Specifications GAL6002
Array Description
Register Preload
The GAL6002 contains two E2 reprogrammable arrays. The first is When testing state machine designs, all possible states and state
anAND array and the second is an OR array. These arrays are de- transitions must be verified, not just those required during normal
scribed in detail below.
operations. This is because certain events may occur during sys-
tem operation that cause the logic to be in an illegal state (power-
up, line voltage glitches, brown-out, etc.). To test a design for proper
AND ARRAY
TheAND array is organized as 78 inputs by 75 product term outputs. treatment of these conditions, a method must be provided to break
The 10 ILMCs, 10 IOLMCs, 8 BLMC feedbacks, 10 OLMC feed- the feedback paths and force any desired state (i.e., illegal) into the
backs, and ICLK comprise the 39 inputs to this array (each available registers. Then the machine can be sequenced and the outputs
in true and complement forms). 64 product terms serve as inputs tested for correct next state generation.
to the OR array. The RESET product term generates the RESET
signal described in the Output and Buried Logic Macrocells sec- All of the registers in the GAL6002 can be preloaded, including the
tion. There are 10 output enable product terms which allow device ILMC, IOLMC, OLMC, and BLMC registers. In addition, the con-
I/O pins to be bi-directional or tri-state.
tents of the state and output registers can be examined in a special
diagnostics mode. Programming hardware takes care of all preload
timing and voltage requirements.
OR ARRAY
The OR array is organized as 64 inputs by 36 sum term outputs.
64 product terms from theAND array serve as the inputs to the OR
array. Of the 36 sum term outputs, 18 are data (“D”) terms and 18
are enable/clock (“E”) terms. These terms feed into the 10 OLMCs
and 8 BLMCs, one “D” term and one “E” term to each.
Latch-Up Protection
GAL6002 devices are designed with an on-board charge pump to
negatively bias the substrate. The negative bias is of sufficient
magnitude to prevent input undershoots from causing the circuitry
to latch. Additionally, outputs are designed with n-channel pull-ups
instead of the traditional p-channel pull-ups to eliminate any pos-
sibility of SCR induced latching.
The programmable OR array offers unparalleled versatility in prod-
uct term usage. This programmability allows from 1 to 64 product
terms to be connected to a single sum term. A programmable OR
array is more flexible than a fixed, shared, or variable product term
architecture.
Input Buffers
Electronic Signature
GAL6002 devices are designed with TTL level compatible input
buffers. These buffers have a characteristically high impedance,
and present a much lighter load to the driving logic than bipolar TTL
devices.
An electronic signature is provided with every GAL6002 device. It
contains 72 bits of reprogrammable memory that can contain user
defined data. Some uses include user ID codes, revision numbers,
or inventory control. The signature data is always available to the
user independent of the state of the security cell.
GAL6002 input buffers have active pull-ups within their input struc-
ture. This pull-up will cause any un-terminated input or I/O to float
to a TTL high (logical 1). Lattice Semiconductor recommends that
all unused inputs and tri-stated I/O pins be connected to another
active input, Vcc, or GND. Doing this will tend to improve noise
NOTE: The electronic signature is included in checksum calcula-
tions. Changing the electronic signature will alter the checksum.
immunity and reduce Icc for the device.
Security Cell
Typical Input Pull-up Characteristic
A security cell is provided with every GAL6002 device as a deterrent
to unauthorized copying of the array patterns. Once programmed,
this cell prevents further read access to the AND array. This cell
can be erased only during a bulk erase cycle, so the original con-
figuration can never be examined once this cell is programmed.
The Electronic Signature is always available to the user, regard-
less of the state of this control cell.
0
- 2 0
- 4 0
- 6 0
Device Programming
0
1 . 0
2 . 0
3 . 0
4 . 0
5 . 0
Input Voltage (Volts)
GAL devices are programmed using a Lattice Semiconductor-
approved Logic Programmer, available from a number of manufac-
turers. Complete programming of the device takes only a few
seconds. Erasing of the device is transparent to the user, and is
done automatically as part of the programming cycle.
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Linear [ Linear ]
