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
' x% c6 r) w8 y+ u) {0 Q% c8 f1 }: 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.....
! X# W& g2 M8 S我的想法正確嗎??

  J7 @/ E( j$ |' F8 @: Z如果布正確的話....
能麻煩各位幫我做個詳細的解說嗎??

先說聲謝謝~
6 H; G1 [/ w! _7 B


----------以下是DATASHEET針對VCCIO & VCCINT所做的說明------------

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
( N; |+ O! j1 Z* y- S, |systems that have differing supply voltages. The 5.0-V devices in all
8 c6 X8 m; V, Z" u/ P4 ?4 w! D9 y% fpackages can be set for 3.3-V or 5.0-V I/O pin operation. These devices
& e" C+ h4 J5 ], c1 }have one set of VCC pins for internal operation and input buffers
(VCCINT), and another set for I/O output drivers (VCCIO).
* [6 |7 A+ m9 Q" C/ [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.
+ X" j' ~  T3 P0 N$ s& }7 M4 CThe 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
$ g1 T) F8 _0 R. yconnected 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
, b/ p" A7 ?2 T' Y- v* {7 S3.3 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.

- G6 S$ D6 }& ^, z[ 本帖最後由 jimcooper 於 2008-11-9 04:21 PM 編輯 ]