Datasheet

7–136
Table 1. Input Transition Rise or Fall Rate as Specified in Data Sheets
recommended operating conditions
MIN MAX UNIT
†
ABT octals, FB (A port) 5
∆t/∆v
In
p
ut transition rise or fall rate
†
ABT Widebus, Widebus+ 10
ns/V
∆t/∆
v
Inp
u
t
transition
rise
or
fall
rate
†
LVT, LVC, ALVC, GTL (A port) 10
ns/V
LV 100
†
Unless otherwise noted in data sheets
Figure 5 shows the input characteristic impedance of both 3.3-V and 5-V families. One can see the effect of the clamping diodes
when the input is below ground (all families) and above V
CC
for LV only.
–90
–70
–50
–30
–10
10
30
50
70
90
–90
–70
–50
–30
–10
10
30
50
70
90
I
IN
– mA
–1 –0.5 0 1.5 2 2.5 3 3.5 4 4.5 5 5.5
6
0.5 1
3.3-V Families
T
A
= 25°C,
V
CC
= 3 V,
V
IH
= 3 V,
V
IL
= 0 V
5-V Families
T
A
= 25°C,
V
CC
= 5 V,
V
IH
= 3 V,
V
IL
= 0 V
–1 –0.5 0 1.5 2 2.5 3 3.5 40.5 1
V
IN
– Input Voltage – V
I
IN
– mA
‡
Octal, Widebus, and Widebus+ devices with series damping resistor on the output (25 Ω typical)
LVT2
‡
ALVC
LV
LVC
LVT
ABT
ABT2
‡
ABTE
GTL
FB
CBT
V
IN
– Input Voltage – V
Figure 5. Input Characteristics Impedance of 3.3-V and 5-V Families
BiCMOS Output Characteristics (ABT and LVT)
Figure 6 is a simplified schematic of an ABT output stage. Data is transmitted to the gate of M1, which acts as a simple current
switch. When M1 is turned on, current flows through R1 and M1 to the base of Q4, turning it on and driving the output low.
At the same time, the base of Q2 is pulled low, turning off the upper output. For a low-to-high transition, the gate of M1 must
be driven low, turning M1 off. Current through R1 will charge the base of Q2, pulling it high and turning on the Darlington
pair, consisting of Q2 and Q3. Meanwhile, with its supply of base drive cut off, Q4 turns off, and the output switches from low
to high. R2 is used to limit output current in the high state, and D1 is a blocking diode used to prevent reverse current flow
in specific power-down applications. LVT I/Os have characteristics similar to ABT, with added CMOS pullup and pulldown
for rail-to-rail switching.