MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
General Description
The MAX14955 dual equalizer/redriver improves PCI
Express® (PCIe) signal integrity by providing programmable input equalization. This feature reduces deterministic jitter and redrives circuitry to reestablish deemphasis, which compensates for circuit-board loss at high
frequencies. The device permits optimal placement of key
PCIe components and allows for longer runs of stripline,
microstrip, or cable.
The device contains two identical channels capable of
equalizing PCIe Gen III (8GT/s), Gen II (5GT/s), and
Gen I (2.5GT/s) signals and features electrical idle and
receiver detection.
The MAX14955 is available in a small, 40-pin, 5.0mm x
5.0mm TQFN package with flow-through traces for optimal layout and minimal space requirements. The device
is specified over the -40°C to +85°C extending operating
temperature range.
Applications
●
●
●
●
●
●
Benefits and Features
● Fully Integrated for Ease of Use and Design Flexibility
• Optimized for PCIe Gen III (8.0GT/s), Gen II
(5.0GT/s), Gen I (2.5 GT/s) Compatible
• Four Levels of Input Equalization up to 16dB
• Eight Levels of Output Deemphasis up to 9dB
● High Level of Performance to Overcome Noise in
Lossy Channels
• Random Jitter: 0.5psRMS (typ)
• Deterministic Jitter: 7psP-P (typ)
• Equalization Permits Placement Up to 30in FR4
● Robust Solution for Harsh Environments
• Industrial Temperature Rated: -40°C to +85°C
• ±4kV Human Body Model (HBM) Protection on All
Pins
• Housed in a Flow-Through (5mm x 5mm) TQFN
Package for Resistance to Vibration/Shocks
Ordering Information appears at end of data sheet.
Industrial/Embedded PCs
Computer on Modules
Carrier Boards
Test Equipment
Rack Server Industrial PCs
Medical Equipment
For related parts and recommended products to use with this part, refer
to www.maximintegrated.com/MAX14955.related.
Typical Operating Circuit
REMOTE BOARD
MAIN BOARD
MIDPLANE
Tx
SINGLE DIFFERENTIAL PAIR
Rx
MAX14955
PCIe
PCIe
Rx
SINGLE DIFFERENTIAL PAIR
CONNECTORS
PCI Express is a registered service mark of PCI-SIG Corporation.
19-6640; Rev 0; 3/13
Tx
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Absolute Maximum Ratings
Continuous Power Dissipation (TA = +70°C)
TQFN (derate 35.7mW/°C above +70°C)..................2857mW
Operating Temperature Range............................ -40°C to +85°C
Junction Temperature Range............................ -40°C to +150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Soldering Temperature (reflow)........................................+260°C
(Voltages referenced to GND.)
VCC........................................................................-0.3V to +4.0V
All Other Pins (Note 1).............................. -0.3V to (VCC + 0.3V)
Continuous Current IN_P, IN_M,
OUT_P, OUT_M............................................................±30mA
Peak Current IN_P, IN_M, OUT_P, OUT_M
(pulsed for 1µs, 1% duty cycle)...................................±100mA
Note 1: All I/O pins are clamped by internal diodes.
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.
Package Thermal Characteristics (Note 2)
TQFN
Junction-to-Ambient Thermal Resistance (BJA).......... 28NC/W
Junction-to-Case Thermal Resistance (BJC)..................2NC/W
Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Electrical Characteristics
(VCC = +3.0V to +3.6V, CCL = 200nF coupling capacitor on each output, RL = 50Ω on each output, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
3.0
V
DC PERFORMANCE
Power-Supply Range
Supply Current
www.maximintegrated.com
VCC
ICC
EN = VCC
3.3
3.6
OEQ_2 = OEQ_1 = OEQ_0
= GND
102
135
OEQ_2 = OEQ_1 = GND,
OEQ_0 = VCC
106
140
OEQ_2 = OEQ_0 = GND,
OEQ_1 = VCC
107
140
OEQ_2 = GND, OEQ_1 =
OEQ_0 = VCC
125
160
OEQ_2 = VCC, OEQ_1 =
OEQ_0 = GND
106
140
OEQ_2 = OEQ_0 = VCC,
OEQ_1 = GND
132
170
OEQ_2 = OEQ_1 = VCC,
OEQ_0 = GND
140
180
OEQ_2 = OEQ_1 = OEQ_0
= VCC
165
210
mA
Maxim Integrated │ 2
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Electrical Characteristics (continued)
(VCC = +3.0V to +3.6V, CCL = 200nF coupling capacitor on each output, RL = 50Ω on each output, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3)
PARAMETER
Standby Current
SYMBOL
ISTBY
Differential Input Impedance
ZRX-DIFF-
Differential Output Impedance
ZTX-DIFF-
Common-Mode Resistance to
GND, Input Termination Not
Powered
Common-Mode Resistance to
GND, Input Termination Powered
Output Short-Circuit Current
Common-Mode Delta, Between
Active and Idle States
DC Output Offset, During Active
State
DC Output Offset, During
Electrical Idle
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DC
DC
ZRX-HIGHIMP-DC
CONDITIONS
EN = GND
TYP
MAX
OEQ_2 = OEQ_1 = OEQ_0
= GND
57
80
OEQ_2 = OEQ_1 = GND,
OEQ_0 = VCC
61
85
OEQ_2 = OEQ_0 = GND,
OEQ_1 = VCC
62
85
OEQ_2 = GND, OEQ_1 =
OEQ_0 = VCC
75
100
OEQ_2 = VCC, OEQ_1 =
OEQ_0 = GND
62
80
OEQ_2 = OEQ_0 = VCC,
OEQ_1 = GND
85
110
OEQ_2 = OEQ_1 = VCC,
OEQ_0 = GND
92
120
OEQ_2 = OEQ_1 = OEQ_0
= VCC
120
150
100
120
Ω
DC
80
100
120
Ω
-150mV ≤ VIN_CM ≤ +200mV
50
20
Single-ended (Note 4)
DIFF-DC
kΩ
25
30
90
Ω
mA
100
mV
|(VOUT_P - VOUT_M)|
65
mV
|(VOUT_P - VOUT_M)|
65
mV
ACTIVE-IDLEDELTA
VTX-IDLE-
mA
80
VTX-CM-DC-
VTXACTIVEDIFF-DC
UNITS
DC
ZRX-DC
ITX-SHORT
MIN
Maxim Integrated │ 3
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Electrical Characteristics (continued)
(VCC = +3.0V to +3.6V, CCL = 200nF coupling capacitor on each output, RL = 50Ω on each output, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AC PERFORMANCE (Note 4)
Input Return Loss, Differential
RLRX-DIFF
Input Return Loss, Common
Mode
RLRX-CM
Output Return Loss, Differential
RLTX-DIFF
Output Return Loss, Common
Mode
RLTX-CM
Redriver-Operation Differential
Input-Signal Range
VRX-DIFF-
Full-Swing Differential Output
Voltage (No Deemphasis)
VTX-DIFF-
Output Deemphasis Ratio, 0dB
Output Deemphasis Ratio, 3.5dB
Output Deemphasis Ratio, 6dB
Output Deemphasis Ratio, 6dB
with Higher Amplitude
f = 0.05GHz to 1.25GHz
9
dB
f = 1.25GHz to 2.5GHz
8
dB
f = 2.5GHz to 4GHz
5
dB
f = 0.05GHz to 2.5GHz
6
dB
f = 2.5GHz to 4GHz
4
dB
f = 0.05GHz to 1.25GHz
10
dB
f = 1.25GHz to 2.5GHz
8
dB
f = 2.5GHz to 4GHz
4
dB
f = 0.05GHz to 2.5GHz
6
dB
f = 2.5GHz to 4GHz
4
dB
100
PP
PP
2 x |(VOUT_P - VOUT_M)|,
OEQ_2 = OEQ_1 = OEQ_0 = GND
VTX-DERATIO-0dB
OEQ_2 = OEQ_1 = OEQ_0 = GND,
Figure 1
800
1000
1200
mVP-P
1400
mVP-P
0
dB
VTX-DERATIO-3.5dB
OEQ_2 = OEQ_1 = GND, OEQ_0 = VCC,
Figure 1
3.5
dB
VTX-DERATIO-6dB
OEQ_2 = OEQ_0 = GND, OEQ_1 = VCC,
Figure 1
6
dB
VTX-DE-HA- OEQ_2 = GND, OEQ_1 = OEQ_0 = VCC,
RATIO-6dB Figure 1
6
dB
3.5
dB
Output Deemphasis Ratio, 3.5dB VTX-DE-PS- OEQ_2 = VCC, OEQ_1 = OEQ_0 = GND,
with Preshoot
RATIO-3.5dB Figure 1
Output Deemphasis Ratio, 6dB
with Preshoot
VTX-DE-PS- OEQ_2 = OEQ_0 = VCC, OEQ_1 = GND,
RATIO-6dB Figure 1
6
dB
Output Deemphasis Ratio, 9dB
with Preshoot
VTX-DE-PS- OEQ_2 = OEQ_1 = VCC, OEQ_0 = GND,
RATIO-9dB Figure 1
9
dB
Output Deemphasis Ratio,
9dB with Preshoot and Higher
Amplitude
VTX-DE-PS-
OEQ_2 = OEQ_1 = OEQ_0 = VCC,
Figure 1
9
dB
Input Equalization, 5dB
VRX-EQ-5dB INEQ_1 = INEQ_0 = GND (Note 5)
5
dB
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HA-RATIO9dB
Maxim Integrated │ 4
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Electrical Characteristics (continued)
(VCC = +3.0V to +3.6V, CCL = 200nF coupling capacitor on each output, RL = 50Ω on each output, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3)
PARAMETER
Input Equalization, 8dB
SYMBOL
VRX-EQ-
Input Equalization, 16dB
VRX-EQ-
Propagation Delay
Rise/Fall Time
Rise/Fall Time Mismatch
MIN
VRX-EQ-8dB INEQ_1 = GND, INEQ_0 = VCC (Note 5)
Input Equalization, 12dB
Output Common-Mode Voltage
CONDITIONS
12dB
16dB
TYP
dB
INEQ_1 = VCC, INEQ_0 = GND (Note 5)
12
dB
INEQ_1 = INEQ_0 = VCC (Note 5)
16
dB
tPD
FALL
tTX-RFMISMATCH
UNITS
8
VTX-CM-AC- MAX(VOUT_P + VOUT_M)/2 - MIN(VOUT_P
+ VOUT_M)/2
PP
tTX-RISE-
MAX
120
(Note 6)
160
100
mVP-P
240
ps
20
ps
(Note 6)
20
ps
Deterministic Jitter
tTX-DJ-DD
K28.5 pattern, AC-coupled, RL = 50I, no
deemphasis, no preshoot, data rate = 8GT/s
7
23.5
psP-P
Random Jitter
tTX-RJ-DD
D10.2 pattern, no deemphasis, no preshoot,
data rate = 8GT/s
0.5
1.5
psRMS
Electrical Idle Entry Delay
Electrical Idle Exit Delay
From input to output, D10.2 pattern, data
SET-TO-IDLE rate = 1GT/s
tTX-IDLE-
tTX-IDLETO-DIFFDATA
Electrical Idle Detect Threshold
VTX-IDLE-
Output Voltage During Electrical
Idle (AC)
VTX-IDLEDIFF-AC-P
Receiver-Detect Pulse Amplitude
VTX-RCV-
THRESH
From input to output, D10.2 pattern, data
rate = 1GT/s
D10.2 pattern, data rate = 1GT/s (Note 3)
50
D10.2 pattern, data rate = 1GT/s to 8GT/s
5
ns
5
ns
112
190
mVP-P
112
|(VOUT_P - VOUT_M)|
20
600
mV
Receiver-Detect Pulse Width
100
ns
Receiver-Detect Retry Period
200
ns
DETECT
Voltage change in positive direction
mVP-P
CONTROL LOGIC
Input-Logic Level Low
VIL
Input-Logic Level High
VIH
Input-Logic Hysteresis
VHYST
Input Pulldown Resistance
0.6
1.4
RPD
200
V
V
0.1
V
375
kΩ
±4
kV
ESD PROTECTION
ESD Voltage
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Human Body Model (HBM)
Maxim Integrated │ 5
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Electrical Characteristics (continued)
(VCC = +3.0V to +3.6V, CCL = 200nF coupling capacitor on each output, RL = 50Ω on each output, TA = -40°C to +85°C, unless otherwise
noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3)
Note 3: All devices are 100% production tested at TA = +85NC. Specifications over operating temperature range are guaranteed by
design.
Note 4: Guaranteed by design, unless otherwise noted.
Note 5: Equivalent to same amount of deemphasis driving the input.
Note 6: Rise and fall times are measured using 20% and 80% levels.
VLOW_P-P VHIGH_P-P
DE(dB) = 20 log
VHIGH_P- P
VLOW_P-P
Figure 1. Illustration of Output Deemphasis
www.maximintegrated.com
Maxim Integrated │ 6
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
400
VOLTAGE (mV)
200
0
-200
-400
200
400
0
-200
-200 -150 -100 -50
0
50
-600
100 150
200
0
-200
-400
-400
-600
-200 -150 -100 -50
0
50
-600
100 150
-200 -150 -100 -50
0
50
100 150
TIME (ps)
TIME (ps)
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 1, OEQ2 = 0,
DATA RATE = 5GT/s
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 0, OEQ2 = 1,
DATA RATE = 5GT/s
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 0, OEQ2 = 1,
DATA RATE = 5GT/s
400
200
0
-200
-400
200
600
400
VOLTAGE (mV)
VOLTAGE (mV)
400
MAX14955 toc05
MAX14955 toc04
600
0
-200
MAX14955 toc06
TIME (ps)
600
VOLTAGE (mV)
600
VOLTAGE (mV)
400
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 1, OEQ2 = 0,
DATA RATE = 5GT/s
MAX14955 toc02
600
MAX14955 toc01
600
VOLTAGE (mV)
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 0, OEQ2 = 0,
DATA RATE = 5GT/s
MAX14955 toc03
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 0, OEQ2 = 0,
DATA RATE = 5GT/s
200
0
-200
-400
-400
-600
-600
-200 -150 -100 -50
0
TIME (ps)
www.maximintegrated.com
50
100 150
-600
-200 -150 -100 -50
0
TIME (ps)
50
100 150
-200 -150 -100 -50
0
50
100 150
TIME (ps)
Maxim Integrated │ 7
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
400
0
-200
400
0
-200
-400
-400
-200 -150 -100 -50
0
50
100 150
200
0
-200
-400
-600
-600
-600
-200 -150 -100 -50
0
50
100 150
-200 -150 -100 -50
0
50
100 150
INEQ0 = 1, INEQ1 = 0, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 12in MICROSTRIP
ON INPUT, DATA RATE = 5GT/s
INEQ0 = 0, INEQ1 = 1, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 18in
MICROSTRIP ON INPUT, DATA RATE = 5GT/s
INEQ0 = 1, INEQ1 = 1, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 24in
MICROSTRIP ON INPUT, DATA RATE = 5GT/s
VOLTAGE (mV)
200
400
0
-200
200
600
400
VOLTAGE (mV)
400
600
0
-200
200
0
-200
-400
-400
-400
-600
-600
-600
-200 -150 -100 -50
0
TIME (ps)
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50
100 150
-200 -150 -100 -50
0
TIME (ps)
50
100 150
MAX14950A toc12
TIME (ps)
MAX14950A toc11
TIME (ps)
MAX14950A toc10
TIME (ps)
600
VOLTAGE (mV)
200
600
VOLTAGE (mV)
200
600
VOLTAGE (mV)
VOLTAGE (mV)
400
INEQ0 = 1, INEQ1 = 0, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 6in MICROSTRIP
ON INPUT, DATA RATE = 5GT/s
MAX14950A toc09
MAX14955 toc07
600
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 1, OEQ2 = 1,
DATA RATE = 5GT/s
MAX14955 toc08
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 1, OEQ2 = 1,
DATA RATE = 5GT/s
-200 -150 -100 -50
0
50
100 150
TIME (ps)
Maxim Integrated │ 8
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
200
0
-100
-200
100
200
150
VOLTAGE (mV)
VOLTAGE (mV)
100
250
MAX14955 toc14
200
0
-100
0
50
100 150
-100
-250
-200 -150 -100 -50
0
50
-200 -150 -100 -50
100 150
0
50
100 150
TIME (ps)
TIME (ps)
TIME (ps)
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
VOLTAGE (mV)
100
200
0
-100
100
0
-100
-200 -150 -100 -50
0
TIME (ps)
www.maximintegrated.com
50
100 150
100
0
-100
-300
-300
-300
200
-200
-200
-200
300
VOLTAGE (mV)
200
MAX14955 toc17
300
MAX14955 toc16
300
VOLTAGE (mV)
0
-50
-200
-300
-200 -150 -100 -50
50
-150
-200
-300
100
MAX14955 toc18
VOLTAGE (mV)
300
MAX14955 toc13
300
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
MAX14955 toc15
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
-200 -150 -100 -50
0
TIME (ps)
50
100 150
-200 -150 -100 -50
0
50
100 150
TIME (ps)
Maxim Integrated │ 9
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
300
50
0
-50
200
600
400
VOLTAGE (mV)
100
400
VOLTAGE (mV)
100
0
-100
200
0
-200
-100
-200
-150
-300
-400
-200
-400
-250
-500
-600
-200 -150 -100 -50
0
50
-200 -150 -100 -50
100 150
0
50
100 150
-100
-50
0
50
100
TIME (ps)
TIME (ps)
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 0, OEQ2 = 0,
DATA RATE = 8GT/s
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 1,
OEQ2 = 0, DATA RATE = 8GT/s
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 1, OEQ2 = 0,
DATA RATE = 8GT/s
600
MAX14955 toc22
400
VOLTAGE (mV)
200
400
0
-200
200
0
-200
-400
-400
-600
-600
-100
-50
0
TIME (ps)
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50
100
600
400
VOLTAGE (mV)
600
MAX14955 toc24
TIME (ps)
MAX14955 toc23
VOLTAGE (mV)
150
MAX14955 toc20
200
VOLTAGE (mV)
500
MAX14955 toc19
250
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 0, OEQ2 = 0,
DATA RATE = 8GT/s
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
MAX14955 toc21
DATA RATE = 5Gbps,
OUTPUT AFTER 19in STRIPLINE,
INEQ_1 = 0, VIN = 200mVP-P
200
0
-200
-400
-600
-100
-50
0
TIME (ps)
50
100
-100
-50
0
50
100
TIME (ps)
Maxim Integrated │ 10
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
400
0
-200
600
400
VOLTAGE (mV)
200
600
VOLTAGE (mV)
200
0
-200
-400
-400
0
50
100
-100
-50
0
50
100
-100
-50
0
50
100
TIME (ps)
TIME (ps)
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 1, OEQ2 = 1,
DATA RATE = 8GT/s
INEQ0 = 0, INEQ1 = 0, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 6in MICROSTRIP
ON INPUT, DATA RATE = 8GT/s
INEQ0 = 1, INEQ1 = 0, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 12in MICROSTRIP
ON INPUT, DATA RATE = 8GT/s
MAX14955 toc28
400
VOLTAGE (mV)
400
600
200
0
-200
-400
-600
-800
-100
-50
0
TIME (ps)
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50
100
200
600
400
VOLTAGE (mV)
600
MAX14950A toc29
TIME (ps)
800
VOLTAGE (mV)
-200
-600
-600
-50
0
-400
-600
-100
200
0
-200
200
0
-200
-400
-400
-600
-600
-100
-50
0
TIME (ps)
50
100
MAX14950A toc30
VOLTAGE (mV)
400
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 1, OEQ2 = 1,
DATA RATE = 8GT/s
MAX14955 toc27
MAX14955 toc25
600
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 1, OEQ1 = 0, OEQ2 = 1,
DATA RATE = 8GT/s
MAX14955 toc26
INEQ0 = INEQ1 = 0, VIN = 200mVP-P,
OEQ0 = 0, OEQ1 = 0, OEQ2 = 1,
DATA RATE = 8GT/s
-100
-50
0
50
100
TIME (ps)
Maxim Integrated │ 11
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
0
-200
200
0
-200
200
100
0
-100
-400
-200
-600
-600
-300
0
50
100
-100
-50
50
250
200
150
0
-100
100
50
0
-100
-150
-100
-200
-250
0
TIME (ps)
www.maximintegrated.com
50
100
50
100
300
200
100
0
-100
-200
-200
-300
0
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
VOLTAGE (mV)
VOLTAGE (mV)
100
-50
-50
TIME (ps)
MAX14955 toc35
200
-100
-100
100
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
MAX14955 toc34
300
0
TIME (ps)
MAX14595 toc36
-50
TIME (ps)
VOLTAGE (mV)
300
-400
-100
MAX14955 toc33
400
VOLTAGE (mV)
200
600
VOLTAGE (mV)
400
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
MAX14950A toc32
600
VOLTAGE (mV)
INEQ0 = 1, INEQ1 = 1, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 24in MICROSTRIP
ON INPUT, DATA RATE = 8GT/s
MAX14950A toc31
INEQ0 = 0, INEQ1 = 1, VIN = 500mVP-P,
OEQ0 = OEQ1 = OEQ2 = 0, 18in MICROSTRIP
ON INPUT, DATA RATE = 8GT/s
-300
-100
-50
0
TIME (ps)
50
100
-100
-50
0
50
100
TIME (ps)
Maxim Integrated │ 12
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Typical Operating Characteristics (continued)
(VCC = +3.3V, TA = +25NC, unless otherwise noted.)
MAX14955 toc37
250
200
100
300
200
VOLTAGE (mV)
50
0
-100
-150
-100
0
-100
-200
-200
-300
-250
-100
-50
0
50
100
-100
-50
0
50
100
TIME (ps)
TIME (ps)
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
500
MAX14955 toc39
250
200
150
100
400
300
VOLTAGE (mV)
VOLTAGE (mV)
100
50
0
-100
-150
-100
MAX14955 toc40
VOLTAGE (mV)
150
MAX14955 toc38
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
DATA RATE = 8Gbps, OUTPUT AFTER
19in STRIPLINE, INEQ_0 = INEQ_1 = 0,
VIN = 200mVP-P
200
100
0
-100
-200
-300
-200
-400
-250
-500
-100
-50
0
TIME (ps)
www.maximintegrated.com
50
100
-100
-50
0
50
100
TIME (ps)
Maxim Integrated │ 13
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
GND
21
INBP
24 23 22
GND
GND
RXDET
28 27 26 25
INBM
30 29
OUTAM
GND
I.C.
TOP VIEW
OUTAP
Pin Configuration
GND 31
20 I.C.
I.C. 32
19 I.C.
VCC 33
18 VCC
I.C. 34
17 I.C.
OEQA0 35
16 INEQB0
MAX14955
OEQA1 36
15 INEQB1
14 OEQB0
OEQA2 37
INEQA0 38
13 OEQB1
EP*
+
INEQA1 39
12 OEQB2
11 VCC
4
5
6
7
GND
INAP
INAM
GND
EN
GND
TQFN
(5mm x 5mm)
8
9
10
GND
3
OUTBM
2
OUTBP
1
GND
VCC 40
*EXPOSED PAD. CONNECT TO GND.
Pin Description
PIN
NAME
1, 2, 5, 7, 10,
21, 24, 26,
29, 31
GND
FUNCTION
Ground
3
INAP
Noninverting Input, Channel A
4
INAM
Inverting Input, Channel A
6
EN
8
OUTBP
Noninverting Output, Channel B
Inverting Output, Channel B
Enable Input. Drive EN low for standby mode. Drive EN high for normal mode. EN has a 375kI (typ)
internal pulldown resistor.
9
OUTBM
11, 18, 33,
40
VCC
Power-Supply Input. Bypass VCC to GND with 0.1FF and 0.01FF capacitors in parallel as close as
possible to the device.
12
OEQB2
Output Deemphasis Control MSB, Channel B. OEQB2 has a 375kI (typ) internal pulldown resistor.
13
OEQB1
Output Deemphasis Bit 1, Channel B. OEQB1 has a 375kI (typ) internal pulldown resistor.
www.maximintegrated.com
Maxim Integrated │ 14
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Pin Description (continued)
PIN
NAME
14
OEQB0
FUNCTION
Output Deemphasis Control LSB, Channel B. OEQB0 has a 375kI (typ) internal pulldown resistor.
15
INEQB1
Input Equalization Control MSB, Channel B. INEQB1 has a 375kI (typ) internal pulldown resistor.
16
INEQB0
Input Equalization Control LSB, Channel B. INEQB0 has a 375kI (typ) internal pulldown resistor.
17, 19, 20,
30, 32, 24
I.C.
Internally Connected. Leave I.C. unconnected.
22
INBM
Inverting Input, Channel B
23
INBP
Noninverting Input, Channel B
25
RXDET
Receiver Detection Control Bit. Toggle RXDET to initiate receiver detection. RXDET has a 375kI (typ)
internal pulldown resistor.
27
OUTAM
Inverting Output, Channel A
28
OUTAP
Noninverting Output, Channel A
35
OEQA0
Output Deemphasis Control LSB, Channel A. OEQA0 has a 375kI (typ) internal pulldown resistor.
36
OEQA1
Output Deemphasis Control Bit 1, Channel A. OEQA1 has a 375kI (typ) internal pulldown resistor.
37
OEQA2
Output Deemphasis Control MSB, Channel A. OEQA2 has a 375kI (typ) internal pulldown resistor.
38
INEQA0
Input Equalization Control LSB, Channel A. INEQA0 has a 375kI (typ) internal pulldown resistor.
39
INEQA1
Input Equalization Control MSB, Channel A. INEQA1 has a 375kI (typ) internal pulldown resistor.
—
EP
www.maximintegrated.com
Exposed Pad. Internally connected to GND. Connect EP to a large ground plane to maximize thermal
performance and ground conductivity to the device. Do not use EP as the only GND connection.
Maxim Integrated │ 15
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Functional Diagram
EN RXDET
OEQ_2
RECEIVER DETECT
MANAGER
EQUALIZER
IN_P
IN_M
OUT_P
EQUALIZER
INEQ_0
INEQ_1
OUT_M
OUTPUT
ENABLE
RHI
MAX14955
ELECTRICAL IDLE
DETECTOR
OEQ_0
OEQ_1
Detailed Description
The MAX14955 dual equalizer/redriver supports Gen
III (8GT/s), Gen II (5GT/s), and Gen I (2.5GT/s) PCIe
data rates. The device contains two identical drivers
with idle/receive detect on each lane and equalization/
deemphasis/preshoot to compensate for circuit board
loss. Programmable input equalization circuitry reduces
deterministic jitter, improving signal integrity. The device
features programmable output deemphasis/preshoot,
permitting optimal placement of key PCIe components
and longer runs of stripline, microstrip, or cable.
Programmable Input Equalization
Programmable input equalization for channel A is controlled by two bits: INEQA1 and INEQA0 and for channel
B is controlled by two bits: INEQB1 and INEQB0 (Table 1.)
Programmable Output Deemphasis
Programmable output deemphasis/preshoot for channel A
is controlled by the three bits: OEQA2, OEQA1, OEQA0
and channel B is controlled by the three bits: OEQB2,
OEQB1, OEQB0 (Table 2.)
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Receiver Detection
The device features receiver detection on each channel.
Upon initial power-up, if EN is high, receiver detection
initializes. Receiver detection can also be initiated on a
rising or falling edge of the RXDET input when EN is high.
During this time, the part remains in low-power standby
mode and the outputs are squelched, despite the logichigh state of EN. Until a channel has detected a receiver,
the receiver detection repeats indefinitely on each channel. If a channel detects a receiver, the other channel is
limited to a few retries. Upon receiver detection, input
common-mode termination and electrical idle detection
are enabled (Table 3.)
Table 1. Input Equalization
INEQ_1
INEQ_0
INPUT EQUALIZATION (dB)
0
0
5
0
1
8
1
0
12
1
1
16
Maxim Integrated │ 16
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Table 2. Output Deemphasis/Preshoot
OEQ_2
OEQ_1
OEQ_0
OUTPUT DEEMPHASIS
RATIO (dB)
PEAK-TO-PEAK
SWING
PRESHOOT
0
0
0
0
1.0V
No
0
0
1
3.5
1.0V
No
0
1
0
6
1.0V
No
0
1
1
6
1.2V
No
1
0
0
3.5
1.0V
Yes
1
0
1
6
1.0V
Yes
1
1
0
9
0.9V
Yes
1
1
1
9
1.0V
Yes
Table 3. Receiver Detection Input Function
RXDET
EN
DESCRIPTION
X
0
Receiver detection is inactive.
X
1
Following a rising edge of EN signal, indefinite retry until a receiver is detected for
at least one channel. Retries stop a few times after any channel is detected.
Rising/falling edge
1
Initiate receiver detection.
X = Don’t care.
Electrical Idle Detection
The device features electrical idle detection to prevent
unwanted noise from being redriven at the output. When
the device detects the differential input has fallen below
the electrical idle low threshold, it squelches the output.
For differential input signals that are above the electrical
idle high threshold, the device turns on the output and
redrives the signal.
Applications Information
Layout
Circuit board layout and design can significantly affect
the performance of the device. Use good high-frequency
design techniques, including minimizing ground inductance and using controlled-impedance transmission lines
on data signals. Power-supply decoupling capacitors must
be placed as close as possible to VCC. Always connect
VCC to a power plane. It is recommended to run receive
and transmit on different layers to minimize crosstalk.
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Exposed-Pad Package
The exposed-pad, 40-pin TQFN package incorporates
features that provide a very low thermal resistance path
for heat removal from the IC. The exposed pad on the
device must be soldered to the circuit board ground plane
for proper thermal performance. For more information on
exposed-pad packages, refer to Maxim Application Note
HFAN-08.1: Thermal Considerations of QFN and Other
Exposed-Paddle Packages.
Power-Supply Sequencing
Caution: Do not exceed the absolute maximum ratings because stresses beyond the listed ratings can
cause permanent damage to the device.
Proper power-supply sequencing is recommended for all
devices. Always apply GND then VCC before applying
signals, especially if the signal is not current limited.
Maxim Integrated │ 17
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Ordering Information
PART
MAX14955ETL+
Package Information
TEMP RANGE
PIN-PACKAGE
-40°C to +85°C
40 TQFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that
a “+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
40 TQFN-EP
T4055+2
21-0140
90-0002
Maxim Integrated │ 18
MAX14955
Single-Lane PCIe Gen III Redriver
with Equalization and Extended
Temperature Operation
Revision History
REVISION
NUMBER
REVISION
DATE
0
3/13
DESCRIPTION
Initial release
PAGES
CHANGED
—
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2013 Maxim Integrated Products, Inc. │ 19
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