Is a 12V Tri-state Buffer Available for Programming PIC Microcontrollers?

[Antonio Serrano]

Hello,

I'm trying to build a hub to connect several circuits that have a PIC microcontroller and be able to select one of them and download the program to it. The circuit that I have in mind to select and program one PIC microcontroller is this:

https://drive.google.com/file/d/0Bx4OvUVy2qxlUmpHcTVqc05STFU/view?usp=sharing

@PIC is the address in the bus of the PIC to program, select actually puts a different value than Hi-Z in the final output for the PIC selected with @PIC, and RS_/PG is to select if we want to program the PIC (the output must have the programming voltage) or to reset the PIC (0 in the output).

My problem is, the output (Vpp) high-level must be the programming voltage, that is Vdd + 4V minimum (I'm using Vdd=3.3V so Vpp must be minimum 7.3 and max 12.5). I want to output there 12V. The other day I was searching the internet for Tri-state buffers that could output 12V and I swear I found some, but now I've been searching for them for hours in the Internet and I don't find them any more.
Anyone knows if that component really exists (12V Tri-state buffer, for example four gates in one chip) or I dreamed about that? And in case there's not such a thing, how do you think guys that I could implement this circuit?

Thanks in advance!

 

[Svein]

Try this link: http://www.onsemi.com/pub_link/Collateral/MC14503B-D.PDF

 

[Antonio Serrano]

Thanks for the fast reply.
Unfortunately, this doesn't fit my application. I need a chip that offers DIP package. And also I intend to put 3.3V in the inputs of the tri-state buffers (either in the value input and in the contro input). In the MC14503B, if you want 12V in the output, I think you have to put at least 11.5 or so V in the input.
I've found a similar one, the MM54C941, but has the same problem, if I want output at high voltage, the input must be high voltage as well.
Thanks for the info.

 

[Baluncore]

I think you should consider open collector control rather than tristate.
Also consider a CD4049 or CD4050 as the driver. It has adjustable output voltage and logic level input.

 

[Svein]

CMOS level shifters exist. One example: http://www.ti.com/lit/ds/schs369/schs369.pdf. You can also do level shift with a transistor and a couple of resistors.