DM74AS651 鈥?DM74AS652 Octal Bus Transceiver and Register
October 1986
Revised March 2000
DM74AS651 鈥?DM74AS652
Octal Bus Transceiver and Register
General Description
These devices incorporate an octal transceiver and an
octal D-type register configured to enable transmission of
data from bus to bus or internal register to bus. The
DM74AS651 offers 64-Industrial grade product guarantee-
ing performance from
鈭?0擄C
to
+85擄C.
These bus transceivers feature totem-pole 3-STATE out-
puts designed specifically for driving highly-capacitive or
relatively low-impedance loads. The high-impedance state
and increased high-logic-level drive provide these devices
with the capability of being connected directly to and driv-
ing the bus lines in a bus-organized system without need
for interface or pull-up components. They are particularly
attractive for implementing buffer registers, I/O ports, bidi-
rectional bus drivers, and working registers.
The registers in the DM74AS651 and DM74AS652 are
edge-triggered D-type flip-flops. On the positive transition
of the clock (CAB or CBA), the input data is stored.
The SAB and SBA control pins are provided to select
whether real-time data or stored data is transferred. A LOW
input level selects real-time data and a HIGH level selects
stored data. The select controls have a 鈥渕ake before
break鈥?configuration to eliminate a glitch which would nor-
mally occur in a typical multiplexer during the transition
between stored and real-time data.
The Enable (GAB and GBA) control pins provide four
modes of operation; real-time data transfer from bus A-to-
B, real-time data transfer from bus B-to-A, real-time bus A
and/or B data transfer to internal storage, or internal stored
data transfer to bus A and/or B.
Features
s
Switching specifications at 50 pF
s
Switching specifications guaranteed over full tempera-
ture and V
CC
range
s
Advanced oxide-isolated, ion-implanted Schottky TTL
process
s
3-STATE buffer-type outputs drive bus lines directly
s
Guaranteed performance over industrial temperature
range (鈭?0擄C to
+85擄C)
in 64-grade products
Ordering Code:
Order Number
DM74AS651WM
DM74AS651NT
DM74AS652WM
DM74AS652NT
Package Number
M24B
N24C
M24B
N24C
Package Description
24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-100, 0.300 Wide
24-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
24-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-100, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter 鈥淴鈥?to the ordering code.
漏 2000 Fairchild Semiconductor Corporation
DS006325
www.fairchildsemi.com
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