Hello,
I have looked for the timing formula and found it in a datasheet from ST.
Greetings,
Bertus
I have looked for the timing formula and found it in a datasheet from ST.
Greetings,
Bertus
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Sir, you are right I will use it to make a linear type Modified Sine wave inverter (together with a NOR gate to make a stepped-square wave).I think that you can attempt to derive a formula all that you wish, but at best "your mileage will vary".
I looked at a datasheet I downloaded from ST Microelectronics. It doesn't have a formula either; two separate charts for charge and discharge times.
The recommended oscillator frequency range is from 100Hz to 400kHz. You are attempting to operate this IC at the extreme lower end of the recommended range.
I suspect that the charge/discharge response curves will tend to vary significantly over temperature when you're running the IC at nearly minimum or nearly maximum frequencies. You will have to verify operation by testing.
It wasn't designed to be a precision oscillator; merely oscillate in a ballpark range.
It sounds to me like you're trying to build a UPS or inverter. That isn't what the IC was designed for. It was designed for use as a building block in a DC-DC switching power supply.
Sir, I think the RD is also used so that OUTPUT A & B never "ON" at the same time.. so, RD must NOT kept at ZERO?The fly in the ointment is that Discharge time varies with Rd (deadtime) as shown in Figure 2. For example, for a 2-uS discharge time, Ct varies by an order of magnitude. If Rd is kept at zero, then one can probably calculate a simple relationship, as is shown for similar chips. The LM3524 oscillator is simply 1/RC.
John
Hi Audioguru.. ^_^A metalized plastic film capacitor is availabe in a 5% tolerance for a low price.
In the Orient they are called a "green cap" and the letter J is 5% tolerance.
A 0.1uF, 5% is labelled "104J".
A Mylar capacitor uses a metalized polyester fim made by Dupont. Other plastics companies also make the same plastic film but call it a different name.A metalized plastic film capacitor have a the same characteristics as the MYLAR (polyester-film) capacitor? ...'coz I saw some MYLAR with a label just like this "104J".. or a metalized plastic film capacitor is more stable?
I didn't look at its datasheet but I think the SG3525 is about the same as a TL494.BTW, do you think I can use the error amp. of SG3525 for voltage regulation? ...I mean to compensate for battery voltage variation. And I will use SG3525 together with a Logic gate to have a stepped-square wave. I think using this IC, "shoot-through" can be prevent.
A Mylar capacitor uses a metalized polyester fim made by Dupont. Other plastics companies also make the same plastic film but call it a different name.
I didn't look at its datasheet but I think the SG3525 is about the same as a TL494.
Sir, how about a Ceramic capacitor with the same tolerance (±5%) ?
I did not say RD should be zero. I was referring to the original datasheet that showed typical frequencies with RD set to zero. As I recall, the previous posts didn't mention what value you were considering for RD either.Sir, I think the RD is also used so that OUTPUT A & B never "ON" at the same time.. so, RD must NOT kept at ZERO?
I am not a SIR because I was not knighted by the old Queen.Sir, how about a Ceramic capacitor with the same tolerance (±5%) ?
Thank you Sir.. ^_^Hello,
I think your circuit will not regulate.
You are not looking at the wanted voltage to be regulated.
You have created some kind of shutdown circuit now.
Greetings,
Bertus
You mean something like this ?Hello,
You must compare the battery voltage to a deriviate of the output voltage to regulate.
You can do this with an extra winding on the transformer, rectify the voltage from this winding and put an elco on it to obtain a DC voltage that follows the output voltage.
This DC voltage can be used to regulate the output.
(you quit often see this is smps systems).
Greetings,
Bertus