Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

AD9698TQ Datasheet(PDF) 6 Page - Analog Devices

Part # AD9698TQ
Description  Ultrafast TTL Comparators
Download  8 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  AD [Analog Devices]
Direct Link  http://www.analog.com
Logo AD - Analog Devices

AD9698TQ Datasheet(HTML) 6 Page - Analog Devices

  AD9698TQ Datasheet HTML 1Page - Analog Devices AD9698TQ Datasheet HTML 2Page - Analog Devices AD9698TQ Datasheet HTML 3Page - Analog Devices AD9698TQ Datasheet HTML 4Page - Analog Devices AD9698TQ Datasheet HTML 5Page - Analog Devices AD9698TQ Datasheet HTML 6Page - Analog Devices AD9698TQ Datasheet HTML 7Page - Analog Devices AD9698TQ Datasheet HTML 8Page - Analog Devices  
Zoom Inzoom in Zoom Outzoom out
 6 / 8 page
background image
AD9696/AD9698
–6–
REV. B
R
R
A2
A1
AD9698
+IN1
–IN1
+VREF
R1
Q1 OUT
R = 10k
R1 + R2 >5kΩ
A1 ,A2 = AD708 or OP– 290
(±5V)
(+5V)
R2
Q1 OUT
Q1 OUT
Q2 OUT
Q2 OUT
+Q2 OUT
–VREF
VSIGNAL
VIN
+IN2
–IN2
Figure 1. AD9698 Used as Window Detector
When configured as shown, the op amps generate reference lev-
els for the comparators that are equally spaced above and below
the applied VIN. The width of the window is established by the
ratio of R1 and R2. For a given ratio of R1 and R2, +VREF and
–VREF will be fixed percentages above and below VIN. As an ex-
ample, using 2.2 k
Ω for R1 and 10 kΩ for R2 creates a ±10%
window. When VIN equals +3 V, +VREF will be +3.3 V and
–VREF will be +2.7 V. Likewise, for a –2 V input, the thresholds
will be –1.8 V and –2.2 V. Windows of differing percentage
width can be calculated with the equation:
(1–X)/2X = R2/R1
where:
X = % window
Additionally, the low impedance of the op amp outputs assures
that the threshold voltages will remain constant when the input
currents change as the signal passes through the threshold volt-
age levels.
The output of the AND gate will be high while the signal is in-
side the window. Q1OUT will be high when the signal is above
+VREF, and Q2OUT will be high when the signal is below –VREF.
Crystal Oscillator
Oscillators are used in a wide variety of applications from audio
circuits to waveform generators, from ATE triggers and tele-
communications transceivers to radar. Figure 2 shows a versatile
and inexpensive oscillator. The circuit uses the AD9696, in a
positive feedback mode, and is capable of generating accurate
and stable oscillations with frequencies ranging from 1 MHz to
more than 40 MHz.
To generate oscillations from 1 to 25 MHz, a fundamental
mode crystal is used without the dc blocking capacitor and
choke. The parallel capacitor on the inverting input is selected
for stability (0.1
µF for 1–10 MHz; 220 pF for frequencies
above 10 MHz).
APPLICATIONS
General
Two characteristics of the AD9696 and AD9698 should be con-
sidered for any application. First is the fact that all TTL com-
parators are prone to oscillate if the inputs are close to equal for
any appreciable period of time. One instance of this happening
would be slow changes in the unknown signal; the probability of
oscillation is reduced when the unknown signal passes through
the threshold at a high slew rate. Another instance is if the un-
known signal does not overdrive the comparator logic. Unless
they are overdriven, TTL comparators have undershoot when
switching logic states. The smaller the overdrive, the greater the
undershoot; when small enough, the comparator will oscillate,
not being able to determine a valid logic state. For the AD9696
and AD9698, 20 mV is the smallest overdrive which will assure
crisp switching of logic states without significant undershoot.
The second characteristic to keep in mind when designing
threshold circuits for these comparators is twofold: (1) bias cur-
rents change when the threshold is exceeded; and (2) ac input
impedance decreases when the comparator is in its linear region.
During the time both transistors in the differential pair are con-
ducting, the ac input impedance drops by orders of magnitude.
Additionally, the input bias current switches from one input to
the other, depending upon whether or not the threshold is ex-
ceeded. As a result, the input currents follow approximately the
characteristic curves shown below.
{
SIGNAL
VOLTAGE
AT +INPUT
+INPUT
CURRENT
– INPUT
CURRENT
LINEAR
REGION
Threshold Input Currents
This characteristic will not cause problems unless a high imped-
ance threshold circuit or drive circuit is employed. A circuit
similar to that shown in the window comparator application can
eliminate this possible problem.
Window Comparator
Many applications require determining when a signal’s voltage
falls within, above, or below a particular voltage range. A simple
tracking window comparator can provide this data. Figure 1
shows such a window comparator featuring high speed, TTL
compatibility, and ease of implementation.
Two comparators are required to establish a “window” with up-
per and lower threshold voltages. The circuit shown uses the
AD9698 dual ultrafast TTL comparator. In addition to the cost
and space savings over a design using two single comparators,
the dual comparator on a single die produces better matching of
both dc and dynamic characteristics.


Similar Part No. - AD9698TQ

ManufacturerPart #DatasheetDescription
logo
Analog Devices
AD9690 AD-AD9690 Datasheet
2Mb / 77P
   14-Bit, 1 GSPS/500 MSPS JESD204B, Analog-to-Digital Converter
AD9690 AD-AD9690 Datasheet
2Mb / 79P
   Analog-to-Digital Converter
AD9690-1000EBZ AD-AD9690-1000EBZ Datasheet
2Mb / 77P
   14-Bit, 1 GSPS/500 MSPS JESD204B, Analog-to-Digital Converter
AD9690-500EBZ AD-AD9690-500EBZ Datasheet
2Mb / 77P
   14-Bit, 1 GSPS/500 MSPS JESD204B, Analog-to-Digital Converter
AD9690BCPZ-1000 AD-AD9690BCPZ-1000 Datasheet
2Mb / 77P
   14-Bit, 1 GSPS/500 MSPS JESD204B, Analog-to-Digital Converter
More results

Similar Description - AD9698TQ

ManufacturerPart #DatasheetDescription
logo
Analog Devices
AD96685 AD-AD96685_01 Datasheet
100Kb / 8P
   Ultrafast Comparators
REV. D
AD96685 AD-AD96685_15 Datasheet
101Kb / 8P
   Ultrafast Comparators
REV. D
AD96687 AD-AD96687_15 Datasheet
101Kb / 8P
   Ultrafast Comparators
REV. D
AD96685 AD-AD96685 Datasheet
129Kb / 6P
   Ultrafast Comparators
REV. C
logo
Maxim Integrated Produc...
MXL1016 MAXIM-MXL1016 Datasheet
41Kb / 4P
   Ultra-Fast Precision TTL Comparators
logo
Analog Devices
ADCMP580 AD-ADCMP580_15 Datasheet
430Kb / 16P
   Ultrafast SiGe Voltage Comparators
REV. A
ADCMP581 AD-ADCMP581_15 Datasheet
430Kb / 16P
   Ultrafast SiGe Voltage Comparators
REV. A
ADCMP580 AD-ADCMP580_07 Datasheet
429Kb / 16P
   Ultrafast SiGe Voltage Comparators
Rev. A
ADCMP580 AD-ADCMP580_16 Datasheet
409Kb / 16P
   Ultrafast SiGe Voltage Comparators
ADCMP582 AD-ADCMP582_15 Datasheet
430Kb / 16P
   Ultrafast SiGe Voltage Comparators
REV. A
More results


Html Pages

1 2 3 4 5 6 7 8


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com