54AC164245 and 5962R9858008VZC

[rpmiller]

Hi I'm using this device in a space design.  I just want to clarify the voltage requirements.  In all cases, I have Vdd1 >= Vdd2, as specified.  However, I'm using the device in these configurations and I want to confirm that the voltage levels are valid (it appears so from the datasheet but it's a little confusing):

Vdd1=5.0V, Vdd2=5.0V

Vdd1=3.3V, Vdd2=3.3V

Vdd1=5.0V, Vdd2=3.3V

Vdd1=5.0V, Vdd2=2.5V

Vdd1=3.3V, Vdd2=2.5V

Also, is there any requirement for the power connections for the 2 halves of the part.  For instance, I have one part with Vdd1-1=5.0V, Vdd2-1=3.3V  and Vdd1-2=3.3V, Vdd2-2=2.5V.

Thanks for your time,

Ryan Miller

Chief Engineer, Digital System

University of Michigan

Space Physics Research Laboratory

[Peter BENSCH]

Welcome @rpmiller, to the community!

Firstly, a note: the terms and conditions for the community indicate, among other things, that it is a place for mutual help between users. However, questions about Space applications are usually very specific, so they are better addressed to the Online Support OLS.

However, I will try to answer your questions:

• your planned voltage levels you mentioned are permissible according to the data sheet, as VDD1 is always equal to or greater than VDD2 (see data sheet, e.g. table 4, footnote 1)
• if I understand your question correctly, are you assuming that the two 8-bit ports have separate supply voltages?
  However, this is not the case, one 54AC164245 has only one VDD pin and one VSS pin. For the simultaneous conversion from 5V to 3.3V and 3.3V to 2.5V, you must use a separate 54AC164245 for each.

Does it answer your questions?

Regards
/Peter

[rpmiller]

Thank you for the timely response.  Regarding the VDD and VSS pins.  There are, in fact, 2 VDD1 pins and 2 VDD2 pins.  Just to clarify, the 2 VDD1 pins are connected together internally and the 2 VDD2 pins are connected together internally as well?  I think you are saying this is the case, which is not surprising, but I just want to confirm.

Thanks again,

Ryan Miller.

[Peter BENSCH]

Sorry, I had mixed something up here.

Yes, there are indeed two separate pins for VDD1, VDD2 and VSS, but I currently have no information that they are connected to each other. As previously mentioned, you should open a ticket in OLS for final confirmation.

The only information to be found in the data sheet is that both voltages VDD1 and VDD2 must be switched to 0 for cold spare use (section 1.1).

Regards
/Peter