1
SY88923AV
Micrel
DESCRIPTION
s
Single 3.3V or 5V power supply
s
Up to 3.2Gbps operation
s
Low noise PECL data outputs
s
Chatter-free open collector TTL LOS output
s
TTL /EN Input
s
Differential PECL inputs for data
s
Available in a tiny 10-pin (3mm) MSOP and 10-pin
(3mm) EPAD-MSOP
The SY88923AV 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
3.2Gbps. Signals as small as 5mVp-p can be amplified
to drive devices with PECL inputs. The SY88923AV
generates a chatter-free Loss-of-Signal (LOS) open
collector TTL output.
The SY88923AV incorporates a programmable level
detect function to identify when the input signal has been
lost. The LOS output will change from logic "LOW" to logic
"HIGH" when input signal is smaller than the swing set by
LOS
LVL
. This information can be fed back to the EN input
of the device to maintain stability under loss-of-signal
condition. Using LOS
LVL
pin, the sensitivity of the level
detection can be adjusted. The LOS
LVL
voltage can be set
by connecting a resistor divider between V
CC
and V
REF
shown in Figure 3.
"Typical Operating Characteristics"
on
page 6 show the relationship between input level sensitivity
and the voltage set on LOS
LVL.
The LOS output is a TTL open collector output that
requires a pull-up resistor for proper operation, Figure 1.
SY88923AV
LOS
4.7k
to 10k
V
CC
Figure 1. LOS Output with Desired Rise Time
FEATURES
5V/3.3V 3.2Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
SY88923AV
Final
APPLICATIONS
s
1.25Gbps and 2.5Gbps Gigabit Ethernet
s
531Mbps, 1062Mbps and 2.12Gbps Fibre Channel
s
622Mbps SONET
s
Gigabit interface converter
s
2.5Gbps SDH/SONET
s
2.5Gbps proprietary links
s
Parallel 10G Ethernet
BLOCK DIAGRAM
Limiting
Amplifer
ECL
Buffer
GND
Enable
Level
Detect
/EN
LOS
D
IN
/D
IN
V
REF
V
CC
LOS
LVL
D
OUT
/D
OUT
Rev.: C
Amendment: /0
Issue Date:
May 22, 2003
2
SY88923AV
Micrel
PACKAGE/ORDERING INFORMATION
Ordering Information
Package
Operating
Package
Part Number
Type
Range
Marking
SY88923AVKC
K10-1
Commercial
923A
SY88923AVKCTR
(Note 1)
K10-1
Commercial
923A
SY88923AVKEC
K10-2
Commercial
923A
SY88923AVKECTR
(Note 1)
K10-2
Commercial
923A
Note 1.
Tape and Reel.
LOSLVL
GND
6
5
1
/EN
DIN
/DIN
VREF
10 VCC
DOUT
/DOUT
LOST
9
8
7
2
3
4
10-Pin MSOP (K10-1)
10-Pin EPAD-MSOP (K10-2)
PIN DESCRIPTION
Pin Number
Pin Number
MSOP
EPAD-MSOP
Pin Name
Type
Pin Function
1
1
/EN
TTL Input
Output Enable (Active Low).
2
2
DIN
Data Input
Data Input.
3
3
/DIN
Data Input
Inverting Data Input.
4
4
VREF
Output
Reference Voltage Output for LOS Level Set (see Figure 3).
5
5
LOSLVL
Input
LOS Limit Set.
6
6,
GND
Ground
Ground. Exposed pad must be connected to PCB ground
(Exposed Pad)
plane.
7
7
LOS
TTL Output
Loss of Signal Indicator (Active High).
(Open Collector)
8
8
/DOUT
PECL Output
Inverting Data Output.
9
9
DOUT
PECL Output
Data Output.
10
10
VCC
Power Supply
Positive Power Supply.
3
SY88923AV
Micrel
Absolute Maximum Ratings
(Note 1)
Power Supply Voltage (V
CC
) ............................ 0V to +7.0V
Input Voltage
(D
IN
, /D
IN
) ........................................................ 0V to V
CC
(/EN) ................................................................ 0V to V
CC
(LOS
LVL
) .......................................................... 0V to V
CC
Output Voltage (with 50
load)
(D
OUT
, /D
OUT
) .......................... V
CC
2.5V to V
CC
+0.3V
(V
REF
) .................................................. V
CC
2.0V to V
CC
Lead Temperature (soldering, 10 sec.) ..................... 270
C
Storage Temperature (T
S
) ....................... 55
C to +125
C
Operating Ratings
(Note 2)
Supply Voltage (V
CC
) .................................. +3.0V to +5.5V
Ambient Temperature (T
A
) ......................... 40
C to +85
C
Package Thermal Resistance
MSOP
(
JA
)
Still-Air ........................................................... 113
C/W
EPAD-MSOP
(
JA
)
Still-Air ............................................................. 38
C/W
V
CC
=+5V
10% or +3.3V
10%; R
L
= 50
to V
CC
2V; T
A
= 40
C to +85
C; unless otherwise noted.
Symbol
Parameter
Condition
Min
Typ
Max
Units
I
CC
Power Supply Current
No output load
V
CC
= 5V
10%,
38
60
mA
V
CC
= 3.3V
10%
35
53
mA
I
IL
/EN Input LOW Current
V
IN
= 0.5V
0.3
mA
I
IH
/EN Input HIGH Current
V
IN
= 2.7V
20
A
V
IN
= V
CC
100
A
V
CMR
Common Mode Range
GND +2.0
V
CC
V
V
offset
Differential Output Offset
80
mV
LOS
LVL
LOS
LVL
Level
V
REF
V
CC
V
V
OL
LOS Output LOW Level
I
OL
= +2mA
0.5
V
I
OH
LOS Output Leakage
V
OH
= 5.5V
100
A
V
OH
D
OUT
and /D
OUT
Output HIGH Voltage
V
CC
1085 V
CC
955
V
CC
880
mV
V
OL
D
OUT
and /D
OUT
Output LOW Voltage
V
CC
1830 V
CC
1705 V
CC
1555
mV
V
REF
Reference Supply
V
CC
1.38 V
CC
1.32 V
CC
1.26
V
I
REF
V
REF
Output Current
0.8
0.5
mA
V
IH
/EN Input HIGH Voltage
2.0
V
V
IL
/EN Input LOW Voltage
0.8
V
Note 1.
The device is guaranteed to meet the DC specifications, shown in the table above, after thermal equilibrium has been established. The device
is tested in a socket such that transverse airflow of
500lfpm is maintained.
DC ELECTRICAL CHARACTERISTICS
(Note 1)
Note 1.
Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation
is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM
RATlNG conditions for extended periods may affect device reliability.
Note 2.
The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
4
SY88923AV
Micrel
V
CC
=+5V
10% or +3.3V
10%; R
L
= 50
to V
CC
2V; T
A
= 40
C to +85
C; unless otherwise noted.
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
ID
Input Voltage Range
5
1800
mVp-p
V
OD
Differential Output Voltage Swing
Note 1
V
ID
= 15mVp-p
1400
mVp-p
V
ID
= 5mVp-p
600
mVp-p
t
ON
LOS Assert Time
Note 2
0.2
0.5
s
t
OFF
LOS Release Time
Note 2
0.1
0.5
s
V
SR
LOS Sensitivity Range
2
23
1 pattern
5
50
mVp-p
HYS
LOS Hysteresis
2
23
1 pattern
2
4.6
8
dB
t
r
, t
f
Output Rise/Fall Time
V
ID
> 100mVp-p
115
150
ps
V
ID
< 100mVp-p
t
rin
,t
fin
Note 1.
Input is a 200MHz square wave, t
r
< 300ps.
Note 2.
Input is a 200MHz square wave, t
r
< 300ps, 1.8Vp-p.
AC ELECTRICAL CHARACTERISTICS
5
SY88923AV
Micrel
Output Termination
The SY88923AV outputs must be terminated with a 50
load to V
CC
2V (or Thevenin equivalent).
Layout and PCB Design
Since the SY88923AV is a high-frequency component,
performance can largely be determined by board layout
and design. A common problem with high-gain amplifiers is
feedback from the large swing outputs to the input via the
power supply.
50
50
0.1
F
0.1
F
0.1
F
D
IN+
D
IN--
V
REF
V
CC
Figure 2. Differential Input Configuration
DESIGN PROCEDURE
General
The SY88923AV is an integrated limiting amplifier
intended for high-frequency fiber-optic applications. The
circuit connects to typical trans-impedance amplifiers found
within a fiber-optics link. The linear signal output from a
trans-impedance amplifier can contain significant amounts
GENERAL DESCRIPTION
of noise, and may vary in amplitude over time. The
SY88923AV limiting amplifier quantizes the signal and
outputs a voltage-limited waveform.
The /EN pin allows the user to disable the output signal
without removing the input signal.
The SY88923AV ground pin should be connected to the
circuit board ground. Use multiple PCB vias close to the
part to connect to ground. Avoid long, inductive runs which
can degrade performance.
R1
R2
V
CC
LOS
LVL
V
REF
Figure 3. LOS
LVL
Circuit
Note 1.
LOS
LVL
= V
CC
1.32V +
R1 + R2
2.6k
R2
1.32V
R1 + R2
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