Bus Loading - Rabbit RCM3000 User Manual

A.2 Bus Loading
You must pay careful attention to bus loading when designing an interface to the
RCM3000. This section provides bus loading information for external devices.
Table A-2 lists the capacitance for the various RCM3000 I/O ports.
Table A-3 lists the external capacitive bus loading for the various RCM3000 output ports.
Be sure to add the loads for the devices you are using in your custom system and verify
that they do not exceed the values in Table A-3.
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Table A-2. Capacitance of Rabbit 3000 I/O Ports
I/O Ports
Parallel Ports A to G
Table A-3. External Capacitive Bus Loading -40°C to +70°C
Clock Speed
Output Port
All I/O lines with clock
doubler enabled
All I/O lines with clock
doubler disabled
Input
Capacitance Capacitance
(pF)
12
Maximum External
(MHz) Capacitive Loading (pF)
29.4 30–70
14.7456 100
Output
(pF)
14
RabbitCore RCM3000