| 摘要 |
A power detection and control unit detects the acceptable power voltage requirements of a removable system resource and either provides the acceptable power voltage to the removable system resource or provides no voltage to the removable system resource if no acceptable power voltage is available. The power detection and control unit has a detection circuitry and a logic circuitry to translate the acceptable power requirement signal into control signals that control the system power supply. In a first embodiment the detection circuitry consists of an A/D converter analog to digital converter, a resistor coupled to a predetermined power supply voltage, a resistor in the removable system resource coupled to ground, and a filtering capacitor coupled to ground. In a second embodiment, the detection circuitry includes a pattern imprinted on the casing of the removable system resource, a wiper circuit for applying onto the pattern and detecting from the pattern a power requirement signal. This power requirement signal is then translated into system power supply control signals as in the first embodiment.
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