General Description
The MAX3645 limiting amplifier functions as a data
quantizer and is pin compatible with the Mindspeed
MC2045-2 and MC2045-2Y postamplifiers. The amplifi-
er accepts a wide range of input voltages and provides
constant-level positive emitter-coupled logic (PECL)
output voltages with controlled edge speeds.
The MAX3645 features an integrated power detector
with complementary PECL loss-of-signal (LOS) outputs
that indicate when the input power level drops below a
programmable threshold. An optional squelch function
holds the data outputs at static levels during a
LOS condition.
The MAX3645 operates from a single +3.3V or +5.0V
power supply over a -40
°C to +85°C temperature
range. It is available in 16-pin SO and 16-pin QSOP
packages.
Applications
SONET 155Mbps Transceivers
Fast Ethernet Receivers
FDDI 125Mbps Receivers
FTTx Receivers
ESCON Receivers
Features
o Pin Compatible with the Mindspeed
MC2045-2/MC2045-2Y
o 500µV Input Sensitivity (BER = 10
-12
)
o Compatible with 4B/5B Data Coding
o Programmable LOS Threshold
o Stable LOS Threshold Over Supply Range
o Output Disable Function and Automatic Squelch
o Single +3.3V or +5.0V Power Supply
o 18mA Supply Current
MAX3645
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting
Amplifier with Loss-of-Signal Detector
________________________________________________________________ Maxim Integrated Products
1
Ordering Information
19-3026; Rev 0; 10/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
PART
TEMP RANGE
PIN-PACKAGE
MAX3645ESE
-40°C to +85°C
16 SO
MAX3645EEE
-40
°C to +85°C
16 QSOP
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
CAZ2
TH
N.C.
V
CCE
DOUT+
DOUT-
GNDE
LOS
TOP VIEW
MAX3645
SO/QSOP
CAZ1
GNDA
V
CCA
DIN+
DIN-
CSD
DIS
LOS
Pin Configuration
MAX3645
MAX3644*
PIN K
IN
V
CC
V
CC
V
CC
V
CC
OUT-
OUT+
DIN+
DIN-
GNDA
DOUT+
DOUT-
LOS
LOS
DIS
CSD V
CCA
CAZ1
CAZ2
GND
*FUTURE PRODUCT
V
CCE
TH
GNDE
N.C.
0.1
µF
0.1
µF
C
SD
1nF
C
AZ
0.1
µF
R
TH
100
50
50
50
50
V
CC
- 2V
V
CC
- 2V
Typical Application Circuit
MAX3645
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting
Amplifier with Loss-of-Signal Detector
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.97V to +5.5V, PECL outputs are terminated with 50
to V
CC
- 2V, R
TH
= 100
, C
AZ
= 0.1µF, C
SD
= 1nF, T
A
= -40°C to
+85°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Power-Supply Voltage (V
CCA
, V
CCE
) ....................-0.5V to +7.0V
Voltage at CAZ1, CAZ2, DIN+,
DIN-, CSD, DIS, TH ................................-0.5V to (V
CC
+ 0.5V)
PECL Output Current (DOUT+, DOUT-, LOS, LOS) ...........50mA
Differential Voltage between CAZ1 and CAZ2......-1.5V to +1.5V
Differential Voltage between DIN+ and DIN- ........-1.5V to +1.5V
Continuous Power Dissipation (T
A
= +85
°C)
16-Pin SO (derate 8.7mW/
°C above +85°C)................565mW
16-Pin QSOP (derate 8.3mW/
°C above +85°C)...........540mW
Storage Ambient Temperature Range (T
S
).......-65
°C to +160°C
Lead Temperature (soldering, 10s)..............................+300
°C
PARAMETER
SYM B O L CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLY
Supply Current
I
CC
Excludes PECL termination currents
18
27
mA
INPUT SPECIFICATIONS
Input Resistance
R
IN
Single ended; V
IN
= ±200mV
3.3
4.8
6.4
k
Single ended
0.5
Input Sensitivity (Note 1)
V
IN-MIN
Differential
1.0
mV
P-P
Single ended
750
Input Overload (Note 1)
V
IN-MAX
Differential
1500
mV
P-P
Input-Referred Offset Voltage
Unterminated input, output offset divided by
DC gain (Note 2)
2
40
µV
Input Common-Mode Voltage
V
CMM
V
CC
-
0.87
V
Input-Referred RMS Noise
V
IN-NOISE
(Notes 2, 3)
36
50
µV
RMS
DIS Input High
V
IH
PECL or CMOS logic
V
CC
-
1160
V
CC
mV
DIS Input Low
V
IL
PECL or CMOS logic
0
V
CC
-
1480
mV
DIS Input Current
I
IL
, I
IH
0V
V
DIS
V
CC
-10
+10
µA
OUTPUT SPECIFICATIONS
PECL Output-Voltage High
(Notes 1, 2)
V
CC
-
1085
V
CC
-
880
mV
PECL Output-Voltage Low
(Notes 1, 2)
V
CC
-
1830
V
CC
-
1555
mV
Data Output Transition Time
t
R
, t
F
20% to 80% (Notes 1, 2, 4)
0.7
1.4
ns
Pulse-Width Distortion
PWD
(Notes 1, 2, 4, 5)
30
200
ps
MAX3645
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting
Amplifier with Loss-of-Signal Detector
_______________________________________________________________________________________
3
Note 1: Between sensitivity and overload, the output amplitude is >95% of the fully limited amplitude and all AC specifications are met.
Note 2: Guaranteed by design and characterization.
Note 3: Noise is derived from BER measurement.
Note 4: The data input transition time is controlled by a 4th-order Bessel filter with f
-3dB
= 0.75
× data rate.
Note 5: PWD = [(width of wider pulse) - (width of narrower pulse)] / 2, measured with 155Mbps 0011 pattern.
Note 6: All LOS specifications are measured using a 155Mbps 2
23
- 1 PRBS pattern.
Note 7: The signal at the input is switched between two amplitudes, SIGNAL_ON and SIGNAL_OFF, as shown in Figure 1.
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.97V to +5.5V, PECL outputs are terminated with 50
to V
CC
- 2V, R
TH
= 100
, C
AZ
= 0.1µF, C
SD
= 1nF, T
A
= -40°C to
+85°C. Typical values are at V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
PARAMETER
SYM B O L CONDITIONS
MIN
TYP
MAX
UNITS
TRANSFER CHARACTERISTICS
Bandwidth
Gain = 60dB
150
250
MHz
C
AZ
= open
500
Low-Frequency Cutoff
C
AZ
= 0.1µF
0.5
kHz
LOSS-OF-SIGNAL SPECIFICATIONS (Notes 2, 4, 6)
LOS Sensitivity Range
0
R
TH
2k
2
20
mV
P-P
LOS Hysteresis
10log (V
DEASSERT
/V
ASSERT
)
1.4
2
dB
LOS Assert/Deassert Time
(Note 7)
2.3
80.0
µs
R
TH
= 0
, low setting
0.5
0.9
1.3
R
TH
= 1k
, medium setting
4.8
6.6
8.3
LOS Assert Level
R
TH
= 2k
, high setting
12
17
22
mV
P-P
R
TH
= 0
, low setting
1.1
1.5
1.9
R
TH
= 1k
, medium setting
8.0
10.8
13.5
LOS Deassert Level
R
TH
= 2k
, high setting
20
28
36
mV
P-P
Signal-Dectect Filter Resistance
R
SD
Pin 7
14
20
26
k
Figure 1. Signal Levels for LOS Assert/Deassert Time
Measurement
TIME
V
IN
MAXIMUM DEASSERT LEVEL
1dB
6dB
MAXIMUM POWER-DETECT WINDOW
SIGNAL ON
SIGNAL OFF
MINIMUM ASSERT LEVEL
0V
MAX3645
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting
Amplifier with Loss-of-Signal Detector
4
_______________________________________________________________________________________
Typical Operating Characteristics
(V
CC
= 3.3V, PECL outputs terminated with 50
to V
CC
- 2V, R
TH
= 100
, C
AZ
= 0.1µF, C
SD
= 1nF, T
A
= +25
°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
(EXCLUDES PECL OUTPUT CURRENTS)
MAX3645 toc01
TEMPERATURE (
°C)
SUPPLY CURRENT (mA)
60
35
10
-15
10
15
20
25
30
35
40
45
50
5
-40
85
V
CC
= 5.0V
V
CC
= 3.3V
OUTPUT EYE DIAGRAM
(V
IN
= 1mV
P-P
, 155Mbps, 2
23
- 1PRBS)
MAX3654 toc02
1ns/div
200mV/
div
OUTPUT EYE DIAGRAM
(V
IN
= 1500mV
P-P
, 155Mbps, 2
23
- 1PRBS)
MAX3645 toc03
1ns/div
200mV/
div
TRANSFER FUNCTION
MAX3654 toc04
DIFFERENTIAL INPUT VOLTAGE (mV
P-P
)
DIFFERENTIAL OUTPUT VOLTAGE (mV
P-P
)
10
1
0.1
600
800
1000
1200
1400
1600
1800
2000
400
0.01
100
R
TH
= 1k
R
TH
= 2k
R
TH
= 100
R
TH
= 0
BIT-ERROR RATIO vs.
DIFFERENTIAL INPUT VOLTAGE
MAX3645 toc05
DIFFERENTIAL INPUT VOLTAGE (mV
P-P
)
BIT-ERROR RATIO
0.7
0.6
0.4
0.5
0.2
0.3
0.1
10
-3
10
-4
10
-5
10
-6
10
-7
10
-8
10
-9
10
-10
10
-11
10
-12
0
0.8
155Mbps, 2
23
- 1 PRBS
INPUT-REFERRED RMS NOISE
vs. TEMPERATURE
MAX3645 toc06
TEMPERATURE (
°C)
INPUT-REFERRED NOISE (
µ
V
RMS
)
60
35
10
-15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
15
-40
85
V
CC
= +5.0V
V
CC
= +3.3V
SMALL-SIGNAL GAIN vs. R
TH
MAX3645 toc07
R
TH
(k
)
20log (V
OUT
/V
IN
) (dB)
1.7
1.5
1.0
1.2
0.5
0.7
0.2
10
20
30
40
50
60
70
80
90
100
0
0
2.0
V
IN
= 0.1mV
P-P
LOSS-OF-SIGNAL THRESHOLD
vs. R
TH
(V
CC
= +3.3V AND +5.0V)
MAX3645 toc08
R
TH
(k
)
DIFFERENTIAL INPUT VOLTAGE (mV
P-P
)
1.8
1.6
1.2 1.4
0.4 0.6 0.8 1.0
0.2
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
0
0
2.0
LOS DEASSERT
LOS ASSERT
155Mbps, 2
23
- 1 PRBS
LOSS-OF-SIGNAL HYSTERESIS
vs. TEMPERATURE
MAX3645 toc09
TEMPERATURE (
°C)
10log (DEASSERT/ASSERT) (dB)
60
35
10
-15
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
1.2
-40
85
R
TH
= 2k
R
TH
= 100
R
TH
= 1k
155Mbps, 2
23
- 1 PRBS
MAX3645
+2.97V to +5.5V, 125Mbps to 200Mbps Limiting
Amplifier with Loss-of-Signal Detector
_______________________________________________________________________________________
5
Typical Operating Characteristics (continued)
(V
CC
= 3.3V, PECL outputs terminated with 50
to V
CC
- 2V, R
TH
= 100
, C
AZ
= 0.1µF, C
SD
= 1nF, T
A
= +25
°C, unless otherwise noted.)
LOSS-OF-SIGNAL WITH SQUELCH
(155Mbps, 2
23
- 1PRBS)
MAX3654 toc10
10
µs/div
LOS
V
OUT
V
IN
PULSE-WIDTH DISTORTION
vs. DIFFERENTIAL INPUT VOLTAGE
MAX3645 toc11
DIFFERENTIAL INPUT VOLTAGE (mV
P-P
)
PULSE-WIDTH DISTORTION (ps)
1000
100
10
1
10
20
30
40
50
60
70
80
90
100
0
0.1
10,000
155Mbps 0011 PATTERN
DATA OUTPUT TRANSITION TIME
vs. DIFFERENTIAL INPUT VOLTAGE
MAX3645 toc12
DIFFERENTIAL INPUT VOLTAGE (mV
P-P
)
TRANSITION TIME (ns)
1000
100
10
1
0.5
1.0
1.5
2.0
2.5
3.0
0
0.1
10,000
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