that features ultra-low, automatic “zero” power-down operation.
The “zero power” (100 µA max. Icc) power-down mode makes the
PEEL™18CV8Z ideal for a broad range of battery-powered
portable equipment applications, from hand-held meters to PCM-
CIA modems. EE-reprogrammability provides both the conve-
nience of fast reprogramming for product development and quick
product personalization in manufacturing, including Engineering
Change Orders.
The PEEL™18CV8Z is logically and functionally similar to
Anachip’s 5 Volt PEEL™18CV8 and 3 Volt PEEL™18LV8Z.
The
differences
between
the
PEEL™18CV8Z
and
PEEL™18CV8 include the addition of programmable clock
polarity, a product term clock, and variable width product terms in
the AND/OR Logic Array.
Like the PEEL™18CV8, the PEEL™18CV8Z is logical superset
of the industry standard PAL16V8 SPLD. The PEEL™18CV8Z
provides additional architectural features that allow more logic to
be incorporated into the design. Anachip’s JEDEC file translator
allows easy conversion of existing 20 pin PLD designs to the
PEEL™18CV8Z architecture without the need for redesign. The
PEEL™18CV8Z architecture allows it to replace over twenty
standard 20-pin DIP, SOIC, TSSOP and PLCC packages.
Figure 7 Pin Configuration
I/CLK
I
I
I
I
I
I
I
I
GND
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
VCC
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
Figure 8 Block Diagram
CLK MUX (Optional)
DIP
TSSOP
™
PLCC
SOIC
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under
any patent accompany the sale of the product.
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effect on the output function).
Function Description
The PEEL™18CV8Z implements logic functions as sum-of-
products expressions in a programmable-AND/fixed-OR logic
array. User-defined functions are created by programming the
connections of input signals into the array. User-configurable
output structures in the form of I/O macrocells further increase
logic flexibility.
Variable Product Term Distribution
The PEEL™18CV8Z provides 113 product terms to drive the
eight OR functions. These product terms are distributed among the
outputs in groups of 8, 10, 12, 14, and 16 to form logical sums
(see Figure 9). This distribution allows optimum use of the
device resources.
Architecture Overview
The PEEL™18CV8Z architecture is illustrated in the block dia-
gram of Figure 8. Ten dedicated inputs and 8 I/Os provide up to
18 inputs and 8 outputs for creation of logic functions. At the core
of the device is a programmable electrically-erasable AND array
that drives a fixed OR array. With this structure, the
PEEL™18CV8Z can implement up to eight sum-of-products
logic expressions.
Associated with each of the eight OR functions is an I/O macro-
cell that can be independently programmed to one of 12 different
configurations. The programmable macrocells allow each I/O to be
used to create sequential or combinatorial logic functions of
active-high or active-low polarity, while providing three different
feedback paths into the AND array.
Programmable I/O Macrocell
The unique twelve-configuration output macrocell provides com-
plete control over the architecture of each output. The ability to
configure each output independently lets you to tailor the config-
uration of the PEEL™18CV8Z to the precise requirements of
your design.
Macrocell Architecture
Each I/O macrocell, as shown in Figure 9, consists of a D-type
flip-flop and two signal-select multiplexers. The configuration of
each macrocell is determined by the four EEPROM bits control-
ling these multiplexers. These bits determine output polarity, out-
put type (registered or non-registered) and input-feedback path
(bidirectional I/O, combinatorial feedback). Refer to Table 1 for
details.
Equivalent circuits for the twelve macrocell configurations are
illustrated in Figure 11. In addition to emulating the four PAL-
type output structures (configurations 3, 4, 9, and 10), the macro-
cell 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.
AND/OR Logic Array
The programmable AND array of the PEEL™18CV8Z (shown in
Figure 9) is formed by input lines intersecting product terms. The
input lines and product terms are used as follows:
36 Input Lines:
– 20 input lines carry the true and complement of the signals
applied to the 10 input pins
– 16 additional lines carry the true and complement values of
feedback or input signals from the 8 I/Os
113 product terms:
– 102 product terms are used to form sum of product functions
– 8 output enable terms (one for each I/O)
– 1 global synchronous preset term
– 1 global asynchronous clear term
– 1 programmable clock term
At each input-line/product-term intersection, there is an
EEPROM memory cell that determines whether or not there is a
logical connection at that intersection. Each product term is
essentially a 36-input AND gate. A product term that is con-
nected to both the true and complement of an input signal will
always be FALSE and thus will not affect the OR function that it
drives. When all the connections on a product term are opened, a
“don’t care” state exists and that term will always be TRUE. When
programming the PEEL™18CV8Z, the device program- mer first
performs a bulk erase to remove the previous pattern. The erase
cycle opens every logical connection in the array. The device is
configured to perform the user-defined function by pro- gramming
selected connections in the AND array. (Note that PEEL™
device programmers automatically program all of the connections
on unused product terms so that they will have no
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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 (regis-
tered 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 out-
put 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 or
active-low logic. Programmable polarity eliminates the need for
external inverters.
Output Enable
The output of each I/O macrocell can be enabled or disabled
under the control of its associated programmable output enable
product term. When the logical conditions programmed on the
output enable term are satisfied, the output signal is propagated to
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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 func-
tion as a dedicated input, a dedicated output, or a bi-directional I/ O.
Opening every connection on the output enable term will per-
manently 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.
tion, registered feedback allows for the internal latching of states
without giving up the use of the external output.
Programmable Clock Options
A unique feature of the PEEL™18CV8Z is a programmable
clock multiplexer that allows the user to select true or comple-
ment forms of either input pin or product-term clock sources.
Zero Power Feature
The CMOS PEEL™18CV8Z features “Zero-Power” standby
operation for ultra-low power consumption. With the “Zero-
Power” feature, transition-detection circuitry monitors the inputs,
I/Os (including CLK) and feedbacks. If these signals do not
change for a period of time greater than approximately two t
PD
’s,
the outputs are latched in their current state and the device auto-
matically powers down. When the next signal transition is
detected, the device will “wake up” for active operation until the
signals stop switching long enough to trigger the next power-
down. (Note that the tPD is approximately 5 ns. slower on the first
transition from sleep mode.)
As a result of the “Zero-Power” feature, significant power sav-
ings can be realized for combinatorial or sequential operations
when the inputs or clock change at a modest rate. See Figure 5.
Input/Feedback Select
The PEEL™18CV8Z 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 feed-
back).
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-direc-
tional I/O, refer to Figure 9).
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 combi-
natorial. 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 11.)
Figure 10 Typical ICC vs. Input Clock Frequency
for the 18CV8Z
100
10
Figure 9 Block Diagram of the PEEL™18CV8Z
I/O Macrocell
Registered Feedback
Feedback also can be taken from the register, regardless of
whether the output function is programmed to be combinatorial
or registered. When implementing a combinatorial output func-
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