enable term will permanently enable the output buffer and
yield a dedicated output. Conversely, if every connection is
intact, the enable term will always be logically false and the
I/O will function as a dedicated input.
Design Security
The PEEL™22CV10A provides a special EEPROM secu-
rity bit that prevents unauthorized reading or copying of
designs programmed into the device. The security bit is set
by the PLD programmer, either at the conclusion of the pro-
gramming cycle or as a separate step after the device has
been programmed. Once the security bit is set, it is impos-
sible to verify (read) or program the PEEL™ until the entire
device has first been erased with the bulk-erase function.
Input/Feedback Select
When configuring an I/O macrocell to implement a regis-
tered function (configurations 1 and 2 in Figure 5), the Q
output of the flip-flop drives the feedback term. When con-
figuring an I/O macrocell to implement a combinatorial
function (configurations 3 and 4 in Figure 5), the feedback
signal is taken from the I/O pin. In this case, the pin can be
used as a dedicated input or a bi-directional I/O. (Refer also
to Table 1.)
Signature Word
The signature word feature allows a 24-bit code to be pro-
grammed
into
the
PEEL™22CV10A
if
the
PEEL™22CV10A+ software option is used. Also, the sig-
nature word feature allows a 64-bit code to be programmed
into the PEEL™22CV10A if the PEEL™22CV10A++ soft-
ware option is used. The code can be read back even after
the security bit has been set. The signature word can be
used to identify the pattern programmed into the device or to
record the design revision, etc.
Additional Macro Cell Configurations
Besides the standard four-configuration macrocell shown in
Figure 5, each PEEL™22CV10A provides an additional
eight configurations that can be used to increase design
flexibility. The configurations are the same as provided by the
PEEL™18CV8 and PEEL™22CV10AZ. However, to
maintain JEDEC file compatibility with standard 22V10
PLDs the additional configurations can only be utilized by
specifying the PEEL™22CV10A+ and PEEL22CV10A++ for
logic assembly and programming. To reference these
additional configurations please refer to the specifications at
the end of this data sheet.
Figure 4. Block Diagram of the PEEL™ 22CV10A I/O Macrocell.
Anachip Corp.
www.anachip.com.tw
Rev. 1.0 Dec 16, 2004
4/10
ANACHIP [ ANACHIP CORP ]
