User`s manual

User’s Manual 67

A.4 I/O Buffer Sourcing and Sinking Limit

Unless otherwise specified, the Rabbit I/O buffers are capable of sourcing and sinking 8 mA of cur-

rent per pin at full AC switching speed. Full AC switching assumes a 22.1 MHz CPU clock and

capacitive loading on address and data lines of less than 100 pF per pin. Pins A0–A12 and D0–D7

are each rated at 8 mA. The absolute maximum operating voltage on all I/O is V

+ 0.5 V, or 5.5 V.

Table A-5 shows the AC and DC output drive limits of the parallel I/O buffers when the Rabbit 2000

is used in the RCM2100.

Table A-5. I/O Buffer Sourcing and Sinking Capability

Pin Name

Output Drive

Sourcing

/Sinking

†

Limits

(mA)

* The maximum DC sourcing current for I/O buffers between V

pins is 112 mA.

† The maximum DC sinking current for I/O buffers between V

pins is 150 mA.

Output Port Name

Full AC Switching

SRC/SNK

Maximum

‡

DC Output

Drive

SRC/SNK

‡ The maximum DC output drive on I/O buffers must be adjusted to

take into consideration the current demands made my AC switch-

ing outputs, capacitive loading on switching outputs, and switching

voltage.

The current drawn by all switching and nonswitching I/O must

not exceed the limits specified in the first two footnotes.

PA [7:0] 8/8 12/12

PB [7, 1, 0] 8/8 12/12

PC [6, 4, 2, 0] 8/8 12/12

PD [7:4] 8/8 12/12

PD [3:0]

** The combined sourcing from Port D [7:0] may need to be adjusted

so as not to exceed the 112 mA sourcing limit requirement speci-

fied in the first footnote.

16/16 25/25

PE [7:0] 8/8 12/12