Ground isn't negative. It's at 0v.
If you set pin 4 above ground, you limit the maximum duty cycle. Ideally it's grounded if you don't need deadtime (you should not). The rc combination you chose limits the duty cycle to about 45%
Remove the pot and connect the pins as suggested in post 9.
Do the FETs heat up?
What is the output voltage?
If you set pin 4 above ground, you limit the maximum duty cycle. Ideally it's grounded if you don't need deadtime (you should not). The rc combination you chose limits the duty cycle to about 45%
Remove the pot and connect the pins as suggested in post 9.
Do the FETs heat up?
What is the output voltage?
Do you mean that the input voltage is equal to vref?
Inside the datasheet, the voltage of the vref pin is 5 volts.
It is 4.97 volts in my circuit.
With a 12 volt input
Duty cycle is not 50%
How do I equal these two voltages?
Yes
pin4 connected ground and Dutycycle is not 50%
the FETs heat up(The temperature of one of the mosfets is higher)
output voltage is 229V ac now(thats my needed voltage)
i can't set up feedback, deadtime, and Dutycycle for a few days.
i am having trouble analyzing these three sections.
Can you draw a schematic?
For my work, 50% duty cycle is required
with a small amount of Deadtime that does not interfere with two waves (47 ohm resistor in 3525 had a good deadtime)
(in the research I have done all the cores with dead time Zero can not work)
and feedback is not using an opamp ( Out Switching Voltage is not double)I mean output voltage is 0 +229,not +115 0 -115
I use toroid core
Does the feedback work well with this voltage(320Vdc)?
If the two input voltages reach the comparator to one level, does the output compare to zero?
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A true 50% duty cycle isn't generally practical.
What toroid are you using?
How long does it take for the FETs to heat to a point where you cannot touch it?
4 FETs and only one heats up?
Much of this is covered on the power supply design page of my site, have you read it?
Click ---> Basic Switching Power Supply Design Tutorial
What toroid are you using?
How long does it take for the FETs to heat to a point where you cannot touch it?
4 FETs and only one heats up?
Much of this is covered on the power supply design page of my site, have you read it?
Click ---> Basic Switching Power Supply Design Tutorial
i use or38 core
internal diameter 25mm
external diameter 40 cm
about 5 to 10min
no i use just one irfz44 on the even output of TL494
thats just for test
one of the tl494 output 9.6 v and the other 6.6volt(duty cycle is not 45 50%)
yes
They were great. i read them.
Thank you for the information you provided on your site
but I had a problem again.
Its first time that i use this ic for SMPS(i used sg3525)
Please draw for me a schematic to prepare it's board and getting the IC's part work better
With the information I have, I can not currently design what I need.
i need help
internal diameter 25mm
external diameter 40 cm
about 5 to 10min
no i use just one irfz44 on the even output of TL494
thats just for test
one of the tl494 output 9.6 v and the other 6.6volt(duty cycle is not 45 50%)
yes
They were great. i read them.
Thank you for the information you provided on your site
but I had a problem again.
Its first time that i use this ic for SMPS(i used sg3525)
Please draw for me a schematic to prepare it's board and getting the IC's part work better
With the information I have, I can not currently design what I need.
i need help
Ferrite isn't specific. There are various ferrite materials and they perform differently. What's the 'initial permeability' spec of the core material you're using?
Is the heating of the FETs less if you use a 20k ohm timing resistor?
Is the heating of the FETs less if you use a 20k ohm timing resistor?
Perry has probably nailed it, the core material has to be chosen very carefully so that Bt is not exceeded. You can get away with 1000mT but 320mT is better for reliability. Cheap Chinese transformers run hotter because Bt is too high. Military transformers are usually specified with lower saturation for reliability.
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Unfortunately, I do not have the more details of the core material
yes.
I read your site content and datasheet again.
in this Address:
http://www.bcae1.com/switchingpowersupplydesign/tl594demo03.swf
when pin 4 have 1.4v dutycycle about 50%(every output 25%)
and when two input from comparator have same voltage,ic turned off
it means that the IC constantly turning off/on at high speed?
Deadtime is Fixed but how ic try to compensate for voltage drop?
Having unconnected inputs (15 and 16) can cause unforeseen problems. I would connect 15 to 14. Ground pin 16.
Why do you feel the need to have pin 4 off of ground?
The input to pin 1 from the output of the supply will compensate for drop at the output.
The input to pin 1 needs to be rectified.
Is the reason for this supply to drive a lamp and nothing else?
Why do you feel the need to have pin 4 off of ground?
The input to pin 1 from the output of the supply will compensate for drop at the output.
The input to pin 1 needs to be rectified.
Is the reason for this supply to drive a lamp and nothing else?
ok i connecting Pin 15 and 16 to 14 and gnd (like the one on your site)
Do not need this connection to pin4?
you say when pin4 connected to gnd dutycycle is Maximum.
i think you mean that maximum dutycycle is 100%
I just want to set the dutycycle to 45 50%.
If I do not receive feedback from the output, how do I set up the feedback?
The input to the pin 1 is Rectifier
The bulb is more often connected to this smps.
My assumption is that the comparator only gives the ignition ON and OFF
If this is the case, the dutycycle works with a predetermined value and I think it can not compensate for the drop.
Do not need this connection to pin4?
you say when pin4 connected to gnd dutycycle is Maximum.
i think you mean that maximum dutycycle is 100%
I just want to set the dutycycle to 45 50%.
If I do not receive feedback from the output, how do I set up the feedback?
The input to the pin 1 is Rectifier
The bulb is more often connected to this smps.
My assumption is that the comparator only gives the ignition ON and OFF
If this is the case, the dutycycle works with a predetermined value and I think it can not compensate for the drop.
The maximum duty cycle is limited to less than 50% for each output when pin 13 is connected to pin 14.
If the drive circuit between the output of the IC and the FETs, you do not need any deadtime for most supply configurations. For MANY supplies, pin 4 is grounded.
You need feedback from the output but if you have non-rectified output, you risk getting negative back to the input of the 494 which can cause it to malfunction.
When the output feedback to pin 1 matches the voltage on pin 2, the IC rolls back the duty cycle. The operation is so fast that there isn't any on/off. For amps that use this, the duty cycle will change very quickly as the demands on the supply change and the voltage on pin 1 will remain unchanged. The operation is VERY fast, virtually seamless.
If the drive circuit between the output of the IC and the FETs, you do not need any deadtime for most supply configurations. For MANY supplies, pin 4 is grounded.
You need feedback from the output but if you have non-rectified output, you risk getting negative back to the input of the 494 which can cause it to malfunction.
When the output feedback to pin 1 matches the voltage on pin 2, the IC rolls back the duty cycle. The operation is so fast that there isn't any on/off. For amps that use this, the duty cycle will change very quickly as the demands on the supply change and the voltage on pin 1 will remain unchanged. The operation is VERY fast, virtually seamless.
Hi
I made a SMPS For test without feedback.
It works good.
output +-32v 100w
i use 0.5mm wire for core but i like to use 1 or 0.7mm wire for winding core
to have less layer of wires
they have skin effect
(my Frequency is 30khz)
i like to winding core like car amp smps
I made a SMPS For test without feedback.
It works good.
output +-32v 100w
i use 0.5mm wire for core but i like to use 1 or 0.7mm wire for winding core
to have less layer of wires
they have skin effect
(my Frequency is 30khz)
i like to winding core like car amp smps
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