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[讨论] 用过QUALCOMM平台的请进!

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发表于 2006-5-23 18:16:00 | 显示全部楼层 |阅读模式
在QUALCOMM 的基带DATASHEET中,PAD TAYE 是 KEEPER。
对于KEEPER,QUALCOMM说明如下:
These keepers are weak flip-flops (easily over-driven by an external source) on the pad-side of the structure to encourage an otherwise-undriven pad voltage to migrate to a power or ground rail, either to help ensure hold-time requirements or to minimize power consumption within otherwise undriven pad
structures. Keepers have the following impacts on the physical interface:
■ External sources driving these pins must overcome the keepers in order to drive a logic level
on such pins. The amount of current required must be greater than the maximum IOZLKP value
in Table 3-4 and Table 3-5.
■ At the point when an external source releases control of such pins, the keepers tend to hold the
last logic level on the pins (subject to system-level leakages and capacitive loading effects).
The minimum IOZLKP current values may be sustained indefinitely without upsetting the state of the keeper.
对上面这段具体怎么理解?
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