DESCRIPTION
s
> 3.2Gbps operation
s
3.3V or 5V power supply option
s
Low noise CML data outputs
s
Chatter-Free LOS generation
s
Open Collector TTL LOS output
s
TTL /EN Input
s
Differential PECL inputs for data
s
Single power supply
s
Available in a tiny 10-pin (3mm) MSOP
The SY88993V limiting post amplifier with its high 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 4mVp-p can be amplified to drive devices with
CML inputs. The SY88993V generates a chatter-free Loss
of Signal (LOS) open collector TTL output.
The SY88993V 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 LOS
LVL
pin the sensitivity of the level detect can be
adjusted. The LOS
LVL
voltage can be set by connecting a
resistor divider between V
CC
and V
REF
, Figure 2.
FEATURES
5V/3.3V 3.2Gbps HIGH-SPEED
LIMITING POST AMPLIFIER
SY88993V
APPLICATIONS
s
1.25Gbps Gigabit Ethernet
s
531Mbps and 1062Mbps Fibre Channel
s
622Mbps SONET
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Gigabit interface converter
s
2.5Gbps SDH/SONET
PIN CONFIGURATION
BLOCK DIAGRAM
1
/EN
D
IN
/D
IN
V
REF
LOS
LVL
10 V
CC
D
OUT
/D
OUT
LOS
GND
9
8
7
6
2
3
4
5
MSOP
K10-1
Limiting
Amplifer
CML
Buffer
D
IN
D
IN
V
REF
V
CC
GND
LOS
LVL
Enable
Level
Detect
D
OUT
D
OUT
EN
LOS
1
Rev.: A
Amendment: /1
Issue Date: July 2000
2
SY88993V
Micrel
General
The SY88993V 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
SY88993V 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.
GENERAL DESCRIPTION
Symbol
Rating
Value
Unit
V
CC
Power Supply Voltage
0 to +7.0
V
D
IN
, /D
IN
Input Voltage
0 to V
CC
V
T
A
Operating Temperature Range
40 to +85
C
T
store
Storage Temperature Range
55 to +125
C
ABSOLUTE MAXIMUM RATINGS
(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.
Pin
Type
Function
D
IN
Data Input
Data Input
/D
IN
Data Input
Inverting Data Input
LOS
LVL
Input
Loss of Signal Level Set
/EN
TTL Input
Output Enable (Active Low)
LOS
TTL Output
Loss of Signal Indicator
(Open Collector)
(Active High)
GND
Ground
Ground
D
OUT
CML Output
Data Output
/D
OUT
CML Output
Inverting Data Output
V
CC
Power Supply
Positive Power Supply
V
REF
Output
Reference Voltage Output
for LOS Level Set (see Fig. 3)
PIN NAMES
3
SY88993V
Micrel
T
A
= 40
C
T
A
= 0
C
T
A
= +25
C
T
A
= +85
C
Symbol
Parameter
Min.
Max.
Min.
Max.
Min.
Typ.
Max.
Min.
Max.
Unit
I
CC
Power Supply
5V
--
40
--
40
--
34
40
--
45
mA
Current
(1)
3.3V
--
35
--
35
--
30
35
--
40
mA
I
IL
/EN Input LOW0.3
(8)
--
0.3
(6)
--
0.3
(6)
--
--
0.3
(8)
--
mA
Current
I
IH
/EN Input HIGH
--
20
(4)
--
20
(4)
--
--
20
(4)
--
20
(4)
A
Current
--
100
(5)
--
100
(5)
--
--
100
(5)
--
100
(5)
I
OH
LOS Output Leakage
(2)
--
100
--
100
--
--
100
--
100
uA
LOS
LVL
LOS
LVL
Level
V
REF
V
CC
V
REF
V
CC
V
REF
--
V
CC
V
REF
V
CC
V
V
OL
LOS Output Low
--
0.5
--
0.5
--
--
0.5
--
0.5
V
Level
(3)
V
REF
Reference Voltage
V
CC
1.38 V
CC
1.26 V
CC
1.38
V
CC
1.26
V
CC
1.38
V
CC
1.32
V
CC
1.26
V
CC
1.38 V
CC
1.26
V
V
IH
/EN Input HIGH Voltage
2.0
--
2.0
--
2.0
--
--
2.0
--
V
V
IL
/EN Input LOW Voltage
--
--
0.8
--
0.8
--
--
0.8
--
V
V
OFFSET
Differential Output
--
80
--
80
--
10
80
--
80
mV
Offset
V
CMR
Common Mode Range
GND
2 V
CC
0.2
GND
2
V
CC
0.2
GND
2
V
CC
0.2
GND
2
V
CC
0.2
V
DC ELECTRICAL CHARACTERISTICS
V
CC
= +3.3V
10% or +5V
10%, R
LOAD
= 50
to V
CC
NOTES:
1. No output load.
2. V
OH
= 5.5V.
3. I
OL
= +2mA.
4. V
IN
= 2.7V
5. V
IN
= V
CC
6. V
IN
= 0.5V
4
SY88993V
Micrel
AC ELECTRICAL CHARACTERISTICS
V
CC
= +3.3V
10% or +5V
10%, R
LOAD
= 50
to V
CC
T
A
= 40
C
T
A
= 0
C
T
A
= +25
C
T
A
= +85
C
Symbol
Parameter
Min.
Max.
Min.
Max.
Min.
Typ.
Max.
Min.
Max.
Unit
HYS
LOS Hysteresis
2
8
2
8
2
5.6
8
2
8
dB
PSRR
Power Supply
(1)
--
--
--
--
--
35
--
--
--
dB
Rejection Ratio
t
OFFL
LOS Release Time
(2)
--
0.5
--
0.5
--
0.1
0.5
--
0.5
s
Minimum Input
t
OFFH
LOS Release Time
(3)
--
0.5
--
0.5
--
0.1
0.5
--
0.5
s
Maximum Input
t
ONL
LOS Assert Time
(2)
--
0.5
--
0.5
--
0.2
0.5
--
0.5
s
t
r
, t
f
Differential Output
(3)
--
120
--
120
--
70
120
--
120
ps
Rise/Fall Time
V
ID
Input Voltage Range
4
1800
4
1800
4
--
1800
4
1800
mVp-p
V
OD
Differential Output
--
--
--
--
--
400
(5)
--
--
--
mVp-p
Voltage Swing
(4)
V
SR
LOS Sensitivity Range
4
50
4
50
4
--
50
4
50
mVp-p
Output Spec (D
OUT
and /D
OUT
)
V
OH
HIGH Level Output
V
CC
20
V
CC
V
CC
20
V
CC
V
CC
20
V
CC
5
V
CC
V
CC
20
V
CC
mV
Voltage
V
OL
LOW Level Output
(6)
V
CC
280 V
CC
140
V
CC
280
V
CC
140
V
CC
280
V
CC
200
V
CC
140
V
CC
280
V
CC
140
mV
Voltage
Z
O
Single-Ended Output
(7)
40
60
40
60
40
50
60
40
60
Impedance
Input Spec (D
IN
and /D
IN
)
A
V(Diff)
Differential Voltage
--
--
--
--
--
38
--
--
--
dB
Gain
B
3dB
3dB Bandwidth
--
--
--
--
--
2.5
--
--
--
GHz
S
21
Single-Ended Small
26
--
26
--
26
32
--
26
--
dB
Signal-Gain
NOTES:
1. Input referred noise = RMS output noise/low frequency gain. Input referred, 55MHz.
2. Input is a 200MHz square wave, t
r
< 300ps, 1.8Vp-p.
3. With input signal V
ID
> 5mVp-p.
4. Input is a 200MHz square wave, t
r
< 300ps, 50
load.
5. V
ID
> 5mVp-p.
6. Output levels are based on 50
impedance. If the load impedance is different, the output level will be changed.
7. See output structure.
5
SY88993V
Micrel
PRODUCT ORDERING CODE
Ordering
Package
Operating
Code
Type
Range
SY88993VKC
K10-1
Commercial
Output Termination
The SY88993V outputs must be terminated with a 50
load to V
CC.
Layout and PCB Design
Since the SY88993V 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 power
supply.
The SY88993V 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.
APPLICATION NOTE
Figure 3. LOS
LVL
Circuit
NOTES:
1. Resistor Divider = R2/ (R1 + R2)
2. R1 + R2
5k
Figure 2. Differential Output Configuration
Figure 1. Differential Input Configuration
R1
R2
V
CC
V
REF
LOS
LVL
GND
V
CC
22nF
22nF
ESD STRUCTURE
50
D
IN
/D
IN
50
V
REF
0.1
F
50
GND
V
CC
8mA
/D
OUT
Z
0
= 50
Z
0
= 50
V
CC
50
50
50
ESD STRUCTURE
D
OUT
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