TPS40210 output variation 100V Ok 50V needed

sakthivel s

Other Parts Discussed in Thread: TINA-TIhi,
I have done circuit for 100 Vdc with 12 V input. now i have a doubt
1. is it possible to get 50V with same circuit. if yes what should i do weather introduce voltage divider into the output Or need to make change in switching function
2. I have tried with voltage divider in simulation i am getting exactly 50 V as a output but when we introduce voltage divider for high voltage circuit produce high heat. so what is possibility to get 50 V.
3. if need to change in switching circuit how to do that.

over 8 years ago

0 sakthivel s over 8 years ago

Intellectual 620 points

1. what is the relation between switching frequency and output voltage.

2. how to set the switching frequency in same circuit using Micro controller.

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

Generally, output voltage is independent of switching frequency. Only the duty cycle is changed for different Vout. It is controlled by the voltage divider in the feedback path. Do you need to switch between two different output voltages of 50 V or 100 V?

0 sakthivel s over 8 years ago in reply to JohnTucker

Intellectual 620 points

yes sir, i want switch between 50 V or 100V

0 sakthivel s over 8 years ago in reply to sakthivel s

Intellectual 620 points

sir,
when i am changing the feedback resistor Rfb1 to 730ohm then i am getting 50 V as per simulation. Is it enough to get 50 V with the same circuit in PCB.?

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

Many of the equations used to determine external components depend on output voltage. So for both 50V and 100 V output, you will need to find compromise values that will work for both. You could possibly simulate both circuits in webench, then adjust the external components so they are the same for both and see if webench suggests any trouble areas.

0 sakthivel s over 8 years ago in reply to JohnTucker

Intellectual 620 points

sir,
I have simulated both the circuit in WEBENCH and compared to 50 V to 100 V. they modified switching frequency based on inductor, diode and RC values. but in my case i want both voltage in same circuit with same switching frequency. so that only i fixed feedback voltage is good as per your suggestion and i simulated in TINA-TI i got expected output also.

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

Ok,then are you set?

0 sakthivel s over 8 years ago in reply to JohnTucker

Intellectual 620 points

Sir,

I am going set feedback resister Rfb1..as variable

0 sakthivel s over 8 years ago in reply to sakthivel s

Intellectual 620 points

sir,

what is relation between input voltage and output voltage in DC-DC boost converter. if we change input what will be the output.

0 sakthivel s over 8 years ago in reply to sakthivel s

Intellectual 620 points

sir,
please give me a formula for switching frequency

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

The relationship between Vin, Vout and duty cycle is explained in the datasheet, section 7.3.4 starting on page 14. the equation 14 is used to determine Rt that determines the switching frequency ion page 15.

0 sakthivel s over 8 years ago in reply to sakthivel s

Intellectual 620 points

sir,

As per WEBENCH the value of Rrc=0.511 Mohm and Crc= 100 pf when switching frequency is 319.105 Khz. but, as per formula same switching frequency and Crc value of Rrc will be 0.0123 ohm.

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

You must be making a mistake somewhere. The Rrc will never be such a low value.

0 sakthivel s over 8 years ago in reply to sakthivel s

Intellectual 620 points

sir,
when design a 12 V to 100 V 0.1 A DC boost converter circuit in WEBENCH. After simulation i am getting a document related to entire circuit components, input and output voltage and also power dissipation.
my doubt is in that document they are given power dissipation of IC, diode,MOSFET,inductor, diode and also total power dissipation. here how to calculate total power dissipation and what basis they given my circuit power dissipation is 761.383 mW.

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

Not sure what your question is. can you re state it?

0 sakthivel s over 8 years ago in reply to JohnTucker

Intellectual 620 points

sir,
How WEBENCH calculated power dissipation of the DC-DC converter circuit. on what basis they mentioned 761.383 mW for my circuit.

0 JohnTucker over 8 years ago in reply to sakthivel s

TI__Guru**** 191445 points

That is calculated internally. I don't think we can provide the details. For most converters, it is adjusted to closely match the measured power dissipation form several reference designs. From my experience, it is pretty accurate. I think they target +/- 4% accuracy.

0 sakthivel s over 8 years ago in reply to JohnTucker

Intellectual 620 points

sir,

What are all possibilities to get negative 50 V output with positive input. which IC i have use for that.

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TPS40210 output variation 100V Ok 50V needed