ADCMP600_11 AD [Analog Devices], ADCMP600_11 Datasheet - Page 12

• Manufacturer Part Number: ADCMP600_11
• Description: Rail-to-Rail, Very Fast, 2.5 V to 5.5 V
• Manufacturer: AD [Analog Devices]

ADCMP600/ADCMP601/ADCMP602
Leaving the LE/HYS pin disconnected results in a fixed
hysteresis of 2 mV; driving this pin high removes hysteresis. The
maximum hysteresis that can be applied using this pin is
approximately 160 mV. Figure 21 illustrates the amount of
hysteresis applied as a function of the external resistor value,
and Figure 11 illustrates hysteresis as a function of the current.
The hysteresis control pin appears as a 1.25 V bias voltage seen
through a series resistance of 7 kΩ. The bias voltage changes
± 20% throughout the hysteresis control range. The advantages
of applying hysteresis in this manner are improved accuracy,
improved stability, reduced component count, and maximum
versatility. An external bypass capacitor is not recommended on
the HYS pin because it impairs the latch function and often
degrades the jitter performance of the device. As described in the
Using/Disabling the Latch Feature section, hysteresis control
need not compromise the latch function.
CROSSOVER BIAS POINT
In both op amps and comparators, rail-to-rail inputs of this type
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 the measured offset voltages and currents change.
The ADCMP600/ADCMP601/ADCMP602 comparators
slightly elaborate on this scheme. Crossover points can be found
at approximately 0.8 V and 1.6 V.
CC
rail and others are active near the GND rail. At some predeter-
CC
/2, the direction of the bias current reverses
Rev. A | Page 12 of 16
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 is observed. This oscillation is due to
the high gain bandwidth of the comparator in combination with
feedback parasitics in the package and PC board. In many
applications, chattering is not harmful.
250
200
150
100
50
0
50
V
CC
V
Figure 21. Hysteresis vs. R
CC
= 2.5V
= 5.5V
150
HYSTERESIS RESISTOR (kΩ)
250
350
HYS
Control Resistor
450
550
650