From what I remember of the Max621 datasheet, it provides a gate drive of Vcc + about 10V. The gate voltage it provides is independent of the voltage you attach to the load and mosfet. Thus, it should work with either 5 or 12 volts. Be sure your motor gives the power you need at 5V, though.

The bertus circuit will not work with only 5V attached to the load, because it does not include any method to increase the voltage to the 8 to 10 volts you need at the mosfet gate.

John

 

the load is attached to 12V lead acid battery.
Just to clarify:
The electronics is fed by a +5v supply.
The load is attached to 12V

hence can the mosfet be fed 10V via the MAX621 if the MAX621 rail voltage is only +5V?
This is the question I really need to understand.
Cheers

 

That is exactly what the datasheet for the Max621 says it does:

John

 

Thanks for that, I think this is now cleared up any misconceptions I had.

 

I just noticed that the Max622 does the same thing and comes in an 8-pin package. If you don't need the four channels, it would save some space.

John

 

Hi, Does anyone know of a Quad version of the MAX621 ? I have a 3 stage inductive load to switch.

 

Hi, Does anyone know of a Quad version of the MAX621 ? I have a 3 stage inductive load to switch.

 

Also I cannot locate one from a local supplier.... I use mouser.com.
Any suggestions from this would be great.

 

Also I cannot locate one from a local supplier.... I use mouser.com.
Any suggestions from this would be great.

 

The Max621 is a quad, i.e., 4 outputs. What do you mean by "quad?"

John

 

4 outputs yes. but cannot find one in NZ is there an equivalent?
Blair - NZ

 

4 outputs for clarification - Sorry after an alternative as local suppliers don't stock.
mouser.com - supplier

 

4 outputs for clarification - Sorry after an alternative as local suppliers don't stock.
mouser.com - supplier

 

Hello,

Digikey seems to sell it.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MAX621CPN-ND
Unfortunately none in stock.

Greetings,
Bertus

 

This is one case where DigiKey may not be the best bet. The NZ site shows the price as $14,209.86 in lots of 1000 plus shipping. Those must be NZ dollars. In the US it is only a bit more than $6,000.00 for 1000.

It is also not RoHS compliant.

John

 

Phew and I thought it was gonnna be expensive

Is there an alternative to this though? I

 

Ok guys, I think I've nailed it: sn75374
Any feedback muchly appreciated by all you guru's out there...

 

however this has no pump.....

So back to square one....help!!

 

or this one? TC4420

 

Please note the supply is +5v and will the output be pumped to +10V?