I was concerned I was getting noise from a switching power supply, so that is why V1 is a battery. I thought perhaps that voltage induced into the circuit from XFMR1 was causing issues, so I disconnected the supply from V1. The duty cycle does not change. I scoped V1 and V2 and found noise. There is also noise on the ramp oscillator, one leg of C2.
I also added a 20nF cap to V1 down on the board. I've also tried temporarily adding other capacitors of various values with no change. All the way from 10 pF up to 47 nF. Is the noise in the circuit the cause of this, or should I be checking elsewhere? What are the possible sources of the noise in this circuit?
So this circuit is only charging and discharging the gates. This should eliminate the opportunity for any noise induced the from high currents in the gate circuits. I measured the emitters of the TL directly with my scope. I see the same behavior, so something other than noise from the gate current is preventing the correct operation of the TL Pretty much what I'd expect from breadboard - you are seeing 0V bounce and that will likely be the high currents inducing voltages in the large loop formed by the scope probe and it's respective earth wire.
A really common problem faced when doing switch mode supplies. Here is a picture of what some folk do to avoid this problem: -. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Intended output power is w.
Sorry for lack of knowledge. How do you calculate the gain? And what does it refer to? So my problem so far seems to be input cable! Voltage drops on 1 ohm cable before it reaches to input terminal. I am going to use smaller cable next time. Site Search User. Power management Power management forum. Mentions Tags More Cancel. Ask a related question What is a related question?
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Tags More Cancel. Share More Cancel. Similar topics. This thread has been locked. Prodigy 30 points. This table lists the pin configuration of the pulse width modulation control circuit. As mentioned earlier, it is a fixed frequency and variable duty cycle dual PWM control circuit.
It does not require any external components to operate except a few resistors and capacitors for an oscillator. This oscillator is responsible for generating a sawtooth waveform according to timing capacitor C T. This TL IC generates signals by comparing a sawtooth waveform with two control signals of the error amplifiers. The output signal will be on during the time when sawtooth voltage is greater than the voltage at error amplifiers outputs.
You can see a block diagram given above. In the last section, we see that the oscillator is mainly responsible for generating sawtooth waveform. This sawtooth waveform used for deadtime control and PWM comparator amplifiers. Therefore, the frequency of the oscillator determines the frequency of output signals. Now, we will see how to choose the frequency of an oscillator. We can select frequency by selecting suitable values of R T resistor and C T capacitor.
We can select the capacitor and resistor values according to this formula:. First, we will see a simple example to generate pulse width modulation signals from this IC. After that, a practical example provides a circuit diagram of a buck converter. Below circuit diagram can be used to generate 2 PWM signals. The width of each PWM can be controlled through these variable resistors. We have designed a buck converter using TL as an example. Input to buck converter is 25 volt and output is in the range of 7 to 19 volts.
Users can change the output voltage with the help of the variable resistor shown in the circuit diagram below. TIP is used as a switching device.
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