AD ADCMP581BCP Ultrafast sige voltage comparator Datasheet

FEATURES
150 ps propagation delay
25 ps overdrive and slew rate dispersion
8 GHz equivalent input rise time bandwidth
100 ps minimum pulse width
35 ps typical output rise/fall
10 ps deterministic jitter(DJ)
200 fs random jitter (RJ)
−2 V to +3 V input range with +5 V/−5.2 V supplies
On-chip terminations at both input pinsl
Resistor-programmable hysteresis
Differential latch control
Power supply rejection > 70 dB
APPLICATIONS
Automatic test equipment (ATE)
High speed instrumentation
Pulse spectroscopy
Medical imaging and diagnostics
High speed line receivers
Threshold detection
Peak and zero-crossing detectors
High speed trigger circuitry
Clock and data signal restoration
GENERAL DESCRIPTION
The ADCMP580/ADCMP581/ADCMP582 are ultrafast voltage
comparators fabricated on Analog Devices, Inc.’s proprietary
XFCB3 Silicon Germanium (SiGe) bipolar process. The
ADCMP580 features CML output drivers; the ADCMP581
features reduced swing ECL (negative ECL) output drivers; and
the ADCMP582 features reduced-swing PECL (positive ECL)
output drivers.
FUNCTIONAL BLOCK DIAGRAM
VTP TERMINATION
VP NONINVERTING
INPUT
VN INVERTING
INPUT
ADCMP580/
ADCMP581/
ADCMP582
Q OUTPUT
CML/ECL/
PECL
Q OUTPUT
VTN TERMINATION
LE INPUT
HYS
LE INPUT
04672-0-001
Preliminary Technical Data
Ultrafast SiGe
Voltage Comparator
ADCMP580/ADCMP581/ADCMP582
Figure 1.
The ±5 V power supplies enable a wide −2 V to +3 V input
range with logic levels referenced to the CML/NECL/PECL
outputs. The three inputs have 50 Ω on-chip termination
resistors with the optional capability to be left open (on an
individual pin basis) for applications requiring high impedance
input.
The CML output stage is designed to directly drive 400 mV into
50 Ω transmission lines terminated to ground. The NECL
output stages are designed to directly drive 400 mV into 50 Ω
terminated to −2 V. The PECL output stages are designed to
directly drive 400 mV into 50 Ω terminated to VCCO − 2 V. High
speed latch and programmable hysteresis are also provided. The
differential latch input controls are also 50 Ω terminated to an
independent VTT pin to interface to either CML or ECL or to
PECL logic.
The ADCMP580/ADCMP581/ADCMP582 are available in a
16-lead LFCSP package.
The three comparators offer 150 ps propagation delay and 100
ps minimum pulse width for 10 Gbps operation with 200 fs
random jitter (RJ). Overdrive and slew rate dispersion is
typically less than 25 ps.
Rev. PrA
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.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
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Fax: 781.326.8703
2003 Analog Devices, Inc. All rights reserved.
©©2004
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
TABLE OF CONTENTS
Electrical Characteristics ................................................................. 3
Using/Disabling the Latch Feature..............................................9
Absolute Maximum Ratings............................................................ 5
Optimizing High Speed Performance ..................................... 10
ESD Caution.................................................................................. 5
Comparator Propagation Delay Dispersion ........................... 10
Thermal Considerations.............................................................. 5
Comparator Hysteresis .............................................................. 11
Pin Configuration and Function Descriptions............................. 6
Minimum Input Slew Rate Requirement ................................ 11
Typical Performance Characteristics ............................................. 7
Typical Application Circuits.......................................................... 12
Application Information.................................................................. 9
Timing Information ....................................................................... 13
Power/Ground Layout and Bypassing ....................................... 9
Outline Dimensions ....................................................................... 14
ADCMP58x Family of Output Stages ....................................... 9
Ordering Guide .......................................................................... 14
REVISION HISTORY
6/04—Revision PrA
Rev. PrA | Page 2 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
ELECTRICAL CHARACTERISTICS
VCCI = +5.0 V, VEE = −5.0 V, VCCO = +3.3 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter
DC INPUT CHARACTERISTICS
Input Voltage Range
Input Differential Range
Input Offset Voltage
Offset Voltage Tempco
Input Bias Current
Input Bias Current Tempco
Input Offset Current
Input Capacitance
Input Resistance
Input Resistance, Differential Mode
Input Resistance, Common Mode
Active Gain
Common-Mode Rejection
Hysteresis
LATCH ENABLE CHARACTERISTICS
ADCMP580 (CML)
Latch Enable Input Range
Latch Enable Input Differential
Latch Setup Time
Latch Hold Time
ADCMP581 (NECL)
Latch Enable Input Range
Latch Enable Input Differential
Latch Setup Time
Latch Hold Time
ADCMP582 (PECL)
Latch Enable Input Range
Latch Enable Input Differential
Latch Setup Time
Latch Hold Time
Latch Enable Input Impedance
Latch to Output Delay
Latch Minimum Pulse Width
DC OUTPUT CHARACTERISTICS
ADCMP580 (CML)
Output Impedance
Output Voltage High Level
Output Voltage Low Level
Output Voltage Differential
Temperature Coefficient, VOH
Temperature Coefficient, VOL
ADCMP581 (NECL)
Output Voltage High Level
Output Voltage Low Level
Output Voltage Differential
Symbol
Condition
VP, VN
VOS
∆VOS/dT
IP, IN
Min
−2.0
−2.0
−5.0
Open termination
CP, CN
47.5
Open termination
Open termination
AV
CMRR
VCM = −2.0 V to +3.0 V
RHYS = ∞
−0.8
0.2
tS
tH
VOD = 100 mV
VOD = 100 mV
−1.8
0.2
tS
tH
VOD = 100 mV
VOD = 100 mV
VCCO − 1.8
0.2
tS
tH
VOD = 100 mV
VOD = 100 mV
tPLOH, tPLOL
tPL
VOD = 100 mV
VOD = 100 mV
47.5
ZOUT
VOH
VOL
∆VOH/dT
∆VOL/dT
VOH
VOL
50 Ω to GND
50 Ω to GND
50 Ω to GND
50 Ω to GND
50 Ω GND
50 Ω to −2.0 V
50 Ω to −2.0 V
50 Ω to −2.0 V
Rev. PrA | Page 3 of 16
Typ
±2.0
10.0
15.0
50.0
2.0
TBD
50
50
500
48
50
±1
0.4
60
0
0.4
25
0
0.4
5
0
50.0
150
100
Max
Unit
+3.0
+2.0
+5.0
V
V
mV
µV/°C
µA
nA/°C
µA
pF
Ω
kΩ
kΩ
dB
dB
mV
30.0
5.0
52.5
0
0.5
V
V
ps
ps
+0.8
0.5
V
V
ps
ps
VCCO − 0.8
0.5
V
V
ps
ps
ps
ps
ps
52.5
47.5
−0.10
VOH − 0.45
350
50
−0.05
VOH − 0.40
400
TBD
TBD
52.5
0.00
VOH − 0.35
450
Ω
V
V
mV
mV/°C
mV/°C
−0.90
VOH − 0.45
350
−0.80
VOH − 0.40
400
−0.70
VOH − 0.35
450
V
V
mV
Preliminary Technical Data
Parameter
ADCMP582 (PECL)
Output Voltage High Level
Output Voltage Low Level
Output Voltage Differential
AC PERFORMANCE
Propagation Delay
Propagation Delay
Propagation Delay Tempco
Prop Delay Skew—Rising Transition
to Falling Transition
Overdrive Dispersion
Symbol
Condition
Min
Typ
Max
Unit
VOH
VOL
50 Ω to VCCO − 2.0 V
50 Ω to VCCO − 2.0 V
50 Ω to VCCO − 2.0 V
VCCO − 0.9
VOH − 0.45
350
VCCO − 0.80
VOH − 0.40
400
VCCO− 0.70
VOH − 0.35
450
V
V
mV
tPD
VOD = 200 mV
VOD = 20 mV
∆tPD/dT
VOD = 200 mV, 5 V/ns
Slew Rate Dispersion
Pulse Width Dispersion
Duty Cycle Dispersion
Common-Mode Dispersion
Equivalent Input Bandwidth1
BWEQ
Toggle Rate
Deterministic Jitter
DJ
Deterministic Jitter
DJ
RMS Random Jitter
Minimum Pulse Width
Minimum Pulse Width
Rise Time
Fall Time
POWER SUPPLY
Positive Supply Voltage
Negative Supply Voltage
Logic Supply Voltage
ADCMP580 (CML)
Positive Supply Current
Negative Supply Current
Power Dissipation
ADCMP581 (NECL)
Positive Supply Current
Negative Supply Current
Power Dissipation
ADCMP582 (PECL)
Positive Supply Current
1
ADCMP580/ADCMP581/ADCMP582
RJ
PWMIN
PWMIN
tR
tF
50 mV < VOD < 1.0 V
5 mV < VOD < 1.0 V
2 V/ns to 10 V/ns
100 ps to 5 ns
1.0 V/ns, VCM = 0.0 V
1.0 V/ns, VCM = 2.0 V
VOD = 0.4V , −2 V < VCM < 3 V
0.0 V to 400 mV input
tR = tF = 25 ps, 20/80
>50% Output Swing
VOD = 200 mV, 5 V/ns
PRBS31 − 1 NRZ, 4 Gbps
VOD = 200 mV, 5 V/ns
PRBS31 − 1 NRZ, 10 Gbps
VOD = 200 mV, 5 V/ns, 1.25 GHz
tPD/PW < 5 ps
tPD/PW < 10 ps
20/80
20/80
VCCI
VEE
VCCO
+4.5
−5.5
+4.5/+2.0
150
165
0.5
10
ps
ps
ps/°C
ps
10
15
25
5
10
5
5
8.0
ps
ps
ps
ps
ps
ps
ps/V
GHz
12.5
10
Gbps
ps
TBD
ps
0.2
100
80
35
35
ps
ps
ps
ps
ps
+5.0
−5.0
+5.0/+2.5
+5.5
−4.5
+5.5/+3.0
V
V
V
IVCCI
IVEE
PD
VCCI = +5.0 V, 50 Ω to Ground
VEE = −5.0 V, 50 Ω to Ground
50 Ω to Ground
6
43
244
8
50
260
mA
mA
mW
IVCCI
IVEE
PD
VCCI = +5.0 V, 50 Ω to −2 V
VEE = −5.0 V, 50 Ω to −2 V
50 Ω to −2 V
6
28
218
8
35
240
mA
mA
mW
IVCCI + IVCCO
47
55
mA
28
253
70
35
275
mA
mW
dB
75
70
Negative Supply Current
Power Dissipation
Power Supply Rejection (VCCI)
IVEE
PD
PSRVCCI
VCCI = +5.0 V, VCCO = +5.0 V
50 Ω to VCCO − 2 V
VEE = −5.0 V, 50 Ω to VCCO − 2 V
50 Ω to VCCO − 2 V
VCCI=5.0 V + 5%
Power Supply Rejection (VEE)
Power Supply Rejection (VCCO)
PSRVEE
PSRVCCO
VEE=-5.0 V + 5%
VCCO=3.3 V + 5%
dB
dB
Equivalent Input Bandwidth assumes a simple first-order input response and is calculated with the following formula: BWEQ = 0.22/√(trCOMP2 – trIN2), where trIN
is the 20/80 transition time of a quasi-Gaussian input edge applied to the comparator input and trCOMP is the effective transition time digitized by the
comparator.
Rev. PrA | Page 4 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
SUPPLY VOLTAGES
Positive Supply Voltage
(VCCI to GND)
Negative Supply Voltage
(VEE to GND)
Logic Supply Voltage
(VCCO to GND)
INPUT VOLTAGES
Input Voltage
Differential Input Voltage
Input Voltage, Latch Enable
HYSTERESIS CONTROL PIN
Applied Voltage (HYS to VEE)
Maximum Input/Output Current
OUTPUT CURRENT
ADCMP580 (CML)
ADCMP581 (NECL)
ADCMP582 (PECL)
TEMPERATURE
Operating Temperature, Ambient
Operating Temperature, Junction
Storage Temperature Range
THERMAL CONSIDERATIONS
Rating
−0.5 V to +6.0 V
–6.0 V to +0.5 V
−0.5 V to +6.0 V
−3.0 V to +4.0 V
−2.5 V to +2.5 V
−2.5 V to +5.5 V
The ADCMP580/ADCMP581/ADCMP582 LFCSP 16-lead
package option has a θJA (junction to ambient thermal
resistance) of 70°C/W in still air.
Stress above those listed under Absolute Maximum Ratings may
cause permanent damage to the device. This is a stress rating
only and functional operation of the device at these or any other
conditions above those indicated in the operational sections of
this specification is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability.
−5.5 V to +0.5 V
1 mA
−25 mA
−40 mA
−40 mA
−40°C to +85°C
125°C
−65°C to +150°C
ESD 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 this product 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.
Rev. PrA | Page 5 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
VTN 4
9 GND
Figure 3. ADCMP581 Pin Configuration
13 VEE
14 HYS
TOP VIEW
(Not to Scale)
12 VCCO
11 Q
10 Q
9 VCCO
04672-0-029
VN 3
ADCMP582
VTT 8
10 Q
15 GND
16 VCCI
13 VEE
VP 2
LE 7
04672-0-002
Figure 2. ADCMP580 Pin Configuration
VCCI 5
VTN 4
9 GND
TOP VIEW
(Not to Scale)
11 Q
PIN 1
INDICATOR
LE 6
VN 3
VTP 1
VCCI 5
10 Q
ADCMP581
12 GND
04672-0-028
VP 2
LE 7
11 Q
PIN 1
INDICATOR
VTT 8
VTP 1
14 HYS
16 VCCI
15 GND
12 GND
LE 6
13 VEE
VTT 8
LE 7
TOP VIEW
(Not to Scale)
VCCI 5
VTN 4
ADCMP580
LE 6
VN 3
14 HYS
PIN 1
INDICATOR
VTP 1
VP 2
15 GND
16 VCCI
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 4. ADCMP582 Pin Configuration
Table 3. Pin Descriptions
Pin No.
1
2
3
4
5, 16
6
Mnemonic
VTP
VP
VN
VTN
VCCI
LE
7
LE
8
VTT
9, 12
GND/VCCO
10
Q
11
Q
13
14
VEE
HYS
15
Heatsink
GND
N/C
Description
Termination Resistor Return Pin for VP Input.
Noninverting Analog Input.
Inverting Analog Input.
Termination Resistor Return Pin for VN Input.
Positive Supply Voltage.
Latch Enable Input Pin, Inverting Side. In compare mode (LE = low), the output tracks changes at the input of the
comparator. In latch mode (LE = high), the output reflects the input state just prior to the comparator’s being
placed into latch mode. LE must be driven in compliment with LE.
Latch Enable Input Pin, Noninverting Side. In compare mode (LE = high), the output tracks changes at the input of
the comparator. In latch mode (LE = low), the output reflects the input state just prior to the comparator’s being
placed into latch mode. LE must be driven in compliment with LE.
Termination Return Pin for the LE/LE Input Pins.
For the ADCMP580 (CML output stage), this pin should be connected to the GND ground.
For the ADCMP581 (ECL output stage), this pin should be connected to the –2 V termination potential.
For the ADCMP582 (PECL output stage), this pin should be connected to the VCCO – 2 V termination potential.
Digital Ground Pin/Positive Logic Power Supply Terminal.
For the ADCMP580/ADCMP581, this pin should be connected to the GND pin.
For the ADCMP582, this pin should be connected to the positive logic power VCCO supply.
Inverting Output. Q is logic low if the analog voltage at the noninverting input, VP, is greater than the analog
voltage at the inverting input, VN, provided that the comparator is in compare mode. See the LE/LE descriptions
(Pins 6 to 7) for more information.
Noninverting Output. Q is logic high if the analog voltage at the noninverting input, VP, is greater than the analog
voltage at the inverting input, VN, provided that the comparator is in compare mode. See the LE/LE descriptions
(Pins 6 to 7) for more information.
Negative Power Supply.
Hysteresis Control. Leave this pin disconnected for zero hysteresis. Connect this pin to the VEE supply with a
suitably sized resistor to add the desired amount of hysteresis. Refer to Figure 9 for proper sizing of the HYS
hysteresis control resistor.
Analog Ground.
The metallic back surface of the package is not electrically connected to any part of the circuit. It can be left
floating for optimal electrical isolation between the package handle and the substrate of the die. It can also be
soldered to the application board if improved thermal and/or mechanical stability is desired.
Rev. PrA | Page 6 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
TYPICAL PERFORMANCE CHARACTERISTICS
VCCI = +5.0 V, VEE = −5.0 V, VCCO = +3.3 V, TA = 25°C, unless otherwise noted.
Figure 5. Propagation Delay vs. Input Overdrive
Figure 8. Rise/Fall Time vs. Temperature
Figure 6. Propagation Delay vs. Input Common Mode
Figure 9. Hysteresis vs. RHYS Control Resistor
Figure 7. Propagation Delay vs. Temperature
Figure 10. Input Bias Current vs. Input Differential
Rev. PrA | Page 7 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
Figure 11. Input Bias Current vs. Temperature
Figure 13. Output Levels vs. Temperature
Figure 12. Input Offset Voltages vs. Temperature
Rev. PrA | Page 8 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
APPLICATION INFORMATION
POWER/GROUND LAYOUT AND BYPASSING
GND
The ADCMP58x family of comparators is designed for very
high speed applications. Consequently, high speed design
techniques must be used to achieve the specified performance.
It is critically important to use low impedance supply planes,
particularly for the negative supply (VEE), the output supply
plane (VCCO) and the ground plane (GND). Individual supply
planes are recommended as part of a multilayer board.
Providing the lowest inductance return path for the switching
currents ensures the best possible performance in the target
application.
50Ω
Q
Q
VEE
It is also important to adequately bypass the input and output
supplies. A 1 µF electrolytic bypass capacitor should be placed
within several inches of each power supply pin to ground. In
addition, multiple high quality 0.1µF bypass capacitors should
be placed as close as possible to each of the VEE, VCCI, and VCCO
supply pins and should be connected to the GND plane with
redundant vias. High frequency bypass capacitors should be
carefully selected for minimum inductance and ESR. Parasitic
layout inductance should be strictly avoided to maximize the
effectiveness of the bypass at high frequencies.
04672-0-014
16mA
Figure 14. Simplified Schematic Diagram of ADCMP580 CML Output Stage
GND
Q
ADCMP58x FAMILY OF OUTPUT STAGES
VEE
04672-0-015
Q
Specified propagation delay dispersion performance can be
achieved by using proper transmission line terminations. The
outputs of the ADCMP580 comparators are designed to directly
drive 400 mV into 50 Ω cable or microstrip/stripline
transmission lines terminated with 50 Ω referenced to the GND
return. The CML output stage is shown in the simplified
schematic diagram in Figure 14. The outputs are each backterminated with 50 Ω for best transmission line matching. The
outputs of the ADCMP581/ADCMP582 are illustrated in
Figure 15 and should be terminated to −2 V for ECL outputs of
ADCMP581 and VCCO − 2 V for PECL outputs of
ADCMP582. As an alternative, Thevenin equivalent
termination networks may also be used. If high speed CML
signals must be routed more than a centimeter, then either
microstrip or stripline techniques is required to ensure proper
transition times and to prevent excessive output ringing and
pulse-width-dependant propagation delay dispersion.
Figure 15. Simplified Schematic Diagram of
the ADCMP581/ADCMP582 ECL Output Stage
USING/DISABLING THE LATCH FEATURE
The latch inputs (LE/LE) are active low for latch mode, and are
internally terminated with 50 Ω resistors to the VTT pin. When
using the ADCMP580, VTT should be connected to ground.
When using the ADCMP581, VTT should be connected to −2 V.
When using the ADCMP582, VTT should be connected
externally to VCCO − 2 V, preferably to its own low inductance
plane.
When using the ADCMP580/ADCMP582, the latch function
can be disabled by connecting the LE pin to VEE with an
external pull-down resistor and leaving the LE pin unconnected.
To prevent excessive power dissipation, the resistor should be
1.5 kΩ. When using the ADCMP581 comparators, the latch can
be disabled by connecting the LE pin to GND with an external
450 Ω resistor, and leaving the LE pin disconnected.
Rev. PrA | Page 9 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
OPTIMIZING HIGH SPEED PERFORMANCE
As with any high speed comparator, proper design and layout
techniques are essential to obtaining the specified performance.
Stray capacitance, inductance, inductive power and ground
impedances, or other layout issues can severely limit
performance and can cause oscillation. Discontinuities along
input and output transmission lines can also severely limit the
specified pulse width dispersion performance.
For applications working in a 50 Ω environment, input and
output matching have a significant impact on data-dependant
(or deterministic) jitter (DJ) and pulse width dispersion
performance. The ADCMP58x family of comparators provides
internal 50 Ω termination resistors for both VP and VN inputs.
The return side for each termination is pinned out separately
with the VTP and VTN pins, respectively. If the a 50 Ω termination
is desired at one or both of the VP/VN inputs, the VTP and VTN
pins can be connected (or disconnected) to (from) the desired
termination potential as appropriate. The termination potential
should be carefully bypassed using ceramic capacitors as
discussed previously to prevent undesired aberrations on the
input signal due to parasitic inductance in the termination
return path. If a 50 Ω termination is not desired, either one or
both of the VTP/VTN termination pins can be left disconnected.
In this case, the open pins should be left floating with no
external pull downs or bypassing capacitors.
COMPARATOR PROPAGATION
DELAY DISPERSION
The ADCMP58x family of comparators has been specifically
designed to reduce propagation delay dispersion over a wide
input overdrive range of 5 mV to 500 mV. Propagation delay
dispersion is a change in propagation delays, which results from
a change in the degree of overdrive or slew rate (how far or fast
the input signal exceeds the switching threshold). The overall
result is a higher degree of timing accuracy.
Propagation delay dispersion is a specification which becomes
important in critical timing applications such as data
communication, automatic test and measurement,
instrumentation, and event driven applications such as pulse
spectroscopy, nuclear instrumentation, and medical imaging.
Dispersion is defined as the variation in the overall propagation
delay as the input overdrive conditions are changed (Figure 16
and Figure 17). For the ADCMP58x family of comparators,
dispersion is typically < 25 ps since the overdrive varies from
5 mV to 500 mV, and the input slew rate varies from 1 V/ns to
10 V/ns. This specification applies for both positive and
negative signals since the ADCMP58x family of comparators
has almost equal delays for positive- and negative-going inputs.
500mV OVERDRIVE
INPUT VOLTAGE
5mV OVERDRIVE
DISPERSION
Q/Q OUTPUT
04672-0-016
VN ± VOS
Figure 16. Propagation Delay—Overdrive Dispersion
INPUT VOLTAGE
1V/ns
VN ± VOS
10V/ns
DISPERSION
Q/Q OUTPUT
04672-0-017
For applications that require high speed operation, but do not
have on-chip 50 Ω termination resistors, some reflections
should be expected because the comparator inputs can no
longer provide matched impedance to the input trace leading
up to the device. It then becomes important to back-match the
drive source impedance to the input transmission path leading
to the input to minimize multiple reflections. For applications in
which the comparator is very close to the driving signal source,
the source impedance should be minimized. High source
impedance in combination with parasitic input capacitance of
the comparator could cause undesirable degradation in
bandwidth at the input, thus degrading the overall response.
Although the ADCMP58x family of comparators has been
designed to minimize input capacitance, some parasitic
capacitance is inevitable. It is therefore recommended that the
drive source impedance should be no more than 50 Ω for best
high speed performance.
Figure 17. Propagation Delay—Slew Rate Dispersion
Rev. PrA | Page 10 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
–VH
2
COMPARATOR HYSTERESIS
Adding hysteresis to a comparator is often desirable in a noisy
environment or when the differential inputs are very small or
slow moving. The transfer function for a comparator with
hysteresis is shown in Figure 18. If the input voltage approaches
the threshold from the negative direction, the comparator
switches from a low to a high when the input crosses +VH/2.
The new switching threshold becomes −VH/2. The comparator
remains in the high state until the threshold −VH/2 is crossed
coming from the positive direction. In this manner, noise
centered on 0 V input does not cause the comparator to switch
states unless it exceeds the region bounded by ±VH/2.
INPUT
1
OUTPUT
Figure 19 illustrates the amount of applied hysteresis as a
function of external resistor value. The advantage of applying
hysteresis in this manner is improved accuracy, stability, and
reduced component count. An external bypass capacitor is not
required on the HYS pin because it would likely degrade the
jitter performance of the device.
04672-0-018
0
Figure 18. Comparator Hysteresis Transfer Function of the
ADCMP580/ADCMP581
The customary technique for introducing hysteresis into a
comparator uses positive feedback from the output back to the
input. A limitation of this approach is that the amount of
hysteresis varies with the output logic levels, resulting in
hysteresis that is not symmetric about the threshold. The
external feedback network can also introduce significant
parasitics that will reduce high speed performance, and can
even reduce overall stability in some cases.
The ADCMP58x family of comparators offers a programmable
hysteresis feature that can significantly improve the accuracy
and stability of the desired hysteresis. By connecting an external
pull-down resistor from the HYS pin to VEE, a variable amount
of hysteresis can be applied. Leaving the HYS pin disconnected
disables the feature and hysteresis is then less than 1 mV as
specified. The maximum range of hysteresis that can be applied
by using this method is approximately ±25 mV.
+VH
2
0V
Figure 19. Comparator Hysteresis vs. RHYS Control Resistor
MINIMUM INPUT SLEW RATE REQUIREMENT
As with all high speed comparators, a minimum slew rate must
be met to ensure that the device does not oscillate when the
input signal crosses the threshold. This oscillation is due in part
to the high input bandwidth of the comparator and the
feedback parasitics inherent in the package. Analog Devices
recommends a minimum slew rate of 50 V/µs to ensure a clean
output transition from the ADCMP58x family of comparators
unless hysteresis is programmed as discussed previously.
Rev. PrA | Page 11 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
TYPICAL APPLICATION CIRCUITS
GND
GND
VTP
VIN
50Ω
50Ω
75Ω
VP
VN
75Ω
Q
ADCMP580
100Ω
ADCMP580
Q
VTN
100Ω
LATCH
INPUTS
Figure 20. Zero-Crossing Detector with CML Outputs
04672-0-024
04672-0-021
50Ω
50Ω
LATCH
INPUTS
Figure 21. Interfacing CML to a 50 Ω Ground-Terminated Instrument
GND
VTP
50Ω
50Ω
VP
VP
VN
VN
Q
ADCMP580
Q
VP
VN
ADCMP580
VTN
LATCH
INPUTS
Figure 22. LVDS to a 50 Ω Back-Terminated (RS)ECL Receiver
50Ω
50Ω
04672-0-025
04672-0-022
1.5kΩ
VEE
Figure 23. Disabling the Latch Feature
GND
50Ω
VTH
–
50Ω
Q
ADCMP580
ADCMP580
HYS
Q
04672-0-023
0Ω TO 5kΩ
LATCH
INPUTS
VEE
Figure 24. Comparator with –2 V to +3 V Input Range
50Ω
50Ω
04672-0-026
VIN
+
Figure 25. Adding Hysteresis Using the HYS Control
Rev. PrA | Page 12 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
TIMING INFORMATION
Figure 26 shows the ADCMP580/ADCMP581/ADCMP582 compare and latch timing relationships. Table 4 provides a definition of the
terms shown in the figure.
LATCH ENABLE
50%
LATCH ENABLE
tS
tPL
tH
DIFFERENTIAL
INPUT VOLTAGE
VN
VN ± VOS
VOD
tPDL
tPLOH
Q OUTPUT
50%
tF
tPDH
tPLOL
tR
04672-0-027
50%
Q OUTPUT
Figure 26. Comparator Timing Diagram
Table 4. Timing Descriptions
Symbol
tPDH
tPDL
tPLOH
tPLOL
tH
tPL
Timing
Input to output high
delay
Input to output low
delay
Latch enable to output
high delay
Latch enable to output
low delay
Minimum hold time
tS
Minimum latch enable
pulse width
Minimum setup time
tR
Output rise time
tF
Output fall time
VOD
Voltage overdrive
Description
Propagation delay measured from the time the input signal crosses the reference (± the input offset
voltage) to the 50% point of an output low-to-high transition.
Propagation delay measured from the time the input signal crosses the reference (± the input offset
voltage) to the 50% point of an output high-to-low transition.
Propagation delay measured from the 50% point of the Latch Enable signal low-to-high transition to
the 50% point of an output low-to-high transition.
Propagation delay measured from the 50% point of the Latch Enable signal low-to-high transition to
the 50% point of an output high-to-low transition.
Minimum time after the negative transition of the Latch Enable signal that the input signal must
remain unchanged to be acquired and held at the outputs.
Minimum time that the Latch Enable signal must be high to acquire an input signal change.
Minimum time before the negative transition of the Latch Enable signal that an input signal change
must be present to be acquired and held at the outputs.
Amount of time required to transition from a low to a high output as measured at the 20% and 80%
points.
Amount of time required to transition from a high to a low output as measured at the 20% and 80%
points.
Difference between the input voltages VP and VN.
Rev. PrA | Page 13 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
OUTLINE DIMENSIONS
3.00
BSC SQ
0.60 MAX
2.75
BSC SQ
TOP VIEW
0.80 MAX
0.65 TYP
12° MAX
SEATING
PLANE
16
1
1.65
1.50 SQ*
1.35
BOTTOM
VIEW
0.50
BSC
1.00
0.85
0.80
PIN 1 INDICATOR
13
12
0.45
PIN 1
INDICATOR
0.50
0.40
0.30
9
8
5
4
0.25 MIN
1.50 REF
0.05 MAX
0.02 NOM
0.30
0.23
0.18
0.20 REF
* COMPLIANT TO JEDEC STANDARDS MO-220-VEED-2
EXCEPT FOR EXPOSED PAD DIMENSION
Figure 27. 16-Lead Lead Frame Chip Scale Package [LFCSP]
(CP-16)
Dimensions shown in millimeters
ORDERING GUIDE
Model
ADCMP580BCP
ADCMP581BCP
ADCMP582BCP
Temperature Range
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
Package Description
LFCSP-16
LFCSP-16
LFCSP-16
Rev. PrA | Page 14 of 16
Package Option
CP-16
CP-16
CP-16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
NOTES
Rev. PrA | Page 15 of 16
Preliminary Technical Data
ADCMP580/ADCMP581/ADCMP582
NOTES
© 2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
PR04672-0-6/04(PrA)
Rev. PrA | Page 16 of 16