1
SY88703V
Micrel, Inc.
M9999-072505
hbwhelp@micrel.com or (408) 955-1690
3.3V/5V 622Mbps PECL LOW-POWER
LIMITING POST AMPLIFIER W/TTL LOS
SY88703V
Rev.: B
Amendment: /0
Issue Date:
July 2005
TYPICAL APPLICATIONS CIRCUIT
APPLICATIONS
s
622Mbps SONET/SDH
s
Small form factor transceivers
s
High-gain line driver and line receiver
s
Single 3.3V or 5V power supply
s
Up to 622Mbps operation
s
Low noise PECL data outputs
s
Chatter-free TTL Loss-of-Signal (LOS) output
s
TTL /EN input
s
Programmable LOS level set (LOS
LVL
)
s
Available in a tiny 10-pin MSOP (3mm) package
FEATURES
DESCRIPTION
The SY88703V low-power limiting post amplifier is
designed for use in fiber optic receivers. The device connects
to typical transimpedance amplifiers (TIAs). The linear signal
output from TIAs can contain significant amounts of noise
and may vary in amplitude over time. The SY88703V
quantizes these signals and outputs PECL level waveforms.
The SY88703V operates from a single +3.3V or +5V
power supply, over temperatures ranging from 40
C to
+85
C. With its wide bandwidth and high gain, signals with
data rates up to 622Mbps and as small as 5mVp-p can be
amplified to drive devices with PECL inputs.
The SY88703V generates a TTL LOS output. A
programmable loss-of-signal level set pin (LOS
LVL
) sets the
sensitivity of the input amplitude detection. LOS asserts
high if the input amplitude falls below the threshold set by
LOS
LVL
and deasserts low otherwise. /EN deasserts the
true output signal without removing the input signal. Typically
4.6dB loss-of-signal hysteresis is provided to prevent
chattering.
V
CC
V
CC
/EN
GND
GND
To
CDR
SY88703V
3k
From
Transimpedance
Amp.
D
OUT
/D
OUT
V
REF
V
CC
LOS
LVL
D
IN
/D
IN
0.1
F
0.1
F
0.1
F
0.1
F
LOS
50
2k
50
100
R
pd
R
pd
For 3.3V, R
pd
= 120
For 5V, R
pd
= 220
2
SY88703V
Micrel, Inc.
M9999-072505
hbwhelp@micrel.com or (408) 955-1690
PIN DESCRIPTION
Pin Number
Pin Name
Type
Pin Function
1
/EN
TTL Input:
Enable: Deasserts true data output when high.
Default is high.
2
DIN
Data Input
True data input.
3
/DIN
Data Input
Complementary data input.
4
VREF
Reference voltage.
5
LOSLVL
Input
Loss-of-Signal Level Set: A voltage between V
CC
and V
REF
on this
pin sets the threshold for the data input amplitude at which LOS will be
asserted.
6
GND
Ground
Device ground.
7
LOS
Open-collector
Loss-of-Signal: Asserts high when the data input amplitude falls below
TTL Output
the threshold set by LOS
LVL
. Requires external pullup resistor.
8
/DOUT
PECL Output
Complementary data output.
9
DOUT
PECL Output
True data output.
10
VCC
Power Supply
Positive power supply.
LOSLVL
GND
6
5
1
/EN
DIN
/DIN
VREF
10 VCC
DOUT
/DOUT
LOS
9
8
7
2
3
4
10-Pin MSOP
(K10-1)
PACKAGE/ORDERING INFORMATION
Ordering Information
Package
Operating
Package
Lead
Part Number
Type
Range
Marking
Finish
SY88703VKC
K10-1
Commercial
703V
Sn-Pb
SY88703VKCTR
(1)
K10-1
Commercial
703V
Sn-Pb
SY88703VKG
K10-1
Industrial
703V with
Pb-Free
Pb-Free bar-line indicator
NiPdAu
SY88703VKGTR
(1)
K10-1
Industrial
703V with
Pb-Free
Pb-Free bar-line indicator
NiPdAu
Note:
1. Tape and Reel.
3
SY88703V
Micrel, Inc.
M9999-072505
hbwhelp@micrel.com or (408) 955-1690
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
CC
) ....................................... 0V to +7.0V
Input Voltage (D
IN
,
/D
IN
) ......................................... 0 to V
CC
Output Current (I
OUT
)
Continuous ............................................................. 50mA
Surge .................................................................... 100mA
/EN Voltage ............................................................ 0 to V
CC
V
REF
Current ......................................... 800
A to +500
A
LOS
LVL
Voltage ...................................................... 0 to V
CC
Lead Temperature (soldering, 20 sec.) ................... +260
C
Storage Temperature (T
S
) ....................... 55
C to +125
C
Operating Ratings
(Note 2)
Supply Voltage (V
CC
) .............................. +3.0V to +3.6V or
............................................................ +4.5V to +5.5V
Ambient Temperature (T
A
), Note 3 ............ 40
C to +85
C
Junction Temperature (T
J
), Note 3 .......... 40
C to +120
C
Package Thermal Resistance
MSOP
(
JA
) Still-Air .................................................. 113
C/W
(
JB
) Still-Air .................................................... 74
C/W
V
CC
= 3.0V to 3.6V or 4.5V to 5.5V; R
LOAD
= 50
to V
CC
2V; T
A
= 40
C to +85
C; typical values at V
CC
= 3.3V, T
A
= 25
C
Symbol
Parameter
Condition
Min
Typ
Max
Units
I
CC
Power Supply Current
no output load
25
42
mA
LOS
LVL
LOS
LVL
Voltage
V
REF
V
CC
V
V
IH
/EN Input HIGH Voltage
2.0
V
V
IL
/EN Input LOW Voltage
0.8
V
I
IH
/EN Input HIGH Current
V
IN
= 2.7V
20
A
V
IN
= V
CC
100
A
I
IL
/EN Input LOW Current
V
IN
= 0.5V
0.3
mA
V
OL
LOS Output LOW Level
I
OL
= +2mA
0.5
V
I
OH
LOS Output Leakage
V
OH
= 5.5V
250
A
V
OH
PECL Output HIGH Voltage
50
to V
CC
2V output load
V
CC
1.085 V
CC
0.955 V
CC
0.880
V
V
OL
PECL Output LOW Voltage
50
to V
CC
2V output load
V
CC
1.830 V
CC
1.705 V
CC
1.555
V
V
OFFSET
Differential Output Offset
100
mV
V
IHCMR
Common Mode Range
Note 2
GND +1.7
V
CC
V
V
REF
Reference Voltage
Note 3
V
CC
1.38
V
CC
1.32
V
CC
1.26
V
Note 1.
Specification for packaged product only.
Note 2.
The V
IHCMR
range is referenced to the most positive side of the differential input signal.
Note 3.
The current provided into or from V
REF
must be limited to 800
A source and 500
A sink.
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.
Note 3.
Commercial devices are guaranteed from 0
C to +85
C ambient temperature.
4
SY88703V
Micrel, Inc.
M9999-072505
hbwhelp@micrel.com or (408) 955-1690
V
CC
= 3.0V to 3.6V or 4.5V to 5.5V; R
LOAD
= 50
to V
CC
2V; T
A
= 40
C to +85
C; typical values at V
CC
= 3.3V, T
A
= 25
C.
Symbol
Parameter
Condition
Min
Typ
Max
Units
HYS
LOS Hysteresis
electrical signal
2
4.6
8
dB
t
OFF
LOS Release Time
0.1
0.5
s
t
ON
LOS Assert Time
0.2
0.5
s
t
r
,t
f
Differential Output Rise/Fall Time
400
ps
(20% to 80%)
V
ID
Differential Input Voltage Swing
5
1800
mVp-p
V
OD
Differential Output Voltage Swing
V
ID
18mVp-p
1500
mVp-p
V
ID
=
5mVp-p
400
mVp-p
V
SR
LOS Sensitivity Range
5
50
mVp-p
A
V(Diff)
Differential Voltage Gain
38
dB
B
3dB
3dB Bandwidth
700
MHz
S
21
Single-Ended Small-Signal Gain
26
32
dB
Note 1.
Specification for packaged product only.
AC ELECTRICAL CHARACTERISTICS
(Note 1)
TYPICAL OPERATING CHARACTERISTICS
0
10
20
30
40
50
60
70
80
90
100
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
V
ID
(mVp-p)
LOS
LVL
(referenced to V
CC
) (V)
3.3V LOS Assert and Deassert
Levels vs. LOS
LVL
3.3V
T
A
= 25
C
622Mbps
Pattern 2
23
-1
0
10
20
30
40
50
60
70
80
90
100
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
V
ID
(mVp-p)
LOS
LVL
(referenced to V
CC
) (V)
5V LOS Assert and Deassert
Levels vs. LOS
LVL
5.0V
T
A
= 25
C
622Mbps
Pattern 2
23
-1
5
SY88703V
Micrel, Inc.
M9999-072505
hbwhelp@micrel.com or (408) 955-1690
DETAILED DESCRIPTION
The SY88703V low power limiting post amplifier operates
from a single +3.3V or +5V power supply, over temperatures
from 40
C to +85
C. Signals with data rates up to 622Mbps
and as small as 5mVp-p can be amplified. Figure 1 shows
the allowed input voltage swing. The SY88703V generates
an LOS output. LOS
LVL
sets the sensitivity of the input
amplitude detection.
Input Amplifier/Buffer
Figure 2 shows a simplified schematic of the SY88703V's
input stage. The high-sensitivity of the input amplifier allows
signals as small as 5mVp-p to be detected and amplified.
The input amplifier allows input signals as large as
1800mVp-p. Input signals are linearly amplified with a
typically 38dB differential voltage gain. Since it is a limiting
amplifier, the SY88703V outputs typically 1500mVp-p
voltage-limited waveforms for input signals that are greater
than 18mVp-p. Applications requiring the SY88703V to
operate with high-gain should have the upstream TIA placed
as close as possible to the SY88703V's input pins to ensure
the best performance of the device.
Output Buffer
The SY88703V's PECL output buffer is designed to drive
50
lines. The output buffer requires appropriate termination
for proper operation. An external 50
resistor to V
CC
2V
for each output pin provides this. Figure 3 shows a simplified
schematic of the output stage and includes an appropriate
termination method.
Loss-of-Signal
The SY88703V generates a chatter-free TTL LOS. A
recommended 2k
pull-up resistor to V
CC
is required for
proper operation, as shown in Figure 4. LOS is used to
determine that the input amplitude is too small to be
considered a valid input. LOS asserts high if the input
amplitude falls below the threshold set by LOS
LVL
and
deasserts low otherwise. LOS can be fed back to the enable
(/EN) input to maintain output stability under a loss of signal
condition. /EN deasserts the true output signal without
removing the input signals. Typically 4.6dB LOS hysteresis
is provided to prevent chattering.
Loss-of-Signal Level Set
A programmable LOS level set pin (LOS
LVL
) sets the
threshold of the input amplitude detection. Setting a voltage
on LOS
LVL
between V
CC
and V
REF
sets this threshold. If
desired, a resistor divider between V
CC
and V
REF
, as shown
in Figure 5, also creates this threshold. The smaller the
voltage difference from LOS
LVL
to V
CC
, the smaller the
LOS sensitivity. Hence, larger input amplitude is required to
deassert LOS.
"Typical Operating Characteristics" shows
the relationship between the input amplitude detection
sensitivity and the LOS
LVL
voltage.
Hysteresis
The SY88703V provides typically 4.6dB LOS electrical
hysteresis. By definition, a power ratio measured in dB is
10log(power ratio). Power is calculated as V
2
IN
/R for an
electrical signal. Hence the same ratio can be stated as
20log(voltage ratio). While in linear mode, the electrical
voltage input changes linearly with the optical power and
hence the ratios change linearly. Therefore, the optical
hysteresis in dB is half the electrical hysteresis in dB given
in the datasheet. The SY88703V provides typically 2.3dB
LOS optical hysteresis. As the SY88703V is an electrical
device, this datasheet refers to hysteresis in electrical terms.
With 6dB LOS hysteresis, a voltage factor of two is required
to assert or deassert LOS.
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