1

SY88923

Micrel, Inc.

M9999-061907

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

DESCRIPTION

■ Up to 2.5Gbps 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 SY88922 and SY88904 or

SY88905

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

The SY88923 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 2.5Gbps. Signals

as small as 5mVp-p can be amplified to drive devices with

PECL inputs. The SY88923 generates a chatter-free Loss

of Signal (LOS) open collector TTL output.

The SY88923 incorporates a programmable 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 condition.

Figure 4 show the relationship between input level sensitivity

relationship between input level sensitivity and resistor

divider ratio.

The LOS output is a TTL open collector output that

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

FEATURES

2.5Gbps HIGH-SPEED

LIMITING POST AMPLIFIER

Not recommended for new designs

SY88923

APPLICATIONS

■ 1.25Gbps Gigabit Ethernet

■ 531Mbps and 1062Mbps Fibre Channel

■ 622Mbps SONET

■ Gigabit interface converter

■ 2.5Gbps SDH/SONET

BLOCK DIAGRAM

Figure 1. LOS Output with Desired Rise Time

SY88923

LOS

+5.0V

2.5k

Limiting

Amplifer

ECL

Buffer

GND

Enable

Level

Detect

EN

LOS

Rev.: F

Amendment: /0

Issue Date:

June 2007