Commercial/Industrial
PEEL™ 18LV8Z-25 / I-35
CMOS Programmable Electrically Erasable Logic Device
Features
•
Low Voltage, Ultra Low Power Operation
- Vcc = 2.7 to 3.6 V
- Icc = 5 µA (typical) at standby
- Icc = 1.5 mA (typical) at 1 MHz
- Meets JEDEC LV Interface Spec (JEDSD8-A)
- 5 Volts tolerant inputs and I/O’s
CMOS Electrically Erasable Technology
- Superior factory testing
- Reprogrammable in plastic package
- Reduces retrofit and development costs
Application Versatility
- Replaces random logic
- Super set of standard PLDs
- Pin-to-pin compatible with 16V8
- Ideal for battery powered systems
- Replaces expensive oscillators
•
•
Architectural Flexibility
- Enhanced architecture fits in more logic
- 113 product terms x 36 input AND array
- 10 inputs and 8 I/O pins
- 12 possible macrocell configurations
- Asynchronous clear, Synchronous preset
- Independent output enables
- Programmable clock; pin 1 or p-term
- Programmable clock polarity
- 20 Pin DIP/SOIC/TSSOP and PLCC
- Schmitt triggers on clock and data inputs
Schmitt Trigger Inputs
- Eliminates external Schmitt trigger devices
- Ideal for encoder designs
•
•
General Description
The PEEL18LV8Z is a Programmable Electrically Erasable
Logic (PEEL) SPLD (Simple Programmable Logic Device)
that operates over the supply voltage range of 2.7V-3.6V
and features ultra-low, automatic "zero" power-down
operation. The PEEL18LV8Z is logically and functionally
similar to ICT's 5V PEEL18CV8 and PEEL18CV8Z. The
"zero power" (25
µA
max. Icc) power-down mode makes
the PEEL18LV8Z ideal for a broad range of battery-
powered portable equipment applications, from hand-held
meters to PCMCIA modems. EE-reprogrammability
provides both the convenience of fast reprogramming for
product development and quick product personalization in
manufacturing, including Engineering Change Orders.
The differences between the PEEL18LV8Z and
PEEL18CV8 include the addition of programmable clock
polarity, p-term clock, and Schmitt trigger input buffers on
all inputs, including the clock. Schmitt trigger inputs allow
direct input of slow or noisy signals.
Like the PEEL18CV8, the PEEL18LV8Z is a logical
superset of the industry standard PAL16V8 SPLD. The
PEEL18LV8Z provides additional architectural features that
allow more logic to be incorporated into the design. ICT's
JEDEC file translator allows easy conversion of existing 20
pin PLD designs to the PEEL18LV8Z architecture without
the need for redesign. The PEEL18LV8Z architecture
allows it to replace over twenty standard 20-pin DIP, SOIC,
TSSOP and PLCC packages Pin Configuration.
C LK M U X (O ptional)
I/C LK1
I
I
I
I
I
I
I
I
GN D
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
I/C LK1
I
I
I
I
I
I
I
I
GN D
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
C C
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
ª
D IP
I/CLK1
VCC
I/O
I/O
I/O
TS S O P
I/C LK1
3
I
I
I
I
I
4
5
6
7
8
9 10 11 12 13
2
1 20 19
18
17
16
15
14
I/O
I/O
I/O
I/O
I/O
I
I
I
I
I
I
I
I
GN D
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
V
CC
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
I
GND
I
I/O
P L C C -J
I/O
S O IC
Figure 1 - Pin Configuration
Figure 2 - Block Diagram
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(OPTIONAL)
0
3
4
7
8
11
12
15
16
19
20
23
24
27
28
31
32
35
112
0
1
2
ASYNCHRONOUS CLEAR
(TO ALL MACROCELLS)
9
MACRO
CELL
19
I/O
I/CLK
1
10
11
20
MACRO
CELL
18
I/O
I
2
21
22
MACRO
CELL
33
17
I/O
I
3
34
35
MACRO
CELL
48
16
I/O
I
4
49
50
I/O
MACRO
CELL
65
15
I
5
66
67
I/O
MACRO
CELL
82
14
I
6
83
84
MACRO
CELL
97
13
I/O
I
7
98
99
MACRO
CELL
110
12
I/O
I
8
111
I
9
SYNCHRONOUS PRESET
(TO ALL MACROCELLS)
11
I
Figure 3 - PEEL18LV8Z Logic Array Diagram
Function Description
The PEEL18LV8Z implements logic functions as sum-of-
products expressions in a programmable-AND/fixed-OR
logic array. Programming the connections of input signals
into the array creates user-defined functions. User-
configurable output structures in the form of I/O macrocells
further increase logic flexibility.
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Architecture Overview
The PEEL18LV8Z architecture is illustrated in the block
diagram of Figure 14. 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 PEEL18LV8Z can implement
up to 8 sum-of-products logic expressions.
Associated with each of the 8 OR functions is an I/O
macrocell 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.
AND/OR Logic Array
The programmable AND array of the PEEL18LV8Z (shown
in Figure 15) 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
Macrocell Architecture
Each I/O macrocell, as shown in Figure 4, consists of a D-
type flip-flop and two signal-select multiplexers. The four
EEPROM bits controlling these multiplexers determine the
configuration of each macrocell. 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 circuits for the twelve macrocell configurations
are illustrated in Figure 5. In addition to emulating the four
PAL-type output structures (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
or active-low logic. Programmable polarity eliminates the
need for external inverters.
on unused product terms so that they will have no effect on
the output function).
Variable Product Term Distribution
The PEEL18LV8Z provides 113 product terms to drive the
8 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 15). This distribution allows
optimum use of the device resources.
Programmable I/O Macrocell
The unique twelve-configuration output macrocell provides
complete control over the architecture of each output. The
ability to configure each output independently lets you to
tailor the configuration of the PEEL18LV8Z to the precise
requirements of your design.
•
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 connected 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 PEEL18LV8Z, the device
programmer 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 programming selected
connections in the AND array. (Note that PEEL device
programmers automatically program all of the connections
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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 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 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 PEEL18LV8Z 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
Schmitt Trigger Inputs
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).
The PEEL18LV8Z has Schmitt trigger input buffers on all
inputs, including the clock. Schmitt trigger inputs allow
direct input of slow signals such as biomedical and sine
waves or clocks. They are also useful in cleaning up noisy
signals. This makes the PEEL18LV8Z especially desirable
in portable applications where the environment is less
predictable.
Zero Power Feature
The CMOS PEEL18LV8Z 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 three t
PD
's, the outputs are latched in their
current state and the device automatically 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
savings can be realized for combinatorial or sequential
operations when the inputs or clock change at a modest
rate. See Figure 6.
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 function, 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 PEEL18LV8Z is a programmable
clock multiplexer that allows the user to select true or
complement forms of either input pin or product-term clock
sources.
Operates in both 3 Volt and 3.3 Volt Systems
The PEEL18LV8Z is designed to operate with a V
CC
range
of 2.7 to 3.6 Volts D.C. This allows operation in both 3 Volt
10% (battery operated) and 3.3 Volt 10% (power supply
operated) systems. The propagation delay t
PD
is 5 ns
slower at the lower voltage, but this is typically not an issue
in battery-operated systems (see - A.C. Electrical
CharacteristicsTable 1 - Absolute Maximum Ratings- A.C.
Electrical Characteristics).
Figure 4 - PEEL18LV8Z I/O Macro cell
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
5.)
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PEEL 18LV8Z
When the PEEL18LV8Z is powered up, a built-in feature
holds the outputs in tri-state until Vcc reaches 2.2V. This
prevents output transitions during power-up.
Figure 5 - Equivalent Circuits for the twelve configurations of the PEEL18LV8Z I/O Macrocell
Configuration
#
1
2
3
4
5
6
7
8
9
10
11
12
A
0
1
0
1
0
1
0
1
0
1
0
1
B
0
0
1
1
0
0
1
1
0
0
1
1
C
1
1
0
0
1
1
1
1
0
0
1
1
D
0
0
0
0
1
1
1
1
0
0
0
0
Register
Bi-directional I/O
Combinatorial
Register
Combinatorial Feedback
Combinatorial
Register
Register Feedback
Combinatorial
Active Low
Active High
Active Low
Active High
Active Low
Active High
Active Low
Active High
Active Low
Active High
Active Low
Active High
Input/Feedback Select
Output Select
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