User`s manual

User’s Manual 45
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 current 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.
Address pin A0 and data pin D0 are rated at 16 mA each. Pins A1–A4 and D1–D7 are
each rated at 8 mA. The absolute maximum operating voltage on all I/O is V
DD
+ 0.5 V, or
5.5 V.
Table A-6 shows the AC and DC output drive limits of the parallel I/O buffers when the
Rabbit 2000 is used in the RCM2300.
Table A-6. 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
DD
pins is 112 mA.
† The maximum DC sinking current for I/O buffers between V
SS
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
switching 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, 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 require-
ment specified in the first footnote.
16/16 25/25
PE [7:0] 8/8 12/12