SY88903 Ver la hoja de datos (PDF) - Micrel

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Fabricante

SY88903

1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER

Micrel 

Micrel, Inc.

1.25Gbps HIGH-SPEED

LIMITING POST AMPLIFIER

Not recommended for new designs

SY88903

SY88903

FEATURES

■ Up to 1.25Gbps operation

■ Low noise

■ Chatter-Free LOS Generation

■ Open Collector TTL LOS Output

■ TTL /EN Input

■ Differential PECL inputs for data

■ Single power supply

■ Designed for use with SY88902 and SY88904

■ Available in a tiny 10-pin (3mm) MSOP

APPLICATIONS

■ 1.25Gbps Gigabit Ethernet

■ 531Mbps and 1062Mbps Fibre Channel

■ 622Mbps SONET

■ Gigabit Interface Converter

DESCRIPTION

The SY88903 limiting post amplifier with its high gain

and wide bandwidth is ideal for use as a post amplifier in

fiber-optic receivers with data rates up to 1.25Gbps.

Signals as small as 5mVp-p can be amplified to drive

devices with PECL inputs. The SY88903 generates a

chatter-free Loss of Signal (LOS) open collector TTL

output.

The SY88903 incorporates a programmble level detect

function to identify when the input signal has been lost.

This information can be fed back to the /EN input of the

device to maintain stability under loss of signal conditions.

Using LOSLVL pin the sensitivity of the level detect can

be adjusted. The LOSLVL voltage can be set by

connecting a resistor divider between VCC and VREF,

Figure 3. Figure 4 shows the relationship between input

level sensitivity and the voltage set on LOSLVL. Figure 5

shows the relationship between input level sensitivity and

resistor divider ratio.

The LOS output is a TTL open collector output that

requires pull-up resistor for proper operation, Figure 1.

+5V

SY88903

LOS

2k

BLOCK DIAGRAM

DIN

DIN

VREF

VCC

GND

LOSLVL

Limiting

Amplifier

M9999-061907

hbwhelp@micrel.com or (408) 955-1690

Figure 1. LOS Output with Desired Rise Time

ECL

Buffer

Level

Detect

Enable

DOUT

DOUT

EN

LOS

Rev.: I

Amendment: /0

1

Issue Date: June 2007

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