CY7C346
USE ULTRA37000TM FOR
ALL NEW DESIGNS
Document #: 38-03005 Rev. *B
Page 4 of 21
Logic Array Blocks
There are eight logic array blocks in the CY7C346. Each LAB
consists of a macrocell array containing 16 macrocells, an
expander product term array containing 32 expanders, and an
I/O block. The LAB is fed by the programmable interconnect
array and the dedicated input bus. All macrocell feedbacks go
to the macrocell array, the expander array, and the program-
mable interconnect array. Expanders feed themselves and the
macrocell array. All I/O feedbacks go to the programmable
interconnect array so that they may be accessed by macro-
cells in other LABs as well as the macrocells in the LAB in
which they are situated.
Externally, the CY7C346 provides 20 dedicated inputs, one of
which may be used as a system clock. There are 64 I/O pins
that may be individually configured for input, output, or bidirec-
tional data flow.
Programmable Interconnect Array
The Programmable Interconnect Array (PIA) solves inter-
connect limitations by routing only the signals needed by each
logic array block. The inputs to the PIA are the outputs of every
macrocell within the device and the I/O pin feedback of every
pin on the device.
Timing Delays
Timing delays within the CY7C346 may be easily determined
using Warp®
, Warp Professional™, or Warp Enterprise™
software. The CY7C346 has fixed internal delays, allowing the
user to determine the worst case timing delays for any design.
Design Recommendations
Operation of the devices described herein with conditions
above those listed under “Maximum Ratings” may cause
permanent damage to the device. This is a stress rating only
and functional operation of the device at these or any other
conditions above those indicated in the operational sections of
this data sheet is not implied. Exposure to absolute maximum
ratings conditions for extended periods of time may affect
device reliability. The CY7C346 contains circuitry to protect
device pins from high static voltages or electric fields, but
normal precautions should be taken to avoid application of any
voltage higher than the maximum rated voltages.
For proper operation, input and output pins must be
constrained to the range GND
≤ (V
IN or VOUT) ≤ VCC. Unused
inputs must always be tied to an appropriate logic level
(either VCC or GND). Each set of VCC and GND pins must
be connected together directly at the device. Power supply
decoupling capacitors of at least 0.2
µF must be connected
between VCC and GND. For the most effective decoupling,
each VCC pin should be separately decoupled to GND
directly at the device. Decoupling capacitors should have
good frequency response, such as monolithic ceramic types
have.
Design Security
The CY7C346 contains a programmable design security
feature that controls the access to the data programmed into
the device. If this programmable feature is used, a proprietary
design implemented in the device cannot be copied or
retrieved. This enables a high level of design control to be
Figure 1. CY7C346 Internal Timing Model
LOGIC ARRAY
CONTROL DELAY
tLAC
EXPANDER
DELAY
tEXP
CLOCK
DELAY
tIC
tRD
tCOMB
tLATCH
INPUT
DELAY
tIN
REGISTER
OUTPUT
DELAY
tOD
tXZ
tZX
LOGIC ARRAY
DELAY
tLAD
FEEDBACK
DELAY
tFD
OUTPUT
INPUT
SYSTEM CLOCK DELAY tICS
tRH
tRSU
tPRE
tCLR
PIA
DELAY
tPIA
I/O DELAY
tIO
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