| [ KAIST ] in KIDS 글 쓴 이(By): concerto (#20) 날 짜 (Date): 2001년 11월 27일 화요일 오전 12시 41분 05초 제 목(Title): Re: [q] 디지털 하드웨어 도사님들께... 낄낄,, technical support를 미리 이용할 껄... :) ==question== Hello, I'm using external data(asserted by PLD) lines to configure initial states during reset. The data lines may be conncected to a data tranceiver(74ALB16245, ti, bicmos, not include a hold-circuit). If the data trncvr is not assembled, it operates perfectly. But assembled, there is trouble. I think it may come from xxx's the weak pull-down and trncvr's schottky diode or something like that. So, I'm planning to substitute the trncvr with CMOS-type one. If there is comments on my case, please inform me. And, please check my consideration. Thank you in advance. ==answer== You are right, xxx's internal pull downs are very weak. So any input connected to the data bus with great input current can distort logic level during configuration. I checked 74ALB16245 specification, it really has very great input current. Use tranceivers with maximum input leakage current less than 5-10uA. The less the better. Yesterday is History, Tomorrow is a Mystery, and Today is a gift; that's why we call it - the Present... |