Datasheet AD8561AR, AD8561AN Datasheet (Analog Devices)

Ultrafast 7 ns

ⴙIN
ⴚIN

Vⴚ

OUT
GND

LATCH

OUT

1

45

8

AD8561

Vⴙ

a

FEATURES
7 ns Propagation Delay at 5 V
Single Supply Operation: 3 V to 10 V
Low Power
Latch Function
TSSOP Packages

APPLICATIONS
High Speed Timing
Clock Recovery and Clock Distribution
Line Receivers
Digital Communications
Phase Detectors
High Speed Sampling
Read Channel Detection
PCMCIA Cards
Upgrade for LT1016 Designs

GENERAL DESCRIPTION

The AD8561 is a single 7 ns comparator with separate input and
output sections. Separate supplies enable the input stage to be

operated from ±5 V dual supplies and +5 V single supplies.

Fast 7 ns propagation delay makes the AD8561 a good choice
for timing circuits and line receivers. Propagation delays for
rising and falling signals are closely matched and track over
temperature. This matched delay makes the AD8561 a good
choice for clock recovery, since the duty cycle of the output will
match the duty cycle of the input.

The AD8561 has the same pinout as the LT1016, with lower
supply current and a wider common-mode input range, which
includes the negative supply rail.

The AD8561 is specified over the industrial (–40°C to +85°C)

temperature range. The AD8561 is available in both the 8-lead
plastic DIP, 8-lead TSSOP or narrow SO-8 surface mount
packages.

Single Supply Comparator

PIN CONFIGURATIONS

8-Lead Narrow Body SO

(SO-8)

ⴙIN
ⴚIN

Vⴙ

Vⴚ

AD8561

OUT

OUT
GND

LATCH

8-Lead TSSOP

(RU-8)

AD8561

8-Lead Plastic DIP

(N-8)

8

7

6

5

ⴙIN
ⴚIN

Vⴙ

1

2

3

4

AD8561

OUT

OUT
GND
LATCHVⴚ

REV. 0

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
which 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: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 1998

AD8561–SPECIFICATIONS

ELECTRICAL SPECIFICATIONS

(@ V+ = +5.0 V, V– = V

= 0 V, TA = +25ⴗC unless otherwise noted)

GND

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS

Offset Voltage V

OS

–40°C ≤ T

Offset Voltage Drift ∆V

Input Bias Current I

Input Offset Current I
Input Common-Mode Voltage Range V

/∆T4µV/°C

OS

B

I

B

OS

CM

V

= 0 V –6 –3 µA

CM

–40°C ≤ TA ≤ +85°C –7 –3.5 µA

V

= 0 V ±4 µA

CM

Common-Mode Rejection Ratio CMRR 0 V ≤ V

R

Large Signal Voltage Gain A
Input Capacitance C

VO

IN

= 10 kΩ 3000 V/V

L

≤ +85°C8mV

A

0.0 +3.0 V

≤ +3.0 V 65 85 dB

CM

2.3 7 mV

3.0 pF

LATCH ENABLE INPUT

Logic “1” Voltage Threshold V
Logic “0” Voltage Threshold V
Logic “1” Current I
Logic “0” Current I

IH

IL

IH

IL

V

= 3.0 V –1.0 –0.3 µA

LH

V

= 0.3 V –4 –2 µA

LL

2.0 1.65 V

1.60 0.8 V

Latch Enable

Pulsewidth t
Setup Time t
Hold Time t

PW(E)

S

H

6ns
1ns

1.2 ns

DIGITAL OUTPUTS

Logic “1” Voltage V
Logic “1” Voltage V
Logic “0” Voltage V

OH

OH

OL

I

= –50 µA, ∆V

OH

I

= –3.2 mA, ∆V

OH

I

= 3.2 mA, ∆V

OL

> 250 mV 3.5 V

IN

> 250 mV 2.4 3.5 V

IN

> 250 mV 0.25 0.4 V

IN

DYNAMIC PERFORMANCE␣

Propagation Delay t

Propagation Delay t

P

P

200 mV Step with 100 mV Overdrive 6.75 9.8 ns

–40°C ≤ T

≤ +85°C813ns

A

100 mV Step with 5 mV Overdrive 8 ns

Differential Propagation Delay

(Rising Propagation Delay vs.

Falling Propagation Delay) ∆t

P

100 mV Step with 100 mV Overdrive

1

0.5 2.0 ns

Rise Time 20% to 80% 3.8 ns

Fall Time 80% to 20% 1.5 ns

POWER SUPPLY␣

Power Supply Rejection Ratio PSRR +4.5 V ≤ V+ ≤ +5.5 V 50 65 dB

Positive Supply Current I+ 4.5 6.0 mA

Ground Supply Current I

GND

–40°C ≤ T

VO = 0 V, RL =

–40°C ≤ T

≤ +85°C 7.5 mA

A

∞

≤ +85°C 3.8 mA

A

2.2 3.3 mA

Analog Supply Current I– 2.3 4.5 mA

–40°C ≤ TA ≤ +85°C 5.5 mA

NOTES

1

Guaranteed by design.

Specifications subject to change without notice.

–2– REV. 0

AD8561

ELECTRICAL SPECIFICATIONS

(@ V+ = +5.0 V, V– = V

= 0 V, V– = –5 V, TA = +25ⴗC unless otherwise noted)

GND

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS

Offset Voltage V

OS

–40°C ≤ T

Offset Voltage Drift ∆V

Input Bias Current I

Input Offset Current I
Input Common-Mode Voltage Range V

/∆T4µV/°C

OS

B

I

B

OS

CM

V

= 0 V –6 –3 µA

CM

–40°C ≤ TA ≤ +85°C –7 –2.5 µA

V

= 0 V ±4 µA

CM

Common-Mode Rejection Ratio CMRR –5.0 V ≤ V

R

Large Signal Voltage Gain A
Input Capacitance C

VO

IN

= 10 kΩ 3000 V/V

L

≤ +85°C8mV

A

–5.0 +3.0 V

≤ +3.0 V 65 85 dB

CM

17 mV

3.0 pF

LATCH ENABLE INPUT

Logic “1” Voltage Threshold V
Logic “0” Voltage Threshold V
Logic “1” Current I
Logic “0” Current I

IH

IL

IH

IL

V

= 3.0 V –1 –0.5 20 µA

LH

V

= 0.3 V –4 –2 20 µA

LL

2.0 1.65 V

1.60 0.8 V

Latch Enable

Pulsewidth t
Setup Time t
Hold Time t

PW(E)

S

H

6ns

1.0 ns

1.2 ns

DIGITAL OUTPUTS

Logic “1” Voltage V
Logic “0” Voltage V

OH

OL

IOH = –3.2 mA 2.6 3.5 V
IOL = 3.2 mA 0.2 0.3 V

DYNAMIC PERFORMANCE␣

Propagation Delay t

Propagation Delay t

P

P

200 mV Step with 100 mV Overdrive 6.5 9.8 ns

–40°C ≤ T

≤ +85°C813ns

A

100 mV Step with 5 mV Overdrive 7 ns

Differential Propagation Delay

(Rising Propagation Delay vs.

Falling Propagation Delay) ∆t

P

100 mV Step with 100 mV Overdrive

1

0.5 2 ns

Rise Time 20% to 80% 3.8 ns

Fall Time 80% to 20% 1.5 ns

Dispersion 1ns

POWER SUPPLY

Power Supply Rejection Ratio PSRR ±4.5 V ≤ V

Supply Current V

= 0 V, RL =

O

and V

CC

≤ ±5.5 V 55 70 dB

EE

∞

Positive Supply Current I+ 4.7 6.5 mA

≤ +85°C 7.5 mA

A

∞

≤ +85°C 3.8 mA

A

2.2 3.3 mA

Ground Supply Current I

GND

–40°C ≤ T

VO = 0 V, RL =

–40°C ≤ T

Negative Supply Current I– 2.4 4.5 mA

–40°C ≤ TA ≤ +85°C 5.5 mA

NOTES

1

Guaranteed by design.

Specifications subject to change without notice.

–3–REV. 0

AD8561–SPECIFICATIONS

WARNING!

ESD SENSITIVE DEVICE

ELECTRICAL SPECIFICATIONS

(@ V+ = +3.0 V, V– = V

= 0 V, TA = +25ⴗC unless otherwise noted)

GND

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS␣

Offset Voltage V
Input Bias Current I

Input Common-Mode Voltage Range V

OS

B

I

B

CM

V

= 0 V –6 –3.0 µA

CM

–40°C ≤ TA ≤ +85°C–7–4µA

0 +1.5 V

7mV

Common-Mode Rejection Ratio CMRR 0.1 V ≤ VCM ≤ 1.5 V 60 dB

OUTPUT CHARACTERISTICS␣

Output High Voltage V
Output Low Voltage V

OH

OL

IOH = –3.2 mA, VIN > 250 mV 1.2
IOL = +3.2 mA, VIN > 250 mV 0.3 V

1

V

POWER SUPPLY␣

Power Supply Rejection Ratio PSRR +2.7 V ≤ V

Supply Currents V

= 0 V, RL =

O

, V

≤ +6 V 40 dB

CC

EE

∞

V+ Supply Current I+ 4.0 4.5 mA

≤ +85°C 5.5 mA

A

1.6 2.5 mA

≤ +85°C 3.0 mA

A

Ground Supply Current I

–40°C ≤ T

GND

–40°C ≤ T

V– Supply Current I– 2.4 3.3 mA

–40°C ≤ TA ≤ +85°C 3.8 mA

DYNAMIC PERFORMANCE␣

Propagation Delay t

NOTES

1

Output high voltage without pull-up resistor. It may be useful to have a pull-up resistor to V+ for 3 V operation.

2

Guaranteed by design.

Specifications subject to change without notice.

P

100 mV Step with 20 mV Overdrive

2

8.5 9.8 ns

ABSOLUTE MAXIMUM RATINGS

Total Analog Supply Voltage . . . . . . . . . . . . . . . . . . . . . +14 V

Digital Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . +14 V

Analog Positive Supply–Digital Positive Supply . . . . . –600 mV

Input Voltage

1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±7 V

Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . ±8 V

Output Short-Circuit Duration to GND . . . . . . . . . Indefinite

Storage Temperature Range

N, R, RU Package . . . . . . . . . . . . . . . . . . –65°C to +150°C

Operating Temperature Range . . . . . . . . . . . –40°C to +85°C

Package Type ␪

8-Lead Plastic DIP (N) 103 43 °C/W
8-Lead SO (R) 158 43 °C/W
8-Lead TSSOP 240 43 °C/W

NOTES

1

The analog input voltage is equal to ±7 V or the analog supply voltage, whichever

is less.

2

θJA is specified for the worst case conditions, i.e., θ

for P-DIP and θ

TSSOP packages.

is specified for device soldered in circuit board for SOIC and

JA

Junction Temperature Range

N, R, RU Package . . . . . . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature Range (Soldering, 10 sec) . . . . . . . +300°C

ORDERING GUIDE

Temperature Package Package

Model Range Description Options

AD8561AN –40°C to +85°C 8-Lead Plastic DIP N-8
AD8561ARU –40°C to +85°C 8-Lead Thin Shrink Small Outline RU-8
AD8561AR –40°C to +85°C 8-Lead Small Outline IC SO-8

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 AD8561 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.

–4– REV. 0

2

JA

␪

JC

is specified for device in socket

JA

Units

AD8561

OVERDRIVE – mV

PROPAGATION DELAY – ns

20

15

0

0

10 50

20 30 40

10

5

VS = 5V, SINGLE SUPPLY
STEP SIZE = 100mV

CAPACITANCE LOAD = 10pF

TA = +258C

SUPPLY VOLTAGE – Volts

PROPAGATION DELAY – ns

20

15

0

4.5 4.75 5.5

5 5.25

10

5

SINGLE SUPPLY,
STEP SIZE = 100mV
OVERDRIVE = 5mV
CAPACITANCE LOAD = 10pF

TA = +258C

TEMPERATURE – 8C

TIME – ns

4

3

0

–50 –25 125

0 255075100

2

1

HOLD TIME

SET-UP TIME

Typical Performance Characteristics

5

+1258C

4

3

2

OUTPUT VOLTAGE – Volts

1

0

–2.5 –2.0 1.5

DIFFERENTIAL INPUT VOLTAGE – mV

VS = 5V, SINGLE SUPPLY

–408C

+258C

–1.5 –1.0 –0.5 0 0.5 1.0

Figure 1. Output Voltage vs. Differen­tial Input Voltage

20

VS = 5V, SINGLE SUPPLY
STEP SIZE = 100mV

OVERDRIVE LOAD = 5mV

15

tPD –

10

5

PROPAGATION DELAY – ns

FALLING EDGE

tPD +

FALLING EDGE

500

400

300

200

100

NUMBER OF COMPARATORS

0

–5 5–4 –3 –2 –1 0 1 2 3 4

Figure 2. Typical Distribution of Input
Offset Voltage

40

VS = 5V, SINGLE SUPPLY
OVERDRIVE = 10mV

CAPACITANCE LOAD = 10pF

30

20

10

PROPAGATION DELAY – ns

(V+ = +5 V, V– = 0 V, TA = +25ⴗC unless otherwise noted)

INPUT VOLTAGE – mV

Figure 3. Propagation Delay vs.
Overdrive

TA = +258C

STEP SIZE = 800mV

400mV

200mV

100mV

0

0

20 30 40

10 50

LOAD CAPACITANCE – pF

Figure 4. Propagation Delay vs. Load
Capacitance

20

VS = +5V, SINGLE SUPPLY
STEP SIZE = 100mV

OVERDRIVE = 5mV,

15

LOAD CAPACITANCE = 10pF

10

5

PROPAGATION DELAY – ns

0

–50

–25

025

Figure 7. Propagation Delay vs.
Temperature

TEMPERATURE – 8C

50

75 100 125

0

0.5 2

0

SOURCE RESISTANCE – kV

1 1.5

Figure 5. Propagation Delay vs.
Source Resistance

20

+258C

15

–408C

10

5

VS = 5V

PROPAGATION DELAY – ns

STEP SIZE = 100mV
OVERDRIVE = 5mV
LOAD CAPACITANCE = 10pF

0

0

COMMON-MODE VOLTAGE – Volts

23 4

15

+1258C

Figure 8. Propagation Delay vs. V

–5–REV. 0

CM

Figure 6. Propagation Delay vs. Posi­tive Supply Voltage

Figure 9. Latch Setup-and-Hold Time
vs. Temperature

AD8561

TEMPERATURE – 8C

I–, ANALOG SUPPLY CURRENT – mA

0

–1.0

–5.0

–75 –50 150–25 0 25 75 100 12550

–2.0

–3.0

–4.0

V+ = 5V, V– = 0V

V+ = 5V, V– = –5V

INPUT COMMON-MODE VOLTAGE – Volts

INPUT BIAS CURRENT – mA

0

–1

–5

–7.5 5

–5 –2.5 0 2.5

–2

–3

–4

0.5

0.4

0.3
TA = –408C

0.2

0.1

OUTPUT LOW VOLTAGE – Volts

TA = +1258C

0

36912

015

SINK CURRENT – mA

Figure 10. Output Low Voltage, V

TA = +258C

OL

vs. Sink Current

0

–1.0

TA = –408C

–2.0

TA = +258C

–3.0

–4.0

I–, ANALOG SUPPLY CURRENT – mA

–5.0

46810

212

TA = +1258C

SUPPLY VOLTAGE –Volts

Figure 13. Analog Supply Current vs.
Supply Voltage for +5 V, –5 V Supplies

5.0

4.4
TA = +1258C

3.8

3.2

2.6

OUTPUT HIGH VOLTAGE – Volts

2.0

015

Figure 11. Output High Voltage, V
vs. Source Current

40

35

30

25

20

15

10

5

POSITIVE SUPPLY CURRENT – mA

0

1 10 100

Figure 14. Positive Supply Current
vs. Frequency

TA = +258C

TA = –408C

36912

SOURCE CURRENT – mA

+1258C

+258C

–408C

FREQUENCY – MHz

OH

Figure 12. Analog Supply Current vs.
Temperature for +5 V, –5 V Supplies

Figure 15. Input Bias Current vs. Input
Common-Mode Voltage for +5 V, –5 V
Supplies

0

–1.0

–2.0

–3.0

–4.0

INPUT BIAS CURRENT – mA

–5.0

–75 –50 150

–25 0 25 75 100 12550

TEMPERATURE – 8C

Figure 16. Input Bias Current vs.
Temperature

–6– REV. 0

AD8561

APPLICATIONS

OPTIMIZING HIGH SPEED PERFORMANCE

As with any high speed comparator or amplifier, proper design
and layout techniques should be used to ensure optimal perfor­mance from the AD8561. The performance limits of high speed
circuitry can easily be a result of stray capacitance, improper
ground impedance or other layout issues.

Minimizing resistance from source to the input is an important
consideration in maximizing the high speed operation of the
AD8561. Source resistance in combination with equivalent
input capacitance could cause a lagged response at the input,
thus delaying the output. The input capacitance of the AD8561
in combination with stray capacitance from an input pin to
ground could result in several picofarads of equivalent capaci-

tance. A combination of 3 kΩ source resistance and 5 pF of

input capacitance yields a time constant of 15 ns, which is
slower than the 5 ns capability of the AD8561. Source imped-

ances should be less than 1 kΩ for the best performance.

It is also important to provide bypass capacitors for the power

supply in a high speed application. A 1 µF electrolytic bypass

capacitor should be placed within 0.5 inches of each power
supply pin, Pin 1 and Pin 4, to ground. These capacitors will
reduce any potential voltage ripples from the power supply. In
addition, a 10 nF ceramic capacitor should be placed as close as
possible from the power supply pins to ground. These capacitors
act as a charge reservoir for the device during high frequency
switching.

A ground plane is recommended for proper high speed perfor­mance. This can be created by using a continuous conductive
plane over the surface of the circuit board, only allowing breaks
in the plane for necessary current paths. The ground plane
provides a low inductive ground, eliminating any potential dif­ferences at different ground points throughout the circuit board
caused from “ground bounce.” A proper ground plane also
minimizes the effects of stray capacitance on the circuit board.

REPLACING THE LT1016

The AD8561 is pin compatible with the LT1016 comparator.
While it is easy to replace the LT1016 with the higher perfor­mance AD8561, please note that there are differences, and it is
useful to check these to ensure proper operation.

There are five major differences between the AD8561 and the
LT1016—input voltage range, input bias currents, speed, out­put swing and power consumption.

When operated on a +5 V single supply, the LT1016 has an
input voltage range from +1.25 V to +3.5 V. The AD8561 has a
wider input range from 0 V to 3.0 V. Signals above 3.0 V may
result in slower response times (see Figure 8). If both signals
exceed 3.0 V, the signals may be shifted or attenuated to bring
them into range, keeping in mind the note about source resis­tance in Optimizing High Speed Performance. If only one of the
signals exceeds 3.0 V only slightly, and the other signal is always
well within the 0 V to 3 V range, the comparator may operate
without changes to the circuit.

Example: A comparator compares a fast moving signal to a
fixed 2.5 V reference. Since the comparator only needs to oper­ate when the signal is near 2.5 V, both signals will be within the
input range (near 2.5 V and well under 3.0 V) when the com­parator needs to change output.

Note that signals much greater than 3.0 V will result increased
input currents and may cause the device to operate more slowly.

The input bias current of the AD8561 is lower (–3 µA typical)
than the LT1016 (+5 µA typical), and the current flows out of

the AD8561 and into LT1016. If relatively low value resistors
and/or low impedance sources are used on the inputs, the volt­age shift due to bias current should be small.

The AD8561 (6.75 ns typical) is faster than the LT1016 (10 ns
typical). While this is beneficial to many systems, timing may
need to be adjusted to take advantage of the higher speed.

The AD8561 has slightly more output voltage swing, from 0.2 V
above ground to within 1.1 V of the positive supply voltage.

The AD8561 uses less current (typically 5 mA) than the LT1016
(typically 25 mA).

INCREASING OUTPUT SWING

Although not required for normal operation, the output voltage

swing of the AD8561 can be increased by connecting a 5 kΩ

resistor from the output of the device to the V+ power supply.
This configuration can be useful in low voltage power supply
applications where maximizing output voltage swing is impor-

tant. Adding a 5 kΩ pull-up resistor to the device’s output will

not adversely affect the specifications of the AD8561.

OUTPUT LOADING CONSIDERATIONS

The AD8561 output can deliver up to 40 mA of output current
without any significant increase in propagation delay. The
output of the device should not be connected to more than
twenty (20) TTL input logic gates, or drive a load resistance

less than 100 Ω.

To ensure the best performance from the AD8561 it is impor­tant to minimize capacitive loading of the output of the device.
Capacitive loads greater than 50 pF will cause ringing on the
output waveform and will reduce the operating bandwidth of
the comparator.

SETUP AND HOLD TIMES FOR LATCHING THE
OUTPUT

The latch input, Pin 5, can be used to retain data at the output
of the AD8561. When the voltage at the latch input goes high,
the output of the device will remain constant regardless of the
input voltages. The setup time for the latch is 2 ns–3 ns and the
hold time is 3 ns. This means that to ensure data retention at
the output, the input signal must be valid at least 5 ns before
the latch pin goes high and must remain valid at least 3 ns after
the latch pin goes high. Once the latch input voltage goes low,
new output data will appear in approximately 8 ns.

A logic high for the latch input is a minimum of +2.0 V and a
logic low is a maximum of +0.8 V. This makes the latch input
easily interface with TTL or CMOS logic gates. The latch
circuitry in the AD8561 has no built-in hysteresis.

–7–REV. 0

AD8561

INPUT STAGE AND BIAS CURRENTS

The AD8561 uses a PNP differential input stage that enables
the input common-mode range to extend all the way from the
negative supply rail to within 2.2 V of the positive supply rail.
The input common-mode voltage can be found as the average
of the voltage at the two inputs of the device. To ensure the
fastest response time, care should be taken not to allow the
input common-mode voltage to exceed either of these voltages.

The input bias current for the AD8561 is 3 µA. As with any

PNP differential input stage, this bias current will go to zero on
an input that is high and will double on an input that is low.
Care should be taken in choosing resistor values to be con­nected to the inputs as large resistors could cause significant
voltage drops due to the input bias current.

The input capacitance for the AD8561 is typically 3 pF. This is

measured by inserting a 5 kΩ source resistance to the input and

measuring the change in propagation delay.

USING HYSTERESIS

Hysteresis can easily be added to a comparator through the
addition of positive feedback. Adding hysteresis to a comparator
offers an advantage in noisy environments where it is not desir­able for the output to toggle between states when the input
signal is near the switching threshold. Figure 17 shows a
method for configuring the AD8561 with hysteresis.

The input signal is connected directly to the noninverting input
of the comparator. The output is fed back to the inverting input
through R1 and R2. The ratio of R1 to R1 + R2 establishes the
width of the hysteresis window with V

setting the center of

REF

the window, or the average switching voltage. The Q output will
switch high when the input voltage is greater than V
not switch low again until the input voltage is less than V

and will

HI

LO

as

given in Equation 1:

V

= V

–1–V

()

HI

+

V

LO=VREF

Where V

is the positive supply voltage.

+

The capacitor C

REF



1–



R1+R2



can also be added to introduce a pole into the

F

R1+R2

R1

R1






+V

REF

(1)

feedback network. This has the effect of increasing the amount
of hysteresis at high frequencies. This can be useful when com­paring a relatively slow signal in a high frequency noise environ-

ment. At frequencies greater than f

=

P

2πC

, the hysteresis

R2

F

1

window approaches VHI = V+ – 1 V and VLO = 0 V. At frequen­cies less than f

the threshold voltages remain as in Equation 1.

P

SIGNAL

V

REF

R1

COMPARATOR

R2

C

F

Figure 17. Configuring the AD8561 with Hysteresis

–8– REV. 0

AD8561

SPICE Model

* AD8561 SPICE Macro-Model Typical Values
* 4/98, Ver. 1.0
* TAM / ADSC
*
* Node assignments
* non-inverting input
* | inverting input
* | | positive supply
* | | | negative supply
* ||||Latch
* |||||DGND
* ||||||Q
* |||||||QNOT
* ||||||||
.SUBCKT AD8561 1 2 99 50 80 51 45 65
*
* INPUT STAGE
*
*
Q1 4 3 5 PIX
Q2 6 2 5 PIX
IBIAS 99 5 800E-6
RC1 4 50 1E3
RC2 6 50 1E3
CL1 4 6 1E-12
CIN 1 2 3E-12
VCM1 99 7 1
D1 5 7 DX
EOS 3 1 POLY(1) (31,98) 1E-3 1
*
* Reference Voltage
*
EREF 98 0 POLY(2) (99,0) (50,0) 0 0.5 0.5
RREF 98 0 100E3
*
* CMRR=80dB, ZERO AT 1kHz
*
ECM1 30 98 POLY(2) (1,98) (2,98) 0 0.5 0.5
RCM1 30 31 10E3
RCM2 31 98 1
CCM1 30 31 15.9E-9
*
* Latch Section
*
RX 80 51 100E3
E1 10 98 (4,6) 1
S1 10 11 (80,51) SLATCH1
R2 11 12 1
C3 12 98 10E-12
E2 13 98 (12,98) 1
R3 12 13 500
*
* Power Supply Section

*

–9–REV. 0

AD8561

GSY1 99 52 POLY(1) (99,50) 4E-3 -2.6E-4
GSY2 52 50 POLY(1) (99,50) 3.7E-3 -.6E-3
RSY 52 51 10
*
* Gain Stage Av=250 fp=100MHz
*
G2 98 20 (12,98) 0.25
R1 20 98 1000
C1 20 98 10E-13
D2 20 21 DX
D3 22 20 DX
V1 99 21 DC 0.8
V2 22 50 DC 0.8
*
* Q Output
*
Q3 99 41 46 NOX
Q4 47 42 50 NOX
RB1 43 41 200
RB2 40 42 5E3
CB1 99 41 10E-12
CB2 42 50 5E-12
RO1 46 45 2E3
RO2 47 45 500
EO1 98 43 POLY(1) (20,98) 0 1
EO2 40 98 POLY(1) (20,98) 0 1
*
* Q NOT Output
*
Q5 99 61 66 NOX
Q6 67 62 50 NOX
RB3 63 61 200
RB4 60 62 5E3
CB3 99 61 10E-12
CB4 62 50 5E-12
RO3 66 65 2E3
RO4 67 65 500
EO3 63 98 POLY(1) (20,98) 0 1
EO4 98 60 POLY(1) (20,98) 0 1
*
* MODELS
*
.MODEL PIX PNP(BF=100,IS=1E-16)
.MODEL NOX NPN(BF=100,VAF=130,IS=1E-14)
.MODEL DX D(IS=1E-16)
.MODEL SLATCH1 VSWITCH(ROFF=1E6,RON=500,VOFF=2.1,VON=1.4)
.ENDS AD8561

–10– REV. 0

0.210 (5.33)
MAX

0.160 (4.06)

0.115 (2.93)

0.022 (0.558)

0.014 (0.356)

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

8-Lead Plastic DIP

(N-8)

0.430 (10.92)

0.348 (8.84)

8

14

PIN 1

0.100
(2.54)

BSC

5

0.280 (7.11)

0.240 (6.10)

0.060 (1.52)

0.015 (0.38)

0.070 (1.77)

0.045 (1.15)

0.130
(3.30)
MIN

SEATING
PLANE

0.325 (8.25)

0.300 (7.62)

0.015 (0.381)

0.008 (0.204)

8-Lead Thin Shrink Small Outline

(RU-8)

0.122 (3.10)

0.114 (2.90)

AD8561

C3220–3–6/98

0.195 (4.95)

0.115 (2.93)

0.177 (4.50)

PIN 1

0.006 (0.15)

0.002 (0.05)

SEATING

PLANE

0.1574 (4.00)

0.1497 (3.80)

PIN 1

0.0098 (0.25)

0.0040 (0.10)

SEATING

PLANE

8

5

0.169 (4.30)

1

0.0256 (0.65)
BSC

0.0118 (0.30)

0.0075 (0.19)

4

0.256 (6.50)

0.246 (6.25)

0.0433
(1.10)
MAX

0.0079 (0.20)

0.0035 (0.090)

8-Lead Small Outline IC

(SO-8)

0.1968 (5.00)

0.1890 (4.80)

8

5

0.2440 (6.20)

41

0.2284 (5.80)

0.0688 (1.75)

0.0532 (1.35)

0.0500
(1.27)

BSC

0.0192 (0.49)

0.0138 (0.35)

0.0098 (0.25)

0.0075 (0.19)

8°
0°

8°
0°

0.028 (0.70)

0.020 (0.50)

0.0196 (0.50)

0.0099 (0.25)

0.0500 (1.27)

0.0160 (0.41)

x 45°

PRINTED IN U.S.A.

–11–REV. 0