Datasheet AD8468 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | Rail-to-Rail, Fast, Low Power 2.5 V to 5.5 V, Single-Supply TTL/CMOS Comparator |
| Pages / Page | 12 / 8 — AD8468. Data Sheet. 500mV OVERDRIVE. CROSSOVER BIAS POINT. INPUT VOLTAGE. … |
| Revision | A |
| File Format / Size | PDF / 273 Kb |
| Document Language | English |
AD8468. Data Sheet. 500mV OVERDRIVE. CROSSOVER BIAS POINT. INPUT VOLTAGE. 10mV OVERDRIVE. VN ± VOS. DISPERSION. Q OUTPUT
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Text Version of Document
link to page 7
AD8468 Data Sheet 500mV OVERDRIVE CROSSOVER BIAS POINT
Rail-to-rail inputs of this type, in both op amps and comparators,
INPUT VOLTAGE
have a dual front-end design. Certain devices are active near the
10mV OVERDRIVE
VCC rail and others are active near the VEE rail or ground. At some
VN ± VOS
predetermined point in the common-mode range, a crossover occurs. At this point, normally VCC/2, the direction of the bias current reverses, and there are changes in measured offset
DISPERSION
0 voltages and currents. -01 3
Q OUTPUT
85 08 The AD8468 slightly elaborates on this scheme. Crossover Figure 10. Propagation Delay—Overdrive Dispersion points can be found at approximately 0.8 V and 1.6 V.
MINIMUM INPUT SLEW RATE REQUIREMENT INPUT VOLTAGE 1V/ns
With the rated load capacitance and normal good PC board design practice, as discussed in the Optimizing Performance
VN ± VOS 10V/ns
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
DISPERSION
poor bypassing, oscillation may be encountered. These oscilla- 11 0 3-
Q OUTPUT
tions are due to the high gain bandwidth of the comparator in 85 08 Figure 11. Propagation Delay—Slew Rate Dispersion combination with feedback through parasitics in the package and PC board. In many applications, chattering is not harmful. Rev. A | Page 8 of 12 Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS INFORMATION POWER/GROUND LAYOUT AND BYPASSING TTL-/CMOS-COMPATIBLE OUTPUT STAGE OPTIMIZING PERFORMANCE COMPARATOR PROPAGATIONDELAY DISPERSION CROSSOVER BIAS POINT MINIMUM INPUT SLEW RATE REQUIREMENT TYPICAL APPLICATION CIRCUITS OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS
AD8468 Data Sheet 500mV OVERDRIVE CROSSOVER BIAS POINT
Rail-to-rail inputs of this type, in both op amps and comparators,
INPUT VOLTAGE
have a dual front-end design. Certain devices are active near the
10mV OVERDRIVE
VCC rail and others are active near the VEE rail or ground. At some
VN ± VOS
predetermined point in the common-mode range, a crossover occurs. At this point, normally VCC/2, the direction of the bias current reverses, and there are changes in measured offset
DISPERSION
0 voltages and currents. -01 3
Q OUTPUT
85 08 The AD8468 slightly elaborates on this scheme. Crossover Figure 10. Propagation Delay—Overdrive Dispersion points can be found at approximately 0.8 V and 1.6 V.
MINIMUM INPUT SLEW RATE REQUIREMENT INPUT VOLTAGE 1V/ns
With the rated load capacitance and normal good PC board design practice, as discussed in the Optimizing Performance
VN ± VOS 10V/ns
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
DISPERSION
poor bypassing, oscillation may be encountered. These oscilla- 11 0 3-
Q OUTPUT
tions are due to the high gain bandwidth of the comparator in 85 08 Figure 11. Propagation Delay—Slew Rate Dispersion combination with feedback through parasitics in the package and PC board. In many applications, chattering is not harmful. Rev. A | Page 8 of 12 Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS INFORMATION POWER/GROUND LAYOUT AND BYPASSING TTL-/CMOS-COMPATIBLE OUTPUT STAGE OPTIMIZING PERFORMANCE COMPARATOR PROPAGATIONDELAY DISPERSION CROSSOVER BIAS POINT MINIMUM INPUT SLEW RATE REQUIREMENT TYPICAL APPLICATION CIRCUITS OUTLINE DIMENSIONS ORDERING GUIDE AUTOMOTIVE PRODUCTS
