Micrel, Inc.
5V/3.3V 1.25Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
SY88903V
SY88903V
FEATURES
■
■
■
■
■
3.3V and 5V power supply option
Up to 1.25Gbps operation
Low noise
Chatter-free LOS generation
Open collector TTL LOS output
DESCRIPTION
The SY88903V 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 5mV
pp
can be amplified to drive devices with
PECL inputs. The SY88903V generates a chatter-free, Loss-
-of-Signal (LOS), open-collector TTL output.
The SY88903V is an integrated limiting amplifier intended
for high-frequency fiber optic applications. The circuit
connects to typical transimpedance amplifiers found within
a fiber optics link. The linear signal output from a
transimpedance amplifier can contain significant amounts
of noise, and may vary in amplitude over time. The
SY88903V 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 SY88903V 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.
The sensitivity of the level detection can be adjusted using
LOS
LVL
. The LOS
LVL
voltage can be set by connecting a
resistor divider between V
CC
and V
REF
as shown in Figure
3. “Typical Characteristics” 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.
V
CC
SY88903V
LOS
2.5kΩ
■
TTL /EN Input
■
Differential PECL inputs for data
■
Single power supply
■
Designed for use with laser diode driver and
controller
■
Available in a tiny 10-pin (3mm
×
3mm) MSOP
APPLICATIONS
■
■
■
■
1.25Gbps Gigabit Ethernet
531Mbps and 1062Mbps Fibre Channel
622Mbps SONET
Gigabit Interface Converter
BLOCK DIAGRAM
D
IN
Limiting
Amplifer
ECL
Buffer
D
OUT
Figure 1. LOS Output with Desired Rise Time
D
OUT
D
IN
V
REF
Enable
All support documentation can be found on Micrel’s web
site at www.micrel.com.
V
CC
GND
Level
Detect
EN
LOS
LVL
LOS
M9999-111307
hbwhelp@micrel.com or (408) 955-1690
Rev.: F
Amendment: /0
1
Issue Date: November 2007
Micrel, Inc.
SY88903V
PACKAGE/ORDERING INFORMATION
Ordering Information
(1)
/EN 1
DIN 2
/DIN 3
VREF 4
LOSLVL 5
10 VCC
9 DOUT
8 /DOUT
7 LOS
6 GND
Part Number
SY88903VKC
SY88903VKCTR
(2)
SY88903VKG
SY88903VKGTR
(2)
Notes:
Package
Type
K10-1
K10-1
K10-1
K10-1
Operating
Range
Commercial
Commercial
Industrial
Industrial
Package
Marking
903V with
Pb-free bar-line indicator
903V with
Pb-free bar-line indicator
903V with
Pb-free bar-line indicator
903V with
Pb-free bar-line indicator
Lead
Finish
Sn-Pb
Sn-Pb
NiPdAu
Pb-Free
NiPdAu
Pb-Free
10-Pin MSOP (K10-1)
1. Contact factory for die availability. Die is guaranteed at T
A
= 25°C, DC electricals only.
2. Tape and Reel.
PIN DESCRIPTION
Pin Number
1
2
3
4
5
6
7
8
9
10
Pin Name
EN
DIN
/DIN
VREF
LOSLVL
GND
LOS
/DOUT
DOUT
VCC
Type
TTL Input
Data Input
Data Input
Output
Input
Ground
TTL Output
(Open Collector)
PECL Output
PECL Output
Power Supply
Pin Function
Output Enable (Active Low).
Data Input.
Inverting Data Input.
Reference Voltage Output for LOS Level Set (see Figure 3).
LOS Limit Set.
Ground
Loss-of-Signal Indicator (Active Low).
Inverting Data Output.
Data Output.
Positive Power Supply.
M9999-111307
hbwhelp@micrel.com or (408) 955-1690
2
Micrel, Inc.
SY88903V
Absolute Maximum Ratings
(1)
Supply Voltage (V
CC
) ....................................... 0V to +7.0V
Input Voltage (D
IN
, /D
IN
, /EN, LOS
LVL
) ............... 0V to V
CC
Output Voltage
(D
OUT
, /D
OUT
) with 50Ω Load ... V
CC
–2.5V to V
CC
+0.3V
(VREF) ............................................ V
CC
–2.0V to V
CC
Lead Temperature (soldering, 20 sec.) ..................... 260°C
Maximum Operating Junction Temperature (T
J
) ..... +125°C
Storage Temperature (T
S
) ....................... –55°C to +125°C
Operating Ratings
(2)
Supply Voltage (V
IN
) ................................. +2.97V to +5.5V
Ambient Temperature (T
A
) ......................... –40°C to +85°C
Package Thermal Resistance
MSOP
(θ
JA
) Still-air ........................................... 113°C/W
DC ELECTRICAL CHARACTERISTICS
V
CC
= +5V
±10%
or +3.3V
±10%;
R
LOAD
= 50Ω to V
CC
–2V; T
A
= –40°C to +85°C; unless noted.
Symbol
I
CC
I
IL
I
IH
V
CMR
V
OFFSET
LOS
LVL
V
OL
I
OH
V
OH
V
OL
V
REF
I
REF
V
IH
V
IL
Notes:
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 ratings conditions for extended
periods may affect device reliability.
2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
Parameter
Power Supply Current
/EN Input LOW Current
/EN Input HIGH Current
Common Mode Range
Differential Output Offset
LOSLVL Level
LOS Output Low Level
LOS Output Leakage
DOUT and /DOUT
HIGH Output
DOUT and /DOUT
LOW Output
Reference Supply
VREF Output Current
/EN Input HIGH Voltage
/EN Input LOW Voltage
Condition
No output load
V
IN
= 0.5V
V
IN
= 2.7V
V
IN
= VCC
Min
Typ
30
Max
42
Units
mA
mA
–0.3
20
100
GND +2.0
V
CC
±160
V
REF
V
CC
0.5
250
V
CC
–1085 V
CC
–955
V
CC
–880
µA
V
mV
V
V
µA
mV
mV
V
mA
V
I
OL
= +2mA
V
OH
= 5.5V
V
CC
–1830 V
CC
–1705 V
CC
–1620
V
CC
–1.38 V
CC
–1.32 V
CC
–1.26
–0.8
2.0
0.8
0.5
V
M9999-111307
hbwhelp@micrel.com or (408) 955-1690
3
Micrel, Inc.
SY88903V
AC ELECTRICAL CHARACTERISTICS
V
CC
= +5V
±10%
or +3.3V
±10%;
R
LOAD
= 50Ω to V
CC
–2V; T
A
= –40°C to +85°C; unless noted.
Symbol
PSRR
V
ID
t
r
, t
f
V
OD
t
OFFL
t
OFFH
t
ONL
VSR
HYS
Parameter
Power Supply
(3)
Rejection Ratio
Input Voltage Range
Output Rise/Fall Time
Differential Output
Voltage Swing
(4)
LOS Release Time
(5)
Minimum Input
LOS Release Time
(6)
Maximum Input
LOS Assert Time
(5)
LOS Sensitivity Range
LOS Hysteresis
2
23
–1 pattern
2
23
–1 pattern
5
2
4.6
V
ID
> 100mV
pp
V
ID
< 100mV
pp
V
ID
= 15mV
pp
V
ID
= 5mV
pp
Condition
Input referred, 55MHz
5
trin,tfin
600
200
0.1
0.1
0.2
0.5
0.5
0.5
50
8
mV
mV
µs
µs
µs
mV
pp
dB
Min
Typ
35
1800
260
Max
Units
dB
mV
pp
ps
Notes:
3. Input referred noise = RMS output noise/low frequency gain.
4. Input is a 622MHz square wave.
5. Input is a 200MHz square wave, t
r
< 300ps, 8mV
pp
.
6. Input is a 200MHz square wave, t
r
< 300ps, 1.8V
pp
.
TYPICAL CHARACTERISTICS
100
LOS Assert and De-assert
Levels vs LOS
LVL
INPUT LEVEL (mV
pp
)
3.3V
T
A
= 25°C
1.25Gbps
Pattern 2
7
-1
100
90
80
70
60
50
40
30
20
10
0
LOS Assert and De-assert
Levels vs LOS
LVL
5.0V
T
A
= 25°C
1.25Gbps
Pattern 2
7
-1
INPUT LEVEL (mV
pp
)
90
80
70
60
50
40
30
20
10
0
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
LOSLVL V
CC
– V
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
LOSLVL V
CC
– V
M9999-111307
hbwhelp@micrel.com or (408) 955-1690
4
Micrel, Inc.
SY88903V
DESIGN PROCEDURE
Output Termination
The SY88903V outputs must be terminated with a 50Ω
load to V
CC
–2V (or Thevenin equivalent).
Layout and PCB Design
Since the SY88903V 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.
The SY88903V 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.
V
CC
R1
LOS
LVL
0.1µF
0.1µF
50Ω
D
IN+
D
IN–
50Ω
V
REF
R2
V
REF
0.1µF
Notes:
R1
LOS
LVS
= V
CC
-1.32V x R1 + R2
R1 + R2
≥
2.6kΩ
Figure 2. Differential Input Configuration
Figure 3. LOSLVL Circut
M9999-111307
hbwhelp@micrel.com or (408) 955-1690
5
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