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Low power Transistor or MOSFET ??

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Gayan Soyza

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Low Power BJT or MOSFET ??

I need to replace standard NPN transistors (with additional base resisters) with a single MOSFET to work with 2.4V-4.8V (batteries).

I'm planing to place 2N7000.Data sheet says its designed for low power applications but looks likes it needs 2.1V Ggs.

Anybody have worked with this MOSFET with low voltage range like 2.4V-4.8V??
 
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I need to replace standard NPN transistors (with additional base resisters) with a single MOSFET to work with 2.4V-4.8V (batteries).

I'm planing to place 2N7000.Data sheet says its designed for low power applications but looks likes it needs 2.1V Ggs.

Anybody have worked with this MOSFET with low voltage range like 2.4V-4.8V??

hi Gayan,
I often use these in conjunction with TTL/PIC's, CMOS, OPA's etc with a 5V supply. no problems.
It really depends upon what the 2N7000 is being used for, eg Ids range.?
 
Hi Eric Thanks for your input.

I need to light up my 5X7 LED small matrix system.

In that matrix one LED takes 22mA current.I need to drive one column of LEDs (7 LEDs) with this 2N7000.So for 5 columns I need 5 MOSFETS.
 
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Hi Eric Thanks for your input.

I need to light up my 5X7 LED small matrix system.

In that matrix one LED takes 22mA current.I need to drive one column of LEDs (7 LEDs) with this 2N7000.So for 5 columns I need 5 MOSFETS.

hi,
That should be OK.
 

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Hi Eric thats a nice graph thanks.

The thing is my project is battery operated.From the graph below 3.5V is not going to provide sufficient current.

hi,
Whats the driving source for the 2N7000 gates are you using a PIC or some other ic.?
Whats the project.?:)
 
hi,
Whats the driving source for the 2N7000 gates are you using a PIC or some other ic.?
Whats the project.?:)

Its a mini 5X7 LED matrix project.I'm using a PIC.

Most important thing is this must power from batteries.

This is a hand held project so it must use batteries.To make the design compact I planned to use MOSFETS instead of BJTs.So I can eliminate base resisters as well.
 
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Its a mini 5X7 LED matrix project.I'm using a PIC.

Most important thing is this must power from batteries.

This is a hand held project so it must use batteries.To make the design compact I planned to use MOSFETS instead of BJTs.So I can eliminate base resisters as well.

hi,
Have a look at this dual.:)
 

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I planned to use MOSFETS instead of BJTs.So I can eliminate base resisters as well.
Then use 'digital' transistors which have a base resistor built-in.
 
Retails in the UK at £0.2, not bad for a dual, decent spec.
Well I have to admit that I neglected to check what price I was up against... I was more up at arms over the package really.

It is not easy to solder that pitch by hand when there are leads, never mind when there aren't. I am assuming he is trying to solder leads to it, as most here would not have PCBs for that kind of work.

Dan
 
Well I have to admit that I neglected to check what price I was up against... I was more up at arms over the package really.

It is not easy to solder that pitch by hand when there are leads, never mind when there aren't. I am assuming he is trying to solder leads to it, as most here would not have PCBs for that kind of work.

Dan

hi,
I bought some ADS1100 16 bit adc's recently, they are small!, I have a bench magnifier and they are still small.
The solder iron tip looks like a jack hammer.

The idea is to mount one piggy back on a 16F876, using Kynar to wire the legs to the SPI lines of the PIC, pick up the PIC power and 'share' an analog input.
Its going to be a rainy day job..:rolleyes:
 
hi,
I bought some ADS1100 16 bit adc's recently, they are small!, I have a bench magnifier and they are still small.
The solder iron tip looks like a jack hammer.

The idea is to mount one piggy back on a 16F876, using Kynar to wire the legs to the SPI lines of the PIC, pick up the PIC power and 'share' an analog input.
Its going to be a rainy day job..:rolleyes:
LOL how about an ADS8324? I use the SOT23 package that the ADS1100 is in all the time :)

Dan
 
I always use minimum and maximum spec's instead of a "typical" graph.
The graph for a "typical" 2N7000 Mosfet shows lots of output current when its input voltage is low. But the specs have a maximum theshold voltage of 3.0V when the current is only 1mA. It is spec'd to conduct well when its gate is 4.5V and 10V.

You don't know if you get a good one or or not so good one when buying a 2N7000 Mosfet.
 
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