|Re: PPC MLDL Project|
Message #4 Posted by Donald Leonard on 8 June 2003, 4:21 a.m.,
in response to message #1 by Jeff
Now that you have given specific information regarding your problem with the PPC MLDL design, I'll try to give you some suggestions.
First, the comment about CMOS inputs being tied to ground or supply - that is correct, as is the comment that I.C.'s with floating inputs can draw EXCESSIVE current. In fact, ground is the preferred referance/connection in most designs. And my understanding of the port connections is that (looking INTO the calculator port, out of the MLDL plug, or INTO the BACK of the plug) Vbat is the first connection on the left, followed by B4, Vcc, B3, GND, PWO, DATA, FI, ISA, SYNC, 02, 01. Vbat is the battery voltage (RAM sustain voltage) and Vcc is a higher voltage generated by a power converter inside the calculator which powers the active/operational circuits when the calculator is turned on. They are not the same. Don