a circuit. It is commonly used in power supply circuits and motor control circuits.

Why is the output of the TL594 set at 10kHz?

The output frequency of the TL594 is typically set at 10kHz because it is a commonly used frequency for power supply and motor control applications. This frequency allows for efficient switching and smooth regulation of the output voltage.

What could be causing a circuit with a TL594 to have a faulty 10kHz output?

There are several potential causes for a faulty 10kHz output in a circuit with a TL594. It could be due to a malfunctioning TL594 chip, incorrect wiring or connections, faulty components in the circuit, or incorrect values of external components such as resistors or capacitors.

How can I troubleshoot a circuit with a TL594 if the 10kHz output is not working?

To troubleshoot a circuit with a TL594, you can start by checking all connections and ensuring they are correct. Then, check the values of external components to make sure they are within the recommended range. You can also test the TL594 chip itself for any malfunctions. If necessary, you may need to replace components or consult a schematic for further troubleshooting.

Are there any common mistakes to watch out for when using a TL594 in a circuit?

One common mistake when using a TL594 is incorrect wiring or connections. Make sure to double-check all connections and follow the recommended schematic for the circuit. Another mistake to watch out for is using incorrect values for external components, which can affect the output frequency and voltage. It is also important to properly design the feedback loop to ensure stable operation of the TL594.

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