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FEATURES Fast: 2.5 ns Propagation Delay Low Power: 118 mW per Comparator Packages: DIP, SOIC, PLCC Power Supplies: +5 V, -5.2 V Logic Compatibility: ECL 50 ps Delay Dispersion APPLICATIONS High Speed Triggers High Speed Line Receivers Threshold Detectors Window Comparators Peak Detectors
Ultrafast Comparators AD96685/AD96687
AD96685 FUNCTIONAL BLOCK DIAGRAM
NONINVERTING INPUT INVERTING INPUT RL RL Q OUTPUT Q OUTPUT
LATCH ENABLE
VT
AD96687 FUNCTIONAL BLOCK DIAGRAM
NONINVERTING INPUT Q OUTPUT Q OUTPUT INVERTING INPUT LE LE VT RL RL Q OUTPUT Q OUTPUT RL RL LE INVERTING INPUT LE NONINVERTING INPUT
LATCH ENABLE
LATCH ENABLE
THE OUTPUTS ARE OPEN EMITTERS, REQUIRING EXTERNAL PULL-DOWN RESISTORS. THESE RESISTORS MAY BE IN THE RANGE OF 50 -200 CONNECTED TO -2.0V, OR 200 -2000
GENERAL DESCRIPTION
The AD96685 and AD96687 are ultrafast voltage comparators. The AD96685 is a single comparator with 2.5 ns propagation delay; the AD96687 is an equally fast dual comparator. Both devices feature 50 ps propagation delay dispersion which is a particularly important characteristic of high-speed comparators. It is a measure of the difference in propagation delay under differing overdrive conditions. A fast, high precision differential input stage permits consistent propagation delay with a wide variety of signals in the commonmode range from -2.5 V to +5 V. Outputs are complementary digital signals fully compatible with ECL 10 K and 10 KH logic families. The outputs provide sufficient drive current to directly drive transmission lines terminated in 50 to -2 V. A level sensitive latch input which permits tracking, track-hold, or sample-hold modes of operation is included. The AD96685 is available in industrial -25C to +85C range in 16-pin SOIC. The AD96687 is available in industrial range -25C to +85C, in 16-pin DIP, SOIC, and 20-lead PLCC.
REV. D
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 (c) Analog Devices, Inc., 2001
AD96685/AD96687-SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (Positive Supply Voltage = 5.0 V; Negative Supply Voltage = -5.2 V, unless otherwise noted.)
Industrial Temperature Range -25 C to +85 C Parameter INPUT CHARACTERISTICS Input Offset Voltage Input Offset Drift Input Bias Current Input Offset Current Input Resistance Input Capacitance Input Voltage Ranges2 Common-Mode Rejection Ratio ENABLE INPUT Logic "1" Voltage Logic "0" Voltage Logic "1" Current Logic "0" Current DIGITAL OUTPUTS3 Logic "1" Voltage Logic "0" Voltage SWITCHING PERFORMANCES Propagation Delays4 Input to Output HIGH Input to Output LOW Latch Enable to Output HIGH Latch Enable to Output LOW Dispersions5 Latch Enable Minimum Pulsewidth Minimum Setup Time Minimum Hold Time POWER SUPPLY6 Positive Supply Current (+5.0 V) Negative Supply Current (-5.2 V) Power Supply Rejection Ratio7 Temp 25C Full Full 25C Full 25C Full 25C 25C Full Full Full Full Full Full Full Full Test Level I VI V I VI I VI V V VI VI VI VI VI VI VI VI Min AD96685BR Typ Max 1 20 7 0.1 200 2 -2.5 80 -1.1 -1.5 40 5 -1.1 -1.5 -1.1 -1.5 +5.0 90 -2.5 80 -1.1 -1.5 40 5 2 3 10 13 1.0 1.2 AD96687BQ/BP/BR Min Typ Max 1 20 7 0.1 200 2 +5.0 90 2 3 10 13 1.0 1.2 Unit mV mV V/C A A A A k pF V dB V V A A V V
25C 25C 25C 25C 25C 25C 25C 25C Full Full Full
IV IV IV IV V IV IV IV VI VI VI
2.5 2.5 2.5 2.5 50 2.0 0.5 0.5 8 15 70
3.5 3.5 3.5 3.5 3.0 1.0 1.0 9 18 60
2.5 2.5 2.5 2.5 50 2.0 0.5 0.5 15 31 70
3.5 3.5 3.5 3.5 3.0 1.0 1.0 18 36
ns ns ns ns ps ns ns ns mA mA dB
60
NOTES 1 RS = 100 . 2 Input Voltage Range can be extended to -3.3 V if -VS = -6.0 V. 3 Outputs terminated through 50 to -2.0 V. 4 Propagation delays measured with 100 mV pulse (10 mV overdrive) to 50% transition point of the output. 5 Change in propagation delay from 100 mV to 1 V input overdrive. 6 Supply voltages should remain stable within 5% for normal operation. 7 Measured at 5% of +VS and -VS. Specifications subject to change without notice.
LATCH ENABLE
COMPARE LATCH
50%
tS tH
VDD VIN
tS tH tPD
- Minimum Setup Time - Minimum Hold Time - Input to Output Delay
DIFFERENTIAL INPUT VOLTAGE
tPW(E)
VOS
Q
tPD
tPD(E)
50%
tPD(E) - LATCH ENABLE to Output Delay tPW(E) - Minimum LATCH ENABLE Pulsewidth
VOS - Input Offset Voltage - Overdrive Voltage
Q
50%
VOD
Figure 1. System Timing Diagram
-2-
REV. D
AD96685/AD96687
ABSOLUTE MAXIMUM RATINGS 1 EXPLANATION OF TEST LEVELS
Positive Supply Voltage (+VS) . . . . . . . . . . . . . . . . . . . . . 6.5 V Negative Supply Voltage (-VS) . . . . . . . . . . . . . . . . . . . -6.5 V Input Voltage Range2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . 5.5 V Latch Enable Voltage . . . . . . . . . . . . . . . . . . . . . . . . -VS to 0 V Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 mA Operating Temperature Range3 AD96685BR/AD96687BQ/BR/BP . . . . . . . -25C to +85C Storage Temperature Range . . . . . . . . . . . . -55C to +150C Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 175C Lead Soldering Temperature (10 sec) . . . . . . . . . . . . . . 300C
NOTES 1 Absolute maximum ratings are limiting values, may be applied individually, and beyond which serviceability of the circuit may be impaired. Functional operation under any of these conditions is not necessarily implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 Under no circumstances should the input voltages exceed the supply voltages. 3 Typical thermal impedances . . . AD96685 SOIC qJA = 170C/W; qJC = 60C/W AD96687 Ceramic qJA = 115C/W; qJC = 57C/W AD96687 SOIC qJA = 92C/W; qJC = 47C/W AD96687 PLCC qJA = 81C/W; qJC = 45C/W
Test Level I - 100% production tested. II - 100% production tested at 25C, and sample tested at specified temperatures. III - Sample tested only. IV - Parameter is guaranteed by design and characterization testing. V - Parameter is a typical value only. VI - All devices are 100% production tested at 25C; 100% production tested at temperature extremes for extended temperature devices; sample tested at temperature extremes for commercial/industrial devices.
FUNCTIONAL DESCRIPTION
Pin Name +VS NONINVERTING INPUT INVERTING INPUT LATCH ENABLE
Description Positive supply terminal, nominally 5.0 V. Noninverting analog input of the differential input stage. The NONINVERTING INPUT must be driven in conjunction with the INVERTING INPUT. Inverting analog input of the differential input stage. The INVERTING INPUT must be driven in conjunction with the NONINVERTING INPUT. In the "compare" mode (logic HIGH), the output will track changes at the input of the comparator. In the "latch" mode (logic LOW), the output will reflect the input state just prior to the comparator being placed in the "latch" mode. LATCH ENABLE must be driven in conjunction with LATCH ENABLE for the AD96687. In the "compare" mode (logic LOW), the output will track changes at the input of the comparator. In the "latch" mode (logic HIGH), the output will reflect the input state just prior to the comparator being placed in the "latch" mode. LATCH ENABLE must be driven in conjunction with LATCH ENABLE for the AD96687. Negative supply terminal, nominally -5.2 V. One of two complementary outputs. Q will be at logic HIGH if the analog voltage at the NONINVERTING INPUT is greater than the analog voltage at the INVERTING INPUT (provided the comparator is in the "compare" mode). See LATCH ENABLE and LATCH ENABLE (AD96687 only) for additional information. One of two complementary outputs. Q will be at logic LOW if the analog voltage at the NONINVERTING INPUT is greater than the analog voltage at the INVERTING INPUT (provided the comparator is in the "compare" mode). See LATCH ENABLE and LATCH ENABLE (AD96687 only) for additional information. One of two grounds, but primarily associated with the digital ground. Both grounds should be connected together near the comparator. One of two grounds, but primarily associated with the analog ground. Both grounds should be connected together near the comparator.
LATCH ENABLE
-VS Q
Q
GROUND 1 GROUND 2
REV. D
-3-
AD96685/AD96687
PIN CONFIGURATIONS AD96685BR
GROUND 1 1 VS+ NONINVERTING INPUT INVERTING INPUT NC
2 3 4 16 GROUND 2 15 NC 14 NC
AD96687BP
Q OUTPUT Q OUTPUT Q OUTPUT Q OUTPUT
AD96687BQ/BR
Q OUTPUT 1 Q OUTPUT GROUND
18 17
2 3 4 16 Q OUTPUT 15 Q OUTPUT 14 GROUND
3
2
NC
1
20
19
AD96685
TOP VIEW
13 NC
5 (Not to Scale) 12 Q OUTPUT 11 Q OUTPUT 10 NC 9
LATCH ENABLE 6 NC 7 VS- 8
NC
GROUND LATCH ENABLE NC LATCH ENABLE VS-
4 5 6 7 8 9 10 11 12 13
AD96687
TOP VIEW (Not to Scale)
16 15 14
GROUND LATCH ENABLE NC LATCH ENABLE VS+
LATCH ENABLE LATCH ENABLE
AD96687
TOP VIEW
13 LATCH ENABLE
5 (Not to Scale) 12 LATCH ENABLE 11 VS+ 10 INVERTING INPUT 9
VS- 6 INVERTING INPUT 7 NONINVERTING 8 INPUT
NONINVERTING INPUT
NC = NO CONNECT
NC = NO CONNECT
ORDERING GUIDE
Model AD96685BR AD96687BP AD96687BQ AD96687BR AD96687BR-REEL
Type Single Dual Dual Dual Dual
Temperature Range -25C to +85C -25C to +85C -25C to +85C -25C to +85C -25C to +85C
INVERTING INPUT NONINVERTING INPUT NC NONINVERTING INPUT INVERTING INPUT
Description 16-Pin SOIC, Industrial 20-Pin PLCC, Industrial 16-Pin DIP, Industrial 16-Pin SOIC, Industrial 16-Pin SOIC, Industrial
Package Options R-16A P-20A Q-16 R-16A R-16A
CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD96685/AD96687 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
-4-
REV. D
Typical Performance Characteristics-AD96685/AD96687
APPLICATIONS INFORMATION
The AD96685/AD96687 comparators are very high speed devices. Consequently, high speed design techniques must be employed to achieve the best performance. The most critical aspect of any AD96685/AD96687 design is the use of a low impedance ground plane. Another area of particular importance is power supply decoupling. Normally, both power supply connections should be separately decoupled to ground through 0.1 F ceramic and 0.001 F mica capacitors. The basic design of comparator circuits makes the negative supply somewhat more sensitive to variations. As a result, more attention should be placed on ensuring a "clean" negative supply. The LATCH ENABLE input is active LOW (latched). If the latching function is not used, the LATCH ENABLE input should be grounded (ground is an ECL logic HIGH). The LATCH ENABLE input of the AD96687 should be tied to -2.0 V or left "floating," to disable the latching function. An alternate use of the LATCH ENABLE input is as a hysteresis control input. By varying the voltage at the LATCH ENABLE input for the AD96685 and the differential voltage between both latch inputs for the AD96687, small variations in the hysteresis can be achieved.
Occasionally, one of the two comparator stages within the AD96687 will not be used. The inputs of the unused comparator should not be allowed to "float." The high internal gain may cause the output to oscillate (possibly affecting the other comparator which is being used) unless the output is forced into a fixed state. This is easily accomplished by ensuring that the two inputs are at least one diode drop apart, while also grounding the LATCH ENABLE input. The best performance will be achieved with the use of proper ECL terminations. The open-emitter outputs of the AD96685/ AD96687 are designed to be terminated through 50 resistors to -2.0 V, or any other equivalent ECL termination. If high speed ECL signals must be routed more than a few centimeters, MicroStrip or StripLine techniques may be required to ensure proper transition times and prevent output ringing. The AD96685/AD96687 have been specifically designed to reduce propagation delay dispersion over an input overdrive range of 100 mV to 1 V. Propagation delay dispersion is the change in propagation delay which results from a change in the degree of overdrive (how far the switching point is exceeded by the input). The overall result is a higher degree of timing accuracy since the AD96685/AD96687 are far less sensitive to input variations than most comparator designs.
REV. D
-5-
AD96685/AD96687 Typical Applications
+VREF
AD96685/ AD96687
VIN OUTPUTS VREF 50 50 50 50 50
-VREF VIN
50
AD96685/ AD96687
50
OUTPUT 50 50 50 50
LATCH ENABLE INPUT
-2V
-2V
Figure 2. High Speed Sampling Circuit
Figure 3. High Speed Window Comparator
-6-
REV. D
AD96685/AD96687
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
16-Lead Ceramic DIP
0.005 (0.13) MIN
16
16-Lead SOIC
0.394 (10.00) 0.385 (9.78) 0.158 (4.00) 0.150 (3.80)
16 1 9 8
0.098 (2.49) MAX
9
PIN 1
1 8
0.310 (7.87) 0.220 (5.59) 0.060 (1.52) 0.015 (0.38)
0.320 (8.13) 0.290 (7.37)
0.244 (6.20) 0.228 (5.80) 0.205 (5.20) 0.181 (4.60)
0.840 (21.34) MAX 0.200 (5.08) MAX
0.150 (3.81) 0.200 (5.08) MIN 0.125 (3.18) SEATING 0.023 (0.58) 0.100 0.070 (1.78) PLANE 0.014 (0.36) (2.54) 0.030 (0.76) BSC
PIN 1 15 0 0.310 (7.87) 0.220 (5.58) 0.015 (0.38) 0.008 (0.20)
0.050 (1.27) BSC
0.069 (1.75) 0.053 (1.35)
0.010 (0.25) 0.004 (0.10)
0.018 (0.46) 0.014 (0.36)
SEATING 0.015 (0.38) PLANE 0.007 (0.18)
8 0
0.045 (1.15) 0.025 (0.50)
20-Lead PLCC
0.173 (4.39) 0.165 (4.19) 0.020 (0.51) MIN 0.035 (0.890) R 0.034 (0.864)
19
PIN 1 IDENTIFIER
0.045 (1.14) 0.042 (1.07) 0.045 (1.14) 0.042 (1.07)
3 4
18
TOP VIEW
(PINS DOWN) 8 14 9 13
0.050 (1.27) BSC
0.017 (0.432) 0.013 (0.330) 0.330 (8.38) 0.029 (0.737) 0.290 (7.37) 0.026 (0.660)
0.020 (0.50) MAX
0.353 (8.97) 0.350 (8.89) SQ 0.390 (9.91) SQ 0.385 (9.78)
0.025 (0.64) MIN 0.060 (1.53) MIN
Revision History
Location Data Sheet changed from REV. C to REV. D. Page
Edits to FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Edits to GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Edits to ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Edits to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Deleted DIE LAYOUT AND MECHANICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Edits to OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
REV. D
-7-
-8-
C00698-0-2/02(D)
PRINTED IN U.S.A.
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