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58 RabbitCore RCM3000
A.4 I/O Buffer Sourcing and Sinking Limit
Unless otherwise specified, the Rabbit 3000 I/O buffers are capable of sourcing and sink-
ing 6.8 mA of current per pin at full AC switching speed. Full AC switching assumes a
29.4 MHz CPU clock and capacitive loading on address and data lines of less than 70 pF
per pin. The maximum Vcc is 3.6 V, and the absolute maximum operating voltage on all
parallel I/O is 5.5 V.
Table A-6 shows the AC and DC output drive limits of the parallel I/O buffers when the
Rabbit 3000 is used in the RCM3000.
Under certain conditions, the maximum instantaneous AC/DC sourcing or sinking current
may be greater than the limits outlined in Table A-6. The maximum AC/DC sourcing cur-
rent can be as high as 12.5 mA per buffer as long as the number of sourcing buffers does
not exceed three per V
DD
or V
SS
pad, or up to six outputs between pads. Similarly, the
maximum AC/DC sinking current can be as high as 8.5 mA per buffer as long as the num-
ber of sinking buffers does not exceed three per V
DD
or V
SS
pad, or up to six outputs
between pads. The V
DD
bus can handle up to 35 mA, and the V
SS
bus can handle up to
28 mA. All these analyses were measured at 100°C.
Table A-6. I/O Buffer Sourcing and Sinking Capability
Pin Name
Output Drive (Full AC Switching)
Sourcing/Sinking Limits
(mA)
Sourcing Sinking
All data, address, and I/O
lines with clock doubler
enabled
6.8 6.8
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