ソリューション ID: rd12082003_9642
掲載日: 2010年6月18日
製品カテゴリー: デバイス
製品エリア: I/O(デバイス)
製品サブ・エリア: I/O 構造/機能
デバイス・ファミリ: MAX 3000A

件名

What is the status of the I/O pins on an un-programmed MAX® 3000A, 7000S, 7000A, 7000B, and MAX II device?

回答

All MAX3000A, 7000S, 7000A, 7000B, and MAX II devices are shipped blank from the factory. When a blank device is powered up, all of the I/O pins are tri-stated.

If you erase a MAX 3000A, 7000A, 7000B, or MAX II device it behaves the same as a blank new factory shipped device. The I/O pins of a blank device are tri-stated when powered.

However, this is not true for MAX 7000S. A new MAX 7000S device shipped from factory will tri-state when powered, but if this device is erased in some manner (Jam, JBC, SVF, etc), then the I/O pins will drive out undetermined values. This is because a new MAX 7000S part shipped from the factory is blank except for some OE control bits which are set to tri-state the I/O pins. When erased, those OE bits are cleared and the I/O pins drive out. In order to tri-state the I/O pins again, you need to examine and save a .pof from a blank new MAX 7000S device shipped from the factory. Program the affected MAX 7000S with the saved .pof so that it will behave the same as a blank new device shipped from the factory again, with all the I/Os tri-stated.

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