SY88923_11 Datasheet, PDF (1/6 Pages) Micrel Semiconductor – 2.5Gbps HIGH-SPEED LIMITING POST AMPLIFIER Not recommended for new designs

Micrel, Inc.
2.5Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
Not recommended for new designs
SY88923
SY88923
FEATURES
■ 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
APPLICATIONS
■ 1.25Gbps Gigabit Ethernet
■ 531Mbps and 1062Mbps Fibre Channel
■ 622Mbps SONET
■ Gigabit interface converter
■ 2.5Gbps SDH/SONET
DESCRIPTION
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.
Using LOSLVL pin, the sensitivity of the level detection can
be adjusted. The LOSLVL voltage can be set by connecting
a resistor divider between VCC and VREF. Figure 3 and
Figure 4 show 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 a pull-up resistor for proper operation, Figure 1.
SY88923
LOS
+5.0V
2.5k
BLOCK DIAGRAM
Figure 1. LOS Output with Desired Rise Time
DIN
DIN
VREF
VCC
GND
Limiting
Amplifer
LOSLVL
ECL
Buffer
Enable
Level
Detect
DOUT
DOUT
EN
LOS
M9999-061907
[e-mail] or [phone]
1
Rev.: F Amendment: /0
Issue Date: June 2007