Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - Custom amplification Limiting amplifier QSOP 20

_______________General Description

The MAX3761/MAX3762 limiting amplifiers, with 4mV

sensitivity and PECL data outputs, are optimized for

operation in low-cost, 622Mbps, LAN/ATM LAN fiber

optics applications.

An integrated power detector senses the input signal’s

amplitude. A received-signal-strength indicator (RSSI)

gives an analog indication of the power level, while the

complementary loss-of-signal (LOS) outputs indicate if

the input power level exceeds the programmed

threshold level. The LOS threshold can be adjusted to

detect signal amplitudes between 3mVp-p and

100mVp-p, providing a 15dB LOS adjustment in fiber

optic receivers. The LOS outputs have 3.5dB of

hysteresis, which prevents chatter when input signal

levels are small. The MAX3761’s LOS outputs are com-

patible with TTL-logic levels. The MAX3762 has PECL

LOS outputs.

DISABLE and LOS can be used to implement a squelch

function, which turns off the data outputs when the

input signal is below the programmed threshold.

________________________Applications

622Mbps LAN/ATM LAN Receivers

155Mbps LAN/ATM LAN Receivers

____________________________Features

♦♦

Chatter-Free Power Detector with Programmable

Loss-of-Signal Outputs

♦♦

4mV Input Sensitivity

♦♦

PECL Data Outputs

♦♦

Single 5V Power Supply

♦♦

250ps Output Edge Speed

♦♦

Low 15ps Pulse-Width Distortion

♦♦

TTL Loss-of-Signal Interface Logic—MAX3761

♦♦

PECL Loss-of-Signal Interface Logic—MAX3762

MAX3761/MAX3762

Low-Power, 622Mbps Limiting Amplifiers

with Chatter-Free Power Detect for LANs

________________________________________________________________

Maxim Integrated Products

CZN

OUT+

OUT-

LOS-

LOS+

DISABLE

SUB

GND

GNDO

100pF

50Ω

CZP

100kΩ

22kΩ

VTH

INV

MAX3761

150pF

50Ω

- 2V

RSSI

VCCO

VIN+

10nF

100pF

BYPASS

SUPPLY

5.6nF

+5V

VIN-

FILTER

_________Typical Operating Circuits

19-1097; Rev 4; 8/08

EVALUATION KIT

AVAILABLE

Ordering Information

Dice are designed to operate from -40°C to +85°C, but are

tested and guaranteed only at T

= +25°C.

Denotes a lead-free/RoHS-compliant package.

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.

__________________Pin Configuration

DISABLE

LOS+

LOS-

RSSI

FILTER

TOP VIEW

VCCO

OUT+

OUT-

GNDO

SUB

GND

VIN-

VIN+

VTH

INV

CZN

CZP

QSOP

MAX3761

MAX3762

MAX3762 at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX3761EEP+ -40°C to +85° C 20 QSOP

MAX3761E/D -40°C to +85°C Dice*

MAX3762EEP+ -40°C to +85° C 20 QSOP

MAX3762E/D -40°C to +85°C Dice*

Summary of content (12 pages)

PAGE 1
9-1097; Rev 4; 8/08 KIT ATION EVALU LE B A IL A AV Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs ____________________________Features The MAX3761/MAX3762 limiting amplifiers, with 4mV sensitivity and PECL data outputs, are optimized for operation in low-cost, 622Mbps, LAN/ATM LAN fiber optics applications. An integrated power detector senses the input signal’s amplitude.
PAGE 2
MAX3761/MAX3762 Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs ABSOLUTE MAXIMUM RATINGS VCC, VCCO............................................................-0.5V to +7.0V FILTER, RSSI, EN, VIN+, VIN-, CZP, CZN, DISABLE, LOS+, LOS-, INV, VTH...............-0.5V to (VCC + 0.5V) PECL Output Current (OUT+, OUT-, LOS+, LOS-) ............50mA Continuous Power Dissipation (TA = +85°C) QSOP (derate 9.1mW/°C above +85°C) .......................
PAGE 3
Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs (VCC = +4.5V to +5.5V, PECL outputs terminated with 50Ω to VCC - 2V, input 4mV to 2Vp-p, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +5.0V, TA = +25°C.) (Note 5) MAX UNITS Minimum LOS Assert Input PARAMETER TA = -40°C, 223 - 1 PRBS CONDITIONS MIN TYP 3.
PAGE 4
____________________________Typical Operating Characteristics (continued) (MAX3761/MAX3762 EV kit, VCC = +5.0V, PECL outputs terminated with 50Ω to VCC - 2V, input is a 1-0 pattern, 622Mbps, TA = +25°C, unless otherwise noted.) 1.68 VIN = 16mVp-p 1.60 1.52 1.44 3.50 3.25 3.00 2.75 5 0 20 40 60 3 -40 80 -20 0 20 40 60 80 0 20 40 60 80 AMBIENT TEMPERATURE (°C) AMBIENT TEMPERATURE (°C) DATA OUTPUT LEVELS (REFERENCE TO VCC) DIFFERENTIAL OUTPUT vs.
PAGE 5
Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs 200mV/ div 50mV/ div 10 RANDOM JITTER (ps rms) DIFFERENTIAL OUTPUT (OUT+ - OUT-) INPUT = 16mVp-p TA = +27°C 1-0 PATTERN 622Mbps MAX3761/62-14 MAX3761/62-13 INPUT = 2Vp-p TA = +85°C RANDOM JITTER vs.
PAGE 6
MAX3761/MAX3762 Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs CAZ VCC GND SUB CZN CZP EN VCCO DISABLE LIMITER LIMITER LIMITER LIMITER VIN+/VIN- OUT+/OUT50Ω CIN FWD FWD FWD VCC - 2V FWD RSSI FILTER LOS+/LOSCFILTER REF VCC MAX3761/MAX3762 INV FWD = FULL-WAVE DETECTOR R1 VTH GNDO R2 Figure 1. Functional Diagram _______________Detailed Description Figure 1 shows the functional diagram for the MAX3761/ MAX3762.
PAGE 7
Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs Output Buffers The DISABLE pin can be used to disable the dataoutput buffer. When DISABLE is high, the differential output signal at OUT+ and OUT- is approximately zero. In the disabled state, the common-mode voltage of each output is approximately VCC - 0.8V. Connecting DISABLE to LOS+ implements a squelch function.
PAGE 8
MAX3761/MAX3762 Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs Capacitor Selection A typical MAX3761/MAX3762 implementation requires four external capacitors. To select the capacitors, first determine the following parameters in the receiver system (see the Applications Information section for recommendations in 622Mbps ATM and Fibre Channel 1063Mbps systems): 1) The duration of the expected longest run of consecutive bits in the data stream.
PAGE 9
Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs Converting Average Optical Power to Signal Amplitude Many of the MAX3761/MAX3762’s specifications relate to input-signal amplitude. When working with fiber optic receivers, the input is usually expressed in terms of average optical power and extinction ratio. The relations given in Table 1 are helpful for converting optical power to input signal when designing with the MAX3761/MAX3762. OPTICAL POWER P1 PAVE P0 Table 1.
PAGE 10
MAX3761/MAX3762 Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs For LOS assert at -35dBm, select R1 = 100kΩ and R2 = 22kΩ, which programs the LOS assert at input ≅ 3mV. With this selection, LOS assert time will typically be less than 85μs. OUT+ Fibre Channel Component Selection In Fibre Channel applications, the desired LOS assert time is typically 25μs maximum, and data-dependent jitter is reduced by 8B10B coding techniques.
PAGE 11
Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs +5V CZN DISABLE LOS+ EN 10nF CAZ 150pF CZP VCC RSSI VCCO CIN 5.6nF OUT+ GNDO VCC - 2V GND FILTER CFILTER INV VCC - 2V 50Ω 50Ω MAX3762 VIN- VCC - 2V 500Ω OUTVIN+ 100pF 500Ω LOS- CIN 5.6nF 100pF VTH SUB +VCC R1 R2 Package Information Chip Topography For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
PAGE 12
MAX3761/MAX3762 Low-Power, 622Mbps Limiting Amplifiers with Chatter-Free Power Detect for LANs Revision History REVISION NUMBER REVISION DATE 0 6/96 1 10/96 2 DESCRIPTION PAGES CHANGED Initial release. — Changed the TTL output voltage to improve yield at cold test. 2 8/01 In the Absolute Maximum Ratings section, corrected a continuous power dissipation error. 2 3 7/04 Added the lead-free package information to the Ordering Information table.