ad8468 Analog Devices, Inc., ad8468 Datasheet - Page 8

• Manufacturer Part Number: ad8468
• Description: Rail-to-rail, Fast, Low Power 2.5 V To 5.5 V, Single-supply Ttl/cmos Comparator
• Manufacturer: Analog Devices, Inc.

AD8468
INPUT VOLTAGE
Q OUTPUT
INPUT VOLTAGE
Q OUTPUT
Figure 10. Propagation Delay—Overdrive Dispersion
Figure 11. Propagation Delay—Slew Rate Dispersion
10V/ns
1V/ns
500mV OVERDRIVE
10mV OVERDRIVE
DISPERSION
DISPERSION
V
V
N
N
± V
± V
OS
OS
Rev. PrA | Page 8 of 12
CROSSOVER BIAS POINT
Rail-to-rail inputs of this type, in both op amps and comparators,
have a dual front-end design. Certain devices are active near the
V
mined point in the common-mode range, a crossover occurs. At
this point, normally V
and there are changes in measured offset voltages and currents.
The AD8468 slightly elaborates on this scheme. Crossover
points can be found at approximately 0.8 V and 1.6 V.
MINIMUM INPUT SLEW RATE REQUIREMENT
With the rated load capacitance and normal good PC board
design practice, as discussed in the Optimizing Performance
section, these comparators should be stable at any input slew
rate with no hysteresis. Broadband noise from the input stage is
observed in place of the violent chattering seen with most other
high speed comparators. With additional capacitive loading or
poor bypassing, oscillation may be encountered. These oscilla-
tions are due to the high gain bandwidth of the comparator in
combination with feedback through parasitics in the package
and PC board. In many applications, chattering is not harmful.
CC
rail and others are active near the V
Preliminary Technical Data
CC
/2, the direction of the bias current reverses
EE
rail. At some predeter-