Datasheet

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General Description

The MAX4950A dual PCI Express

(PCIe) equalizer/

redriver operates from a single +3.3V supply. This

device improves signal integrity at the receiver through

programmable input equalization and redrive circuitry

with output deemphasis to correct for high-frequency

losses. This device permits optimal placement of key

PCIe components and longer runs of stripline,

microstrip, or cable.

The MAX4950A contains two identical channels capa-

ble of equalizing PCIe Gen I (2.5GT/s) and Gen II

(5.0GT/s) signals. The MAX4950A features electrical

idle and receiver detection on each channel and a

power-saving mode.

The MAX4950A is available in a small 36-pin (6.0mm x

6.0mm) TQFN package with flowthrough traces for opti-

mal layout and minimal space requirements. The

MAX4950A is specified over the 0°C to +70°C commer-

cial operating temperature range.

Applications

Servers

Industrial PCs

Test Equipment

Computers

External Graphics Applications

Communications Switchers

Storage Area Networks

Features

♦ Single +3.3V Supply Operation

♦ PCIe Gen I (2.5GT/s) and Gen II (5.0GT/s) Capable

Excellent Differential Return Loss:

≥

8dB (f = 1.25GHz to 2.5GHz)

♦ Very Low Latency with 280ps (typ) Propagation

Delay

♦ Individual Lane Detection

♦ Three-Level Programmable Input Equalization

♦ Three-Level Programmable Output Deemphasis

♦ Standard, -2.5dB Programmable Output Levels

♦ On-Chip 50Ω Input/Output Terminations

♦ Space-Saving, 6.0mm x 6.0mm TQFN Package

MAX4950A

Dual PCI Express Equalizer/Redriver

________________________________________________________________

Maxim Integrated Products

19-4583; Rev 0; 4/09

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

PCI Express is a registered trademark of PCI-SIG Corp.

MAX4950A

27 26 25 24 23 22 21 20 19

TOP VIEW

2 3 4 5

TQFN

6 7 8 9

N.C.

ODEA0

ODEA1

O_AMPA

INEQA0

INEQA1

N.C.

GND

INAP

INAM

GND

OUTBP

OUTBM

GND

N.C.

INEQB0

INEQB1

O_AMPB

ODEB0

ODEB1

N.C.

*CONNECT EXPOSED PAD (EP) TO GND.

GND

OUTAP

OUTAM

GND

RX_DET

GND

INBP

INBM

GND

*EP

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX4950ACTX+T 0°C to +70°C 36 TQFN-EP*

Denotes a lead(Pb)-free/RoHS-compliant package.

EP = Exposed pad.

T = Tape and reel.

Pin Configuration

Summary of content (10 pages)

PAGE 1
9-4583; Rev 0; 4/09 Dual PCI Express Equalizer/Redriver The MAX4950A dual PCI Express® (PCIe) equalizer/ redriver operates from a single +3.3V supply. This device improves signal integrity at the receiver through programmable input equalization and redrive circuitry with output deemphasis to correct for high-frequency losses. This device permits optimal placement of key PCIe components and longer runs of stripline, microstrip, or cable.
PAGE 2
MAX4950A Dual PCI Express Equalizer/Redriver ABSOLUTE MAXIMUM RATINGS Junction-to-Case Thermal Resistance (θJC) (Note 2) 36-Pin TQFN...................................................................1°C/W Junction-to-Ambient Thermal Resistance (θJA) (Note 2) 36-Pin TQFN.................................................................28°C/W Operating Temperature Range...............................0°C to +70°C Junction Temperature Range ............................-40°C to +150°C Storage Temperature Range .
PAGE 3
Dual PCI Express Equalizer/Redriver (VCC = +3.0V to +3.6V, CCL = 75nF coupling capacitor on each output, RL = 50Ω resistor on each output, TA = 0°C to +70°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 3) PARAMETER SYMBOL Differential Output Return Loss (Note 5) RLTX-DIFF Common-Mode Output Return Loss (Note 5) RLTX-CM CONDITIONS MIN f = 0.05GHz to 1.25GHz 10 f = 1.25GHz to 2.5GHz 8 f = 0.05GHz to 2.
PAGE 4
MAX4950A Dual PCI Express Equalizer/Redriver ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +3.6V, CCL = 75nF coupling capacitor on each output, RL = 50Ω resistor on each output, TA = 0°C to +70°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.
PAGE 5
Dual PCI Express Equalizer/Redriver INEQ_0 = INEQ_1 = 0, O_AMP_ = 0, VIN = 200mVP-P, ODE_0 = 0, ODE_1 = 0 INEQ_0 = INEQ_1 = 0, O_AMP_ = 0, VIN = 200mVP-P, ODE_0 = 1, ODE_1 = 0 MAX4950A toc01 MAX4950A toc02 600 EYE DIAGRAM VOLTAGE (mV) EYE DIAGRAM VOLTAGE (mV) 600 400 200 0 -200 -400 400 200 0 -200 -400 -600 -600 -150ps-100ps -50ps 0ps 50ps 100ps 150ps -150ps-100ps -50ps 0ps INEQ_0 = INEQ_1 = 0, O_AMP_ = 0, VIN = 200mVP-P, ODE_0 = 0, ODE_1 = 1 INEQ_0 = INEQ_1 = 0, O_AMP_ = 1, VIN = 200mVP-P, OD
PAGE 6
Typical Operating Characteristics (continued) (VCC = +3.3V, TA = +25°C, unless otherwise noted.
PAGE 7
Dual PCI Express Equalizer/Redriver PIN NAME FUNCTION 1, 4, 6, 9, 19, 22, 24, 27 GND Ground 2 INAP Noninverting Input A 3 INAM Inverting Input A 5 EN Enable Input. Drive EN low for standby mode. Drive EN high for normal mode. EN is internally pulled down by a 50k (typ) resistor. 7 OUTBP Noninverting Output B 8 OUTBM Inverting Output B 10, 18, 28, 36 N.C. No Connection. Not internally connected. 11, 17, 29, 35 VCC Power-Supply Input. Bypass VCC to GND with 1μF and 0.
PAGE 8
MAX4950A Dual PCI Express Equalizer/Redriver EN MAX4950A GLOBAL POWER SAVE INEQ_0 INEQ_1 RX_DET O_AMP_ RECEIVER DETECT MANAGER IN_P OUT_P EQUALIZER IN_M EQUALIZER RHI ELECTRICAL IDLE DETECTOR ODE_0 ODE_1 Figure 2.
PAGE 9
Dual PCI Express Equalizer/Redriver The MAX4950A dual equalizer/redriver is designed to support both Gen I (2.5GT/s) and Gen II (5.0GT/s) PCIe data rates. The device contains two identical drivers with idle/receive detect on each lane and equalization to compensate for circuit-board loss. Signal integrity at the receiver is improved by the use of programmable input equalization circuitry.
PAGE 10
Table 5. Quiescent Power Dissipation with Equalization and Deemphasis QUIESCENT POWER QUIESCENT POWER QUIESCENT POWER QUIESCENT POWER SUPPLY CURRENT SUPPLY CURRENT DISSIPATION DISSIPATION (typ) (mA) (max) (mA) (3.3V, typ) (mW) (3.