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how to connect between irf740 and tlp250

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alinpy

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can anybody tell how to connect between irf740 and tlp250.
 

yes......to drive mosfet irf740 with tlp250
 

you can have look at this -
**broken link removed**
you can replace the pwm controller by your opto-coupler...should work for you

Good Luck
 
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    alinpy

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Dear friends!
Hi
If your GS junction connect to the +15 volt , it will be turn on . if you turn on the LED of that opto coupler , its out put will be about vcc ( such as +15 volts) . and you should give its out put to the gate of your mosfet instead of source . you should be ensure that the voltage across the GS junction is some thing like +15 volts ( exactly).
Best Wishes
Goldsmith
 
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    alinpy

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This is the typical connection:


eg. Input + could be a signal coming from a PWM chip, a microcontroller or any circuitry needing to turn the MOSFET on. Input - could be connected to the ground to which that circuitry is connected to.

You can help other types of loads as well, like inductive. If you have a motor or relay, connect an anti-parallel diode across that relay.

Hope this helps.
Tahmid.
 
Tahmid said:
This is the typical connection:


eg. Input + could be a signal coming from a PWM chip, a microcontroller or any circuitry needing to turn the MOSFET on. Input - could be connected to the ground to which that circuitry is connected to.

You can help other types of loads as well, like inductive. If you have a motor or relay, connect an anti-parallel diode across that relay.

Hope this helps.
Tahmid.
Click to expand...

In the circuit diagram using TLP250 as gate drive opto-isolator driving IRF740, whether at output of TLP250 pull-up resistor is required or not.
 

Hi my friend!
Is your mean by the out put resistor , the series resistor with the gate of your mosfet? if yes , yes it is important and it will have low value , to limit the gate current.
Best Wishes
Goldsmith
 

The output of TLP250 does not need a pull-up because the output stage of the TLP250 is a totem-pole stage. Plus, having a pull-up would be bad, since, when TLP250 is off, MOSFET would be on. This isn't required at all since TLP250 has a totem-pole output stage. However, a pull-down resistor has been provided from gate to source of the MOSFET to prevent it from accidental turn-on under any circumstance.

Hope this helps.
Tahmid.
 
Somebody please tell me what is the use of that 1K resistor connected between the mosfet gate and ground?

- - - Updated - - -

Tahmid said:
The output of TLP250 does not need a pull-up because the output stage of the TLP250 is a totem-pole stage. Plus, having a pull-up would be bad, since, when TLP250 is off, MOSFET would be on. This isn't required at all since TLP250 has a totem-pole output stage. However, a pull-down resistor has been provided from gate to source of the MOSFET to prevent it from accidental turn-on under any circumstance.

Hope this helps.
Tahmid.
Click to expand...

Can you explain more on this? How does it turn on accidentally?
 

vinu gopalakrishnan said:
Can you explain more on this? How does it turn on accidentally?
Click to expand...

Due to noise. And the internal drain-to-gate "Miller capacitance". A similar experience is narrated in Sanajaya Maniktala's "Switching Power Supplies A to Z". This is also talked of in Raymond Mack's "Switching Power Supplies Demystified".

Hope this helps.
Tahmid.
 
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