6.25Gbps, 1.8V PC Board Equalizer

________________________________________________________________

Maxim Integrated Products

1

19-2630; Rev 4; 10/08

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.

General Description

The MAX3785 6.25Gbps equalizer operates from a sin-

gle 1.8V supply and compensates for transmission-

medium losses encountered with FR-4 transmission

lines. Optimized for low-voltage, high-density, DC-cou-

pled interconnections between the line card and switch

card, the MAX3785 enables a system upgrade path

while maintaining a legacy rate of 2.5Gbps to

3.125Gbps. Roughly the size of two 0603 passive com-

ponents, the MAX3785 easily provides placement and

routing flexibility.

The MAX3785 is composed of an equalizer, limiting

amplifier, and output driver. For data rates of 3.2Gbps

and lower, the MAX3785 equalizes signals for spans up

to 40in of FR-4 board material. For data rates up to

6.25Gbps, the MAX3785 compensates for 30in of FR-4

board material. The MAX3785 is coding independent,

functioning equally well for 8b/10b or scrambled signals.

The MAX3785 features DC-coupled current-mode logic

(CML) data inputs and outputs. It is packaged in a tiny

1.5mm

× 1.5mm chip-scale package (USCP™) and a

6-pin TDFN package.

Applications

HSBI for

≤ 6.4Gbps

Double IEEE 802.3ae XAUI

Double STM-16/OC-48

Features

♦ Single 1.8V Supply

♦ Very Low Power, 60mW

♦ Spans 30in with FR-4 at 6.25Gbps

♦ Operates from 1.0Gbps to 6.4Gbps

♦ Coding Independent, 8b/10b or Scrambled

♦ DC-Coupled CML Inputs and Outputs

♦ Small 1.5mm × 1.5mm Footprint

Ordering Information

PART

TEMP RANGE

PIN-PACKAGE

MAX3785UBL

0°C to +85°C

6 UCSP (3

3)

MAX3785UWL+

0°C to +85°C

6 WLP

MAX3785UTT

0°C to +85°C

6 TDFN-EP*

MAX3785UTT+

0°C to +85°C

6 TDFN-EP*

MAX3785ITT

-20°C to +85°C

6 TDFN-EP*

MAX3785ITT+

-20°C to +85°C

6 TDFN-EP*

LINE CARD

MAC

Rx

Rx

Tx

Tx

SWITCH CARD

MAX3785

OUT

IN

1.8V

MAX3785

IN

OUT

SWITCH

ASIC WITH

SERDES

Rx

Tx

1.8V

BACKPLANE

6.25Gbps

30in (0.75m)

Typical Application Circuit

UCSP is a trademark of Maxim Integrated Products, Inc.

+

Denotes a lead-free/RoHS-compliant package.

*

EP = Exposed pad.

A1

A2

A3

C1

C2

C3

IN-

GND

OUT-

IN+

OUT+

MAX3785UBL

MAX3785UTT

Δ

3 x 3 UCSP

TDFN

TOP VIEW (BUMPS ON BOTTOM OF DIE)

GND

OUT+

OUT-

1

6

IN+

IN-

2

34

Pin Configurations