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??
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' Q) i2 N7 i+ C! u- I2 v我已經看我DATASHEET上對這方面的說明,但感覺還是有點不清楚
" c6 C& t. B& f  U- {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.....
1 A: x. J  Z! y我的想法正確嗎??

( |" R) I# _7 F0 D: M' h* Q如果布正確的話....
( o3 U, M; u) h3 v能麻煩各位幫我做個詳細的解說嗎??
6 o4 s% L: N% P6 Y7 g
先說聲謝謝~


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: n$ P3 V- \  b3 n8 {----------以下是DATASHEET針對VCCIO & VCCINT所做的說明------------
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MultiVolt I/O Interface
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MAX 7000 devices—except 44-pin devices—support the MultiVolt I/O
9 K3 h: I0 F' I/ U; [interface feature, which allows MAX 7000 devices to interface with
systems that have differing supply voltages. The 5.0-V devices in all
3 C* U$ P# \8 Tpackages can be set for 3.3-V or 5.0-V I/O pin operation. These devices
4 u- a9 \* j% J) [% z7 {have one set of VCC pins for internal operation and input buffers
# ~0 d8 x4 _$ v  i; p! W(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
0 q6 b' ?7 @% F7 ^( {are therefore compatible with both 3.3-V and 5.0-V inputs.
The VCCIO pins can be connected to either a 3.3-V or a 5.0-V power
$ S' Z7 k2 _! r6 U8 ^! msupply, 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
+ [! B# z3 c6 @systems. 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
1 y' N5 R% b: y; zoperating with VCCIO levels lower than 4.75 V incur a nominally greater
timing delay of tOD2 instead of tOD1.

[ 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
  e8 H* f$ k! ]9 w3 |+ Q) T4 qVCCINT接5v,則當io pin為輸入時,可接受3.3v,5v的輸入準位
VCCIO接5v/3.3v,則當io pin為輸出時,輸出準位就為5v/3.3v準為位
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[ 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!
, q' Z; y  @- k4 V8 Y% g: n& r& s2 e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;
3 l' S  W3 K2 C. l; T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!
! Y# |7 {  B0 q' U5 q參考參考!