CY7C964A Datasheet, PDF (1/6 Pages) Cypress Semiconductor – Bus Interface Logic Circuit

PRELIMINARY
CY7C964A
Features
• Comparators, counters, latches, and drivers minimize
logic requirements for a variety of multiplexed and
non-multiplexed buses
• Directly drives VMEbus address and data signals
• 8-bit comparator for slave address decoding
• Flexible interface optimized for VMEbus applications
• Companion device to Cypress VMEbus family of com-
ponents
• Replaces multiple SSI/MSI components
• Cascadable
• 64-pin QFP
• See the VMEbus Interface Handbook for more informa-
tion
Functional Description
The CY7C964A integrates several space-consuming functions
into one small package, freeing board space for the implemen-
tation of added-value board features. It contains counters,
comparators, latches, and drivers configured to be of value to
implementors of any backplane interface with address and
data buses, particularly VMEbus interfaces. The on-chip driv-
ers are suitable for driving the VMEbus directly. The
CY7C964A is ideal in applications where high-performance
and real estate are primary concerns.
Although having many applications, the Bus Interface Logic
Circuit is an ideal companion part to Cypress’s VMEbus family
of components, the VIC068A, VIC64, and the CY7C960A. It is
intended to drive the address and data buses, so three or four
of these small devices are needed per controller. In every
Bus Interface Logic Circuit
case, the controllers provide the control and timing signals to
the Bus Interface Logic Circuit as it acts as a bridge between
the VMEbus and the Local bus.
Application with VMEbus Architecture
Use with Cypress VMEbus Controllers
The CY7C964A Bus Interface Logic Circuit is a seamless in-
terface between the VIC068A/VIC64 and the VMEbus signals.
The device functions equally well in the established 32-bit
VMEbus arena and the new 64-bit VMEbus standard. The de-
vice contains three 8-bit counters to fulfill the functions of Block
counters, and DMA counters as implied by the D64 portion of
the VMEbus specification. It also contains the necessary mul-
tiplexing logic to allow the 64-bit-wide VMEbus path to be fun-
nelled to and from the 32-bit local bus. Control circuitry is in-
cluded to manage the switching of the 32-bit address bus
during normal (32-bit) operations, and during MBLT (64-bit)
operations. The on-chip drivers are capable of driving the
VMEbus directly (48 mA).
Use in Other VMEbus Controller Implementations
The CY7C964A circuitry is designed to be of use to designers
of VMEbus circuitry, including VSB (VME subsystem bus) and
designs not requiring the features of the Cypress VIC068A,
VIC64, and CY7C960A. The logic diagram includes gener-
al-purpose blocks of comparators, counters, and latches that
can be controlled using the flexible control interface to allow
many different options to be implemented. Although the device
is offered in a small 64-pin package, the use of multiplexed
input and output pins provides access to the many internal
functions, thus saving external circuitry.
Pin Configuration
PQFP/CQFP/TQFP
Top View
GND
1
LD7
2
LDS
3
FC1
4
STROBE*
5
MWB*
6
LCOUT*
7
GND
8
VCOMP*
9
VCOUT*
10
LADO
11
LADI
12
LEDI
13
LEDO
14
A7
15
GND
16
48
GND
47
LD0
46
LA0
45
DENIN*
44
DENIN1*
43
LAEN
42
LCIN*
41
VCIN*
40
VCC
39
BLT*
38
D64
37
DENO*
36
ABEN*
35
D0
34
A0
33
GND
C964A-1
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
Document #: 38-09001 Rev. *A
Revised June 12, 2001