General Description
The MAX3272/MAX3272A 2.5Gbps limiting amplifiers
accept a wide range of input voltages and provide a
constant-level output voltage with controlled edge
speeds. Additional features include power detectors
with programmable loss-of-signal (LOS) indication, an
optional squelch function that mutes the data output sig-
nal when the input voltage falls below a programmable
threshold, and an output polarity selector. These parts
exhibit excellent jitter performance and have low power
dissipation.
The MAX3272/MAX3272A feature current-mode logic
(CML) data outputs that are tolerant of inductive con-
nectors, and are available in a 4mm
4mm QFN pack-
age or in die form (MAX3272 only). Along with the
MAX3271, the MAX3272/MAX3272A are ideal for low-
power, compact optical receivers.
Applications
Gigabit Ethernet Optical Receivers
Fibre Channel Optical Receivers
System Interconnects
2.5Gbps Optical Receivers
SONET/SDH Receivers
Features
Single +3.3V Power Supply
33mA Supply Current
5ps Deterministic Jitter
90ps Edge Speed
Output Squelch Function
Programmable Loss-of-Signal Function
CML Output Interface
20-Pin 4mm
4mm QFN or Thin QFN Package
Selectable Output Polarity
MAX3272/MAX3272A
+3.3V, 2.5Gbps Low-Power
Limiting Amplifiers
________________________________________________________________ Maxim Integrated Products
1
Ordering Information
+3.3V
+3.3V
+3.3V
C
AZ
CAZ1
OUTPOL
CAZ2
V
CC
0.1
µF
0.1
µF
TH
SQUELCH
C
CLOS
CLOS
100
IN-
IN+
OUT+
SDI+
SDO+
V
CC
SDO-
SCLKO-
SCLKO+
SDI-
GND
CDR
OUT-
MAX3271
MAX3272/
MAX3272A
MAX3873
LOS
GND
LOSS
OF
SIGNAL
LOS
R
TH
LEVEL
Typical Operating Circuit
19-2269; Rev 3; 11/04
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.
Pin Configuration appears at end of data sheet.
Typical Operating Circuits continue at end of data sheet.
PART
TEMP RANGE
PIN-
PACKAGE
PACKAGE
CODE
MAX3272EGP
-40°C to +85°C
20 QFN
G2044-3
MAX3272E/D
-40°C to +85°C
Dice*
--
MAX3272AETP+ -40°C to +85°C
20 Thin QFN T2044-3
MAX3272AEGP
-40°C to +85°C
20 QFN
G2044-3
+ Denotes Lead-Free Package.
*Dice are designed and guaranteed to operate from -40°C to
+85°C, but are tested only at T
A
= +25°C.
EVALUATION KIT
AVAILABLE
MAX3272/MAX3272A
+3.3V, 2.5Gbps Low-Power
Limiting Amplifiers
2
_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +3.6V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V and T
A
= +25°C, unless otherwise noted.) (Note 1)
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
CC
) .................................-0.5V to +6.0V
Voltage at IN+, IN- ..........................(V
CC
- 2.4V) to (V
CC
+ 0.5V)
Voltage at SQUELCH, CAZ1, CAZ2,
TH, CLOS ...............................................-0.5V to (V
CC
+ 0.5V)
Voltage at LOS, LOS (MAX3272)...........................-0.5V to +6.0V
Voltage at LOS, LOS (MAX3272A) .............-0.5V to (V
CC
+ 0.5V)
Voltage at LEVEL...................................................-0.5V to +2.0V
Voltage at OUTPOL ...............................................-0.5V to +6.0V
Current into LOS, LOS ..........................................-1mA to +9mA
Differential Input Voltage (IN+ - IN-).................................2.5V
P-P
Continuous Current at IN+, IN- ...........................................50mA
Continuous Current at
CML Outputs (OUT+, OUT-) .........................-25mA to +25mA
Continuous Power Dissipation at +85°C
20-Pin Thin QFN (derate 16.9mW/°C above +85°C) ......1.1W
20-Pin QFN (derate 20mW/°C above +85°C) .................1.3W
Storage Ambient Temperature
Range (T
STG
) .................................................-55°C to +150°C
Operating Junction Temperature
Range (T
J
) .....................................................-55°C to +150°C
Die Attach Temperature...................................................+400°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current
I
CC
(Note 2)
33
44
mA
Input Data Rate
2.5
Gbps
Input Voltage Range
V
IN
Differential
15
1200
mV
P-P
Output Deterministic Jitter
(Notes 3, 4, 5)
5
27
ps
P-P
Random Jitter
(Notes 4, 6)
3
ps
RMS
15mV
P-P
< V
IN
30mV
P-P
90
130
Data Output Edge Speed
(20% to 80%)
(Notes 3, 4)
30mV
P-P
V
IN
1200mV
P-P
90
115
ps
Differential Input Resistance
R
IN
IN+ to IN-
95
100
105
Input-Referred Noise
220
µV
RMS
CML Output Voltage
V
OUT
LEVEL open, R
LOAD
= 50
550
750
1200
mV
P-P
Output Signal when Squelched
Outputs AC-coupled
2.2
mV
P-P
Power-Supply Noise Rejection
PSNR
f
2MHz (Note 7)
30
dB
C
AZ
= open
0.9
MHz
Low Frequency Cutoff
f
OC
C
AZ
= 0.1µF
1.5
kHz
Output Resistance
R
OUT
Single ended to V
CC
42.5
50
57.5
2.5GHz
10
Single-Ended Output Return
Loss
2.5GHz to 4.0GHz
9
dB
Differential Input Return Loss
4.0GHz
10
dB
V
IL
0.8
OUTPOL Input Limits
V
IH
2.4
V
LOS Hysteresis
(Notes 3, 4, 8)
2
3.3
dB
C
CLOS
= open (Notes 3, 9, 10)
1
LOS Assert/Deassert Time
C
CLOS
= 0.01µF (Notes 3, 9, 10)
2.3
50
100
µs
Low LOS Assert Level
R
TH
= 20k
(Notes 3, 10)
4.5
6.5
mV
P-P
Low LOS Deassert Level
R
TH
= 20k
(Notes 3, 10)
9.5
12.7
mV
P-P
Medium LOS Assert Level
R
TH
= 1k
(Notes 3, 10)
7.8
12.9
mV
P-P
Medium LOS Deassert Level
R
TH
= 1k
(Notes 3, 10)
17.4
22.4
mV
P-P
High LOS Assert Level
R
TH
= 80
(Notes 3, 10)
24.3
48
mV
P-P
ABSOLUTE MAXIMUM RATINGS
MAX3272/MAX3272A
+3.3V, 2.5Gbps Low-Power
Limiting Amplifiers
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +3.6V, T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V and T
A
= +25°C, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
High LOS Deassert Level
R
TH
= 80
(Notes 3, 10)
73
124.7
mV
P-P
LOS Output High Voltage
Sinking 30µA
2.4
V
LOS Output Low Voltage
Sourcing 1.2mA
0.4
V
Squelch Input Current
400
µA
Note 1:
Dice are designed and guaranteed from -40°C to +85°C but are tested only at T
A
= +25°C.
Note 2:
Supply current measurement excludes the current of the CML output stage (16mA typical). See Figure 1, Power-Supply
Current Measurement.
Note 3:
Guaranteed by design and characterization.
Note 4:
Input edge speed is controlled using 4-pole, lowpass Bessel filters with bandwidth approximately 75% of the maximum
data rate.
Note 5:
Deterministic jitter is measured with a K28.5 pattern (0011 1110 1011 0000 0101). Deterministic jitter is the peak-to-peak
deviation from ideal time crossings, measured at the zero-level crossings of the differential output per ANSI X3.230, Annex A.
Note 6:
Random jitter is measured with the minimum input signal. For Fibre Channel and Gigabit Ethernet applications, the peak-
to-peak random jitter is 14.1 times the RMS random jitter.
Note 7:
Power-supply noise rejection (PSNR) is calculated by the equation PSNR = 20log (
V
CC
/(
V
OUT
)), where
V
OUT
is the
change in differential output voltage due to the power-supply noise,
V
CC
. See Power-Supply Noise Rejection vs.
Frequency in the Typical Operating Characteristics.
Note 8:
Hysteresis is defined as: 20
log(V
LOS-DEASSERT
/V
LOS-ASSERT
).
Note 9:
Response time to a 10dB change in input power. For the specification guaranteed, the power is assumed to switch back
and forth between two levels (separated by 10dB and equidistant from assert and deassert levels) outside of the two
hysteresis thresholds.
Note 10: All power-detect AC parameters are guaranteed with a 2
23
- 1 PRBS, 2.5Gbps input, with the longest possible run of 80CID.
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
600
650
700
750
800
850
900
950
1000
0
10
20
30
40
50
OUTPUT AMPLITUDE
vs. INPUT AMPLITUDE
MAX3272 toc01
V
IN
(mV
P-P
)
V
OUT
(mV
P-P
)
LEVEL = GND
LEVEL = OPEN
20
35
30
25
40
45
50
55
60
65
70
-40
10
-15
35
60
85
SUPPLY CURRENT
vs. AMBIENT TEMPERATURE
MAX3272 toc02
AMBIENT TEMPERATURE (
°C)
SUPPLY CURRENT (mA)
0
6
4
2
8
10
12
14
16
18
20
1
10
100
1000
10,000
DETERMINISTIC JITTER
vs. INPUT AMPLITUDE
MAX3272 toc03
INPUT AMPLITUDE (mV
P-P
)
DETERMINISTIC JITTER (ps
P-P
)
MAX3272/MAX3272A
+3.3V, 2.5Gbps Low-Power
Limiting Amplifiers
4
_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
0
3
2
1
4
5
6
7
8
9
10
1
10
100
1000
10,000
RANDOM JITTER vs. INPUT AMPLITUDE
MAX3272 toc04
INPUT AMPLITUDE (mV
p-p
)
RANDOM JITTER (ps
RMS
)
C
CLOS
= 0.01
µF
V
OUT
V
IN
LOSS-OF-SIGNAL WITH SQUELCH
MAX3272 toc06
20
µs/div
V
LOS
LOSS OF SIGNAL TRESHOLD vs. R
TH
XXXXXXXX
R
TH
(
)
LOS ASSERT (mV)
100k
10k
1k
100
5
10
15
20
25
30
35
40
45
50
0
10
1M
DATA OUTPUT EYE DIAGRAM
(MINIMUM INPUT)
MAX3272 toc08
2.5Gbps
2
23
-1 PRBS
15mV
P-P
INPUT
100ps/div
150mV/
div
DATA OUTPUT EYE DIAGRAM
(MAXIMUM INPUT)
MAX3272 toc09
100ps/div
150mV/
div
2.5Gbps
2
23
-1 PRBS
1200mV
P-P
INPUT
0
20
10
40
30
50
60
1k
100k
10k
1M
10M
POWER-SUPPLY NOISE REJECTION
vs. FREQUENCY
MAX3272 toc10
FREQUENCY (Hz)
POWER-SUPPLY NOISE REJECTION (dB)
0
10
5
25
20
15
40
35
30
45
10M
100M
1G
10G
INPUT RETURN LOSS vs. FREQUENCY
MAX3272 toc11
FREQUENCY (Hz)
INPUT RETURN LOSS (dB)
2.0
3.0
2.5
4.0
3.5
4.5
5.0
-40
85
LOS HYSTERESIS
vs. AMBIENT TEMPERATURE
MAX3272 toc05
AMBIENT TEMPERATURE (
°C)
HYSTERESIS (dB)
10
-15
35
60
R
TH
= 80
R
TH
= 20k
R
TH
= 1k
0
10
5
25
20
15
40
35
30
45
10M
100M
1G
10G
OUTPUT RETURN LOSS vs. FREQUENCY
MAX3272 toc12
FREQUENCY (Hz)
OUTPUT RETURN LOSS (dB)
MAX3272/MAX3272A
+3.3V, 2.5Gbps Low-Power
Limiting Amplifiers
_______________________________________________________________________________________
5
Pin Description
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
15.0
15.5
16.0
16.5
17.0
17.5
18.0
18.5
19.0
100k
1M
10M
100M
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX3272 toc13
FREQUENCY (Hz)
COMMON-MODE REJECTION RATIO (dB)
PIN
NAME
FUNCTION
1, 4, 17
GND
Supply Ground
2
IN+
Noninverted Input Signal
3
IN-
Inverted Input Signal
5
TH
Loss-of-Signal Threshold Pin. Resistor to ground sets the LOS threshold.
6, 12, 15, 20
V
CC
Power Supply
7
CLOS
LO S Ti m e- C onstant C ap aci tor C onnecti on. For S ON E T ap p l i cati ons, C
C L OS
= 0.01µF i s r ecom m end ed .
8
SQUELCH
Squelch Input. The squelch function is disabled when SQUELCH is not connected or set to TTL low
level. When SQUELCH is set to TTL high level and LOS is asserted, the data outputs (OUT+, OUT-)
are forced to static levels.
9
LOS
Noninverted Loss-of-Signal Output. LOS is asserted TTL high when the signal drops below the assert
threshold set by the TH input. The MAX3272 does not have ESD protection on this pin. The
MAX3272A has ESD protection on this pin.
10
LOS
Inverted Loss-of-Signal Output. LOS is asserted TTL low when the signal drops below the assert
threshold set by the TH input. The MAX3272 does not have ESD protection on this pin. The
MAX3272A has ESD protection on this pin.
11
LEVEL
Output Current Level. When this pin is not connected, the CML output current is approximately
16mA. When this pin is connected to ground, the output current increases to about 20mA.
13
OUT-
Inverted Data Output
14
OUT+
Noninverted Data Output
16
OUTPOL
Output Polarity Control Input. Connect to GND for an inversion of polarity through the limiting
amplifier and connect to V
CC
for normal operation.
18
CAZ2
Offset-Correction-Loop Capacitor Connection. A capacitor connected between this pin and CAZ1
extends the time constant of the offset correction loop. Typical value of C
AZ
is 0.1µF.
19
CAZ1
Offset-Correction-Loop Capacitor Connection. A capacitor connected between this pin and CAZ2
extends the time constant of the offset correction loop. Typical value of C
AZ
is 0.1µF.
EP
EXPOSED
PAD
Connect the exposed paddle to board ground for optimal electrical and thermal performance.
0
4
2
8
6
10
12
0
2500
LOS ASSERT AND DEASSERT LEVELS
vs. DATA RATE
MAX3272 toc14
DATA RATE (Mbps)
V
IN
(mV
P-P
)
1000
500
1500
2000
2
23
- 1 PRBS PATTERN
R
TH
= 20k
C
IN
= 0.1
µF
DEASSERT
ASSERT
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