Mosfet driver inverting/non-inverting questions.

[Rubicon]

Hello,

I have am a little confused here about the inverting and non-inverting

mosfet drivers TC4429 and TC4420.

*********************************
From the Microchip datasheet:
The TC4429 is an inverting driver (pin-compatible
with the TC429), while the TC4420 is a non-inverting driver.
*********************************

Yet when I look at the functional block diagram of both types the
inverting 4429 has an inverter followed by another inverter so then it
must be a non-inverting driver and as the non-inverting 4420 has only
the latter inverter it must be an inverting driver. Is this correct or
am I reading it completely wrong?

www.ortodoxism.ro/datasheets/microchip/21419b.pdf

In addition if using a Microchip PIC to PWM a TC4429 (actually?)
inverting driver (the only mosfet driver I can find locally) that
contols a N-channel mosfet that controls a motor wouldn't you need to
reverse the PWM values and to keep the I/O pin high when not wanting
the motor on?

Any help appreciated.

Regards,

Andrew.

 

[poogie]

Hello,

I have am a little confused here about the inverting and non-inverting

mosfet drivers TC4429 and TC4420.

*********************************
From the Microchip datasheet:
The TC4429 is an inverting driver (pin-compatible
with the TC429), while the TC4420 is a non-inverting driver.
*********************************

Yet when I look at the functional block diagram of both types the
inverting 4429 has an inverter followed by another inverter so then it
must be a non-inverting driver and as the non-inverting 4420 has only
the latter inverter it must be an inverting driver. Is this correct or
am I reading it completely wrong?

www.ortodoxism.ro/datasheets/microchip/21419b.pdf

In addition if using a Microchip PIC to PWM a TC4429 (actually?)
inverting driver (the only mosfet driver I can find locally) that
contols a N-channel mosfet that controls a motor wouldn't you need to
reverse the PWM values and to keep the I/O pin high when not wanting
the motor on?

Any help appreciated.

Regards,

Andrew.

If I understand this correctly and the way I see the diagram, it is
correct. Did you take into account the final FET stage shifting the
signal 180 degrees from the input. As for putting another N Channel,
is it possible to use an inverter on the input of the TC4429 achieving
the same final result?
Let me know if I am understanding this right!
Poogie

 

[Rubicon]

If I understand this correctly and the way I see the diagram, it is
correct. Did you take into account the final FET stage shifting the
signal 180 degrees from the input. As for putting another N Channel,
is it possible to use an inverter on the input of the TC4429 achieving
the same final result?
Let me know if I am understanding this right!
Poogie

Poogie,

Sorry I didn't take that into account and you are quite correct an
inverter at the input would achieve the final result.

Silly to post when I'm tired.

Regards,

Andrew.

 

[Clint Sharp]

Hello,

I have am a little confused here about the inverting and non-inverting

mosfet drivers TC4429 and TC4420.
Yet when I look at the functional block diagram of both types the
inverting 4429 has an inverter followed by another inverter so then it
must be a non-inverting driver and as the non-inverting 4420 has only
the latter inverter it must be an inverting driver. Is this correct or
am I reading it completely wrong?

Umm, my understanding of the block diagram is that the 4429 has three
inverters, the input looks like a schmitt input NAND gate with both
inputs wired together, therefore an inverter. The 4420 has only the NAND
and the inverter so that's 'true' logic. Maybe I'm missing something as
well but that's how I'd read it?

 

[Rubicon]

Umm, my understanding of the block diagram is that the 4429 has three
inverters, the input looks like a schmitt input NAND gate with both
inputs wired together, therefore an inverter. The 4420 has only the NAND
and the inverter so that's 'true' logic. Maybe I'm missing something as
well but that's how I'd read it?

Clint.

Thankyou for your post.

Regards,

Andrew.