初學者一問......有關EPM7128S......VCCINT & VCCIO的問題

jimcooper

請問一下VCCINT & VCCIO還有其對應的GND 這些腳位是做甚麼用的啊??

我已經看我DATASHEET上對這方面的說明,但感覺還是有點不清楚
4 h4 d' Y- P# n2 D  \感覺上VCCINT & VCCIO好像只需要各接一隻腳就可以了,其他相同名稱的腳位都是相通的.....
! Q% M9 `+ \2 Q: e8 k我的想法正確嗎??

如果布正確的話....
* q0 O& M2 m% i- J  [+ v# B& }能麻煩各位幫我做個詳細的解說嗎??
: L3 k4 ?8 B( H7 ~3 q8 R+ G; v
先說聲謝謝~
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! Q# _6 B- H" S: r' h/ O3 j5 w& C9 @
2 U% V* n, ?2 Z----------以下是DATASHEET針對VCCIO & VCCINT所做的說明------------

& l, ~" j  Y7 f5 a" u2 V4 ^MultiVolt I/O Interface

MAX 7000 devices—except 44-pin devices—support the MultiVolt I/O
interface feature, which allows MAX 7000 devices to interface with
6 v# C0 Y! Q0 m2 M3 S4 Ksystems that have differing supply voltages. The 5.0-V devices in all
packages can be set for 3.3-V or 5.0-V I/O pin operation. These devices
$ K! I5 \7 ?0 q% P- I/ f7 A4 nhave one set of VCC pins for internal operation and input buffers
+ B5 v* j3 ?6 c0 D(VCCINT), and another set for I/O output drivers (VCCIO).
The VCCINT pins must always be connected to a 5.0-V power supply.
With a 5.0-V VCCINT level, input voltage thresholds are at TTL levels, and
are therefore compatible with both 3.3-V and 5.0-V inputs.
1 t! C# L( g. x) t( f- C2 Y3 [The VCCIO pins can be connected to either a 3.3-V or a 5.0-V power
8 B4 U! |1 X: Zsupply, depending on the output requirements. When the VCCIO pins are
connected to a 5.0-V supply, the output levels are compatible with 5.0-V
  s8 P: O9 U; Q- M, H( E& T8 lsystems. When VCCIO is connected to a 3.3-V supply, the output high is
3.3 V and is therefore compatible with 3.3-V or 5.0-V systems. Devices
* R) b! i: d* q# D3 L5 J1 B5 qoperating with VCCIO levels lower than 4.75 V incur a nominally greater
timing delay of tOD2 instead of tOD1.

+ J. N  R# G: b0 g! y. l  {3 x3 m[ 本帖最後由 jimcooper 於 2008-11-9 04:21 PM 編輯 ]

sieg70

Vccint跟Vccio, 以及Ground"每根"都要接

addn

您好
0 ~& u6 s9 u+ }. d1 LVCCINT接5v,則當io pin為輸入時,可接受3.3v,5v的輸入準位
% m0 N$ w$ S$ @, v) E7 aVCCIO接5v/3.3v,則當io pin為輸出時,輸出準位就為5v/3.3v準為位

0 Q# p/ W5 x) r* w4 m[ 本帖最後由 addn 於 2008-11-10 10:16 AM 編輯 ]

ssejack1

VCCIO 在有些產品有分 block, 當不同 IO 電壓要使用在同一顆 IC 時可以劃分在不同的 block 就可同時使用不同之IO 準位; VCCINT 為 IC core 電壓,與 user 較沒直接關係,只要依 spec. 供給就沒有問題!
0 c8 x9 n% T+ Q+ m4 ]* l須注意的是 VCCINT 與 VCCIO 有點影響,越低的 VCCINT 製程越新, delay / speed 多比較快,壞處是 VCCIO 會較低;
比如 VCCINT = 3.3V者, VCCIO 一般 3.3/5.0 均可,但 VCCINT = 2.5者 VCCIO 或許無法始用 5.0 v 了!
1 R9 {$ M5 c  A8 B參考參考!