# Irf630

Discussion in 'General Electronics Chat' started by Dritech, Apr 13, 2012.

1. ### Dritech Thread Starter Active Member

Joined:
Sep 21, 2011
678
4
Hi,

What is the voltage drop between the drain and the collector of the IRF630??

I cannot see this specification listed in the datasheet.

2. ### k7elp60 Active Member

Joined:
Nov 4, 2008
427
63
I think you mean the drain and the source, as the drain is like a collector of a transistor. The difference is dependant on the drain current times the Rds(On resistance) This depends upon the gate to source voltage. The Rds is typically 0.25ohms.

3. ### MrChips Moderator

Joined:
Oct 2, 2009
11,765
3,025
IRF630 is a power MOSFET, not a bipolar junction transistor.
There is no collector, only gate, drain and source.
The drain-source ON resistance is 0.4 ohm max.

4. ### paulktreg Well-Known Member

Joined:
Jun 2, 2008
542
99
I don't think you will find it quoted?

It does however have a RDS(on) resistance of 0.35R. If you know how much current is flowing through the device then Ohms Law will give you the voltage across it.

or is this too simplistic?

Hope that helps.

5. ### Dritech Thread Starter Active Member

Joined:
Sep 21, 2011
678
4
Hi, thanks for the replies. Why the TIP122 and similar transistors have the 'Collector-Emitter Saturation Voltage' listed while the MOSFETs do not have?

6. ### Dritech Thread Starter Active Member

Joined:
Sep 21, 2011
678
4
So if the current flowwing through a MOSFET with an RDS(on) resistance of 0.35R, is voltage drop is 0.35*2A = 0.7V. Is that how to determine the voltage drop?

7. ### paulktreg Well-Known Member

Joined:
Jun 2, 2008
542
99
There are a few manufacturers of the IRF630 with different quoted values for RDS(on) so check that first but your calculation sounds right to me.