
Philips Semiconductors
Product specification
74ABT657
Octal transceiver with parity generator/checker
(3-State)
1995 Dec 11
7
AC CHARACTERISTICS
GND = 0V; tR = tF = 2.5ns; CL = 50pF, RL = 500
LIMITS
SYMBOL
PARAMETER
WAVEFORMS
Tamb = +25oC
VCC = +5.0V
Tamb = –40 to +85oC
VCC = +5.0V ±10%
UNIT
Min
Typ
Max
Min
Max
tPLH
tPHL
Propagation delay
An to Bn or Bn to An
2
1.1
1.2
3.3
3.0
5.0
4.3
1.1
1.2
5.5
4.8
ns
tPLH
tPHL
Propagation delay
An to PARITY
1, 2
2.5
2.8
6.5
7.0
8.7
9.1
2.5
2.8
10.1
10.6
ns
tPLH
tPHL
Propagation delay
ODD/EVEN to PARITY, ERROR
1, 2
1.7
1.9
5.0
6.6
1.7
1.9
7.3
ns
tPLH
tPHL
Propagation delay
Bn to ERROR
1, 2
3.9
4.0
9.2
9.6
11.7
12.1
3.9
4.0
13.8
14.5
ns
tPLH
tPHL
Propagation delay
PARITY to ERROR
1, 2
2.7
3.2
6.0
6.4
7.6
8.0
2.7
3.2
9.4
ns
tPZH
tPZL
Output enable time1
to High or Low level
3, 4
1.3
1.9
3.8
4.4
5.6
7.0
1.3
1.9
6.6
8.2
ns
tPHZ
tPLZ
Output disable time
from High or Low level
3, 4
2.4
2.7
5.1
5.4
7.0
7.6
2.4
2.7
7.6
8.1
ns
NOTES:
1. These delay times reflect the 3-State recovery time only and do not include the delay through the buffers and the parity check circuitry which
affect the ERROR output. To assure
valid information at the ERROR pin, time must be allowed for the signal to propagate through the
drivers (B to A), through the parity check circuitry (same as A to PARITY), and to the ERROR output.
Valid data at the ERROR pin
≥ (B to A)
+ (A to PARITY).
AC WAVEFORMS
NOTE: For all waveforms, VM = 1.5V.
An, Bn
ODD/EVEN
PARITY
VM
tPHL
tPLH
VM
PARITY,
ERROR
An, Bn
ODD/EVEN
PARITY
VM
tPHL
tPLH
VM
PARITY,
ERROR
SA00219
Waveform 1. Propagation Delay For Inverting Output
OE
VM
tPZH
tPHZ
0V
VOH –0.3V
VM
An, Bn
PARITY, ERROR
SA00221
Waveform 3. 3-State Output Enable Time to High Level and
Output Disable Time from High Level
SA00220
VM
tPLH
tPHL
VM
An, Bn
ODD/EVEN
PARITY
An, Bn,
PARITY,
ERROR
Waveform 2. Propagation Delay For Non-Inverting Output
SA00222
tPZL
tPLZ
0V
VOL +0.3V
VM
OE
An, Bn
PARITY, ERROR
Waveform 4. 3-State Output Enable Time to Low Level and
Output Disable Time from Low Level