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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7 I5 n* E# _4 @9 }$ u7 C. A4 ~我已經看我DATASHEET上對這方面的說明,但感覺還是有點不清楚
* R- S% ]: U8 W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.....
我的想法正確嗎??
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1 G5 R, V( z" j如果布正確的話....
能麻煩各位幫我做個詳細的解說嗎??

3 W9 M3 Q, y5 Q2 ^, e+ U$ B先說聲謝謝~
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4 f/ Q" y4 D& T/ V----------以下是DATASHEET針對VCCIO & VCCINT所做的說明------------
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MultiVolt I/O Interface

MAX 7000 devices—except 44-pin devices—support the MultiVolt I/O
( [- Z8 L$ d: I) |interface feature, which allows MAX 7000 devices to interface with
systems that have differing supply voltages. The 5.0-V devices in all
  M8 j: @1 H$ h4 N8 X" Apackages can be set for 3.3-V or 5.0-V I/O pin operation. These devices
; S/ H/ U* V6 ~1 X5 [5 ~have one set of VCC pins for internal operation and input buffers
(VCCINT), and another set for I/O output drivers (VCCIO).
& y' J" T+ h$ x" fThe VCCINT pins must always be connected to a 5.0-V power supply.
! E; k8 s9 s9 ^9 K0 ^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.
+ v0 w) v  k  L/ k! ]The VCCIO pins can be connected to either a 3.3-V or a 5.0-V power
$ b) p- A& a; F- osupply, depending on the output requirements. When the VCCIO pins are
: J# r' C& X' L, @( ~  kconnected to a 5.0-V supply, the output levels are compatible with 5.0-V
5 u1 N  J5 {" \systems. When VCCIO is connected to a 3.3-V supply, the output high is
4 D5 ~" U4 j& c, L, k0 K3.3 V and is therefore compatible with 3.3-V or 5.0-V systems. Devices
operating with VCCIO levels lower than 4.75 V incur a nominally greater
timing delay of tOD2 instead of tOD1.
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' \' c6 T+ Y' j. q[ 本帖最後由 jimcooper 於 2008-11-9 04:21 PM 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!
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;
' P! ?: ]8 a! a: u: y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!
0 ~: [2 M4 i1 ]- F參考參考!

addn

您好
VCCINT接5v,則當io pin為輸入時,可接受3.3v,5v的輸入準位
# Y. a+ Z2 l- }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

! }. C! F+ Z& ]$ D- p+ ^. B[ 本帖最後由 addn 於 2008-11-10 10:16 AM 編輯 ]

sieg70

Vccint跟Vccio, 以及Ground"每根"都要接