PEEL22LV10AZTI-25 ETC2 [List of Unclassifed Manufacturers], PEEL22LV10AZTI-25 Datasheet - Page 4

• Manufacturer Part Number: PEEL22LV10AZTI-25
• Description: CMOS Programmable Electrically Erasable Logic Device
• Manufacturer: ETC2 [List of Unclassifed Manufacturers]

Programmable I/O Macrocell
The unique twelve-configuration output macrocell
provides complete control over the architecture of each
output.
independently lets you to tailor the configuration of the
PEEL22LV10AZ to the precise requirements of your
design.
Macrocell Architecture
Each I/O macrocell, as shown in Figure 4, consists of a
D-type flip-flop and two signal-select multiplexers. The
configuration of each macrocell is determined by the
four EEPROM bits controlling these multiplexers. These
bits determine output polarity, output type (registered or
non-registered) and input-feedback path (bidirectional
I/O, combinatorial feedback). Refer to Table 1 for
details.
Equivalent
configurations are illustrated in Figure 6. In addition to
emulating
(configurations 3, 4, 9, and 10), the macrocell provides
eight additional configurations. When creating a PEEL
device design, the desired macrocell configuration is
generally specified explicitly in the design file. When the
design is assembled or compiled, the macrocell
configuration bits are defined in the last lines of the
JEDEC programming file.
Output Type
The signal from the OR array can be fed directly to the
output pin (combinatorial function) or latched in the D-
type flip-flop (registered function). The D-type flip-flop
latches data on the rising edge of the clock and is
controlled by the global preset and clear terms. When
the synchronous preset term is satisfied, the Q output of
the register is set HIGH at the next rising edge of the
clock input. Satisfying the asynchronous clear sets Q
LOW, regardless of the clock state. If both terms are
satisfied simultaneously, the clear will override the
preset.
Output Polarity
Each macrocell can be configured to implement active-
high
eliminates the need for external inverters.
Output Enable
The output of each I/O macrocell can be enabled or
disabled
programmable output enable product term. When the
logical conditions programmed on the output enable
term are satisfied, the output signal is propagated to the
I/O pin. Otherwise, the output buffer is switched into the
high-impedance state.
Under the control of the output enable term, the I/O pin
can function as a dedicated input, a dedicated output,
or
The
active-low
under
the
circuits
ability
four
the
logic.
for
PAL-type
to
control
configure
the
Programmable
of
twelve
output
its
each
associated
structures
macrocell
polarity
output
4
or a bi-directional I/O. Opening every connection on the
output 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.
Input/Feedback Select
The PEEL22LV10AZ macrocell also provides control
over the feedback path. The input/feedback signal
associated with each I/O macrocell can be obtained
from three different locations; from the I/O input pin,
from the Q output of the flip-flop (registered feedback),
or directly from the OR gate (combinatorial feedback).
Bi-directional I/O
The input/feedback signal is taken from the I/O pin
when using the pin as a dedicated input or as a bi-
directional I/O. (Note that it is possible to create a
registered output function with a bi-directional I/O, refer
to Figure 4.
Figure 4 - Block Diagram of the PEEL22LV10AZ I/O
Macrocell
Combinatorial Feedback
The signal-select multiplexer gives the macrocell the
ability to feedback the output of the OR gate, bypassing
the output buffer, regardless of whether the output
function is registered or combinatorial. This feature
allows the creation of asynchronous latches, even when
the output must be disabled. (Refer to configurations 5,
6, 7, and 8 in Figure 6.)
Registered Feedback
Feedback also can be taken from the register,
regardless
programmed to be combinatorial or registered. When
implementing
registered feedback allows for the internal latching of
states without giving up the use of the external output.
of
a
whether
combinatorial
the
PEEL
output
output
TM
22LV10AZ
function
04-02-037D
function,
is