Author Topic: Multiple NMOS in same package  (Read 2065 times)

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Offline lmagalhaesTopic starter

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Multiple NMOS in same package
« on: April 03, 2020, 04:48:44 pm »
Hi there,

Does anyone have a PN for multiple (preferably 8) NMOS in the same SMD package? Do NPN darlington transistors do the same job ? I'm just looking for a ground connection to be turned on and off.

Thanks !
 

Offline TheHolyHorse

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Re: Multiple NMOS in same package
« Reply #1 on: April 03, 2020, 04:58:20 pm »
A darlington pair wont give you individual control of each BJT. But what's the reason for wanting them all in the same package?
 

Offline TheHolyHorse

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Re: Multiple NMOS in same package
« Reply #2 on: April 03, 2020, 05:02:33 pm »
If you want a package with multiple fets in one, just go on mouser or whatever and in the parametric search select the number of channels you want.

https://www.mouser.se/Semiconductors/Discrete-Semiconductors/Transistors/MOSFET/_/N-ax1sf?P=1z0z7ptZ1yzxao2Z1yzxao0Z1yzvta6Z1yzvta3Z1yx7p9yZ1z0y3zr
 

Offline Alti

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Re: Multiple NMOS in same package
« Reply #3 on: April 03, 2020, 06:19:10 pm »
Well, I do not know what you need.
Of course any CMOS chip is full of mos transistors in one package. I can recommend you 74HC595 which has 8 ios driven high or low, through SPI. There are also parallel driven versions, with HZ, without, whatnot.
If you want higher currents and n-mos then look for LED drivers. Usually come in the package of 8 or 16. From 20mA up to 90mA per channel. Serial in.
Then there is ULN2003/4 which is bipolar npnp (darlington).
And various BC856 type pairs.


 

Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #4 on: April 03, 2020, 09:46:20 pm »
I'm trying to control electrochromic displays and for that I need to connect the counter-electrode to 1.5V and each electrode to ground. Right now, the board has 8 channels to control 8 displays in parallel and each display may have up to 8 electrodes. This means that if I use discrete NMOS for each electrode (IRLML6344 is what I'm using right now) I'm going to have 64 discrete MOSFETs... that's a whole lot of mosfets. But, if there were packages of 8, it would make my job easier when it gets to the part where I have to solder them all manually.
 

Offline up8051

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Re: Multiple NMOS in same package
« Reply #5 on: April 03, 2020, 10:01:19 pm »
 

Offline Alti

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Re: Multiple NMOS in same package
« Reply #6 on: April 03, 2020, 10:07:43 pm »
I'm trying to control electrochromic displays (..)(IRLML6344 is what I'm using right now)
That is a 5A NMOS. Pulse 25A.
What is the highest Rds_on that is acceptable in your design?


 

Offline T3sl4co1l

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Re: Multiple NMOS in same package
« Reply #7 on: April 03, 2020, 11:02:03 pm »
If it's low current, why not a logic device?  Does it have to be open drain?  (Buffers are available in either configuration, fortunately.)

Tim
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Offline senso

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Re: Multiple NMOS in same package
« Reply #8 on: April 03, 2020, 11:24:38 pm »
Maybe TPIC6B from TI?
 

Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #9 on: April 16, 2020, 01:44:29 pm »
Thanks for the suggestions.

The TPL7407LA is the closest one to what I need. I just need a switch to ground with the lowest possible Rdson since we need to measure the current consumption. The less series resistance the better.

However, the TPL7407 has a diode from the output to COM and that's not good ... I need a package without it. I've been looking in Mouser, but all of them have this, since this is to use with high power loads.

Shift registers will impose a limit to how much current they can sink, which might affect the readings and that's not good and it's really necessary to have a completly open circuit at the output.

Are there other circuits available ?

Thanks,

Luís
 

Offline T3sl4co1l

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Re: Multiple NMOS in same package
« Reply #10 on: April 16, 2020, 06:14:02 pm »
What's wrong with the diode?

Tim
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Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #11 on: April 16, 2020, 09:33:52 pm »
The diode is going to make the display bleach because it leaves a current path.
 

Offline T3sl4co1l

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Re: Multiple NMOS in same package
« Reply #12 on: April 17, 2020, 03:36:45 am »
Well, all your transistors have leakage paths too, so you're screwed..?!

How much leakage is tolerable?  How about pullups to bias the pin to +V or whatever?

Tim
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Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #13 on: April 17, 2020, 09:10:37 am »
The displays work like a capacitor, so they can't have a current path available. The mosfets do have leaks, but they keep the display in open circuit just fine. However a diode across the pins drains the display almost immediately.
 

Offline T3sl4co1l

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Re: Multiple NMOS in same package
« Reply #14 on: April 17, 2020, 01:38:25 pm »
So, it's like an LCD?  Wouldn't you want half bridge logic pins then?

Tim
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Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #15 on: April 17, 2020, 04:09:23 pm »
It's not really similar to LCD. In this case, I just want to color it and then leave it floating to measure the voltage level across the electrodes to check if there's a short.
 

Offline thinkfat

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Re: Multiple NMOS in same package
« Reply #16 on: April 18, 2020, 08:22:37 am »
TBD62783 ?
Everybody likes gadgets. Until they try to make them.
 

Offline lmagalhaesTopic starter

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Re: Multiple NMOS in same package
« Reply #17 on: April 21, 2020, 11:53:23 am »
The TBD62783 also has a diode on the output, so I can't use it.

Thank you all for the answers but I'm just going to use 4x NTJD5121NT1G. Too bad that I couldn't find anything like this but with more MOSFETs =\
 


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