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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我已經看我DATASHEET上對這方面的說明,但感覺還是有點不清楚
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.....
: ^& j9 S5 q" O" F& Z我的想法正確嗎??
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如果布正確的話....
5 D: v( P2 X) i7 ]7 T* L能麻煩各位幫我做個詳細的解說嗎??
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先說聲謝謝~
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0 y) K! v* j, J----------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
% Z0 b% N( l$ L6 B) a+ Y2 Hinterface feature, which allows MAX 7000 devices to interface with
" {/ b9 o4 p6 j& ^- Psystems that have differing supply voltages. The 5.0-V devices in all
7 W/ f. a: v. e0 a6 i% Npackages can be set for 3.3-V or 5.0-V I/O pin operation. These devices
) Z8 \2 h5 i5 j: @6 A3 chave one set of VCC pins for internal operation and input buffers
(VCCINT), and another set for I/O output drivers (VCCIO).
: j: z- u4 g, x' Q5 K3 B$ _The VCCINT pins must always be connected to a 5.0-V power supply.
% m5 i! v4 B, fWith a 5.0-V VCCINT level, input voltage thresholds are at TTL levels, and
4 f1 Y! v6 |1 L# v# s# sare 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
supply, depending on the output requirements. When the VCCIO pins are
1 f( a% w) X4 q2 u7 b. iconnected to a 5.0-V supply, the output levels are compatible with 5.0-V
systems. When VCCIO is connected to a 3.3-V supply, the output high is
5 Z# Q8 q8 j4 `5 T3.3 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
' j0 d, r, Z+ b( w2 ?timing delay of tOD2 instead of tOD1.

8 |; v3 C  L- T+ x) h# t[ 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
5 t: {; c8 {5 J0 EVCCINT接5v,則當io pin為輸入時,可接受3.3v,5v的輸入準位
8 K  V  m+ [7 |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
2 ?3 I& [4 ?6 w- m. b
[ 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!
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;
9 W4 o- o. t& S$ O9 Q& N  ]* z% W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!
參考參考!