Datasheet

7–138
CMOS Output Characteristics (ALVC, LVC, and LV)
Figure 7 also shows a simplified LV, LVC, and ALVC output stage. LV and ALVC are pure 3.3-V families. They cannot be
used to translate between 5-V and 3.3-V environments. ALVC is currently the fastest CMOS logic available. It is used primarily
for high-speed memory and point-to-point applications with medium drive capability (±24 mA). LV is designed for low-speed,
low-drive (±8–6 mA) applications. It is similar to HC and HCT. LVC, on the other hand, is used for on-board and memory
applications that require medium performance and medium drive logic, as well as translation between 5-V and 3.3-V signals.
These parts have the same drive characteristics as ALVC devices. Not only can LVC devices operate as 3-V- to 5-V-level
translators by supporting 5.5-V input or I/O voltages (V
CC
= 3 V to 3.6 V), but the inputs can withstand 5.5 V, even when
V
CC
= 0 V. This permits the devices to be used under partial system power-down and live-insertion applications.
The I
OH
/V
OH
and I
OL
/V
OL
curves for the above familes are shown in Figures 8 and 9. With their specified I
OL
and I
OH
, some
of these families will accommodate many standard bus specifications. However, these devices are capable of driving well
beyond these limits. This is important when considering switching a low-impedance backplane on the incident wave. CBT,
on the other hand, has no drive capability; its output impedance is purely resistive (V = I*R) as shown in Figures 2, 8, and 9.
0 102030405060708090100
0 102030405060708090100
V
OL
– V
4
3.6
2.8
2
1.6
0.8
0
3.2
2.4
1.2
0.4
3.3-V Families
5-V Families
V
OL
– V
4
3.6
2.8
2
1.6
0.8
0
3.2
2.4
1.2
0.4
T
A
= 25°C,
V
CC
= 5 V,
V
IH
= 3 V,
V
IL
= 0 V
I
OL
– mA
I
OL
– mA
T
A
= 25°C,
V
CC
= 3.3 V,
V
IH
= 3 V,
V
IL
= 0 V
LV
LVT2
LVC
ALVC
LVT
ABT
ABTE
ABT2
Figure 8. Output-Low Characteristic Impedance of 3.3-V and 5-V Families