Micrel
3.3V/5V 622Mbps PECL LOW-POWER
LIMITING POST AMPLIFIER W/TTL LOS
SY88703V
SY88703V
FEATURES
s
s
s
s
s
Single 3.3V or 5V power supply
Up to 622Mbps operation
Low noise PECL data outputs
Chatter-free TTL Loss-of-Signal (LOS) output
TTL /EN input
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.
s
Programmable LOS level set (LOS
LVL
)
s
Available in a tiny 10-pin MSOP (3mm) package
APPLICATIONS
s
622Mbps SONET/SDH
s
Small form factor transceivers
s
High-gain line driver and line receiver
TYPICAL APPLICATIONS CIRCUIT
V
CC
2kΩ
V
CC
LOS
From
Transimpedance
Amp.
0.1µF
0.1µF
50Ω
D
IN
/D
IN
50Ω
/EN
D
OUT
0.1µF
0.1µF
R
pd
SY88703V
LOS
LVL
V
CC
V
REF
/D
OUT
R
pd
To
CDR
GND
100Ω
3kΩ
GND
For 3.3V, R
pd
= 120Ω
For 5V, R
pd
= 220Ω
Rev.: A
Amendment: /0
1
Issue Date: March 2003
Micrel
SY88703V
PACKAGE/ORDERING INFORMATION
Ordering Information
/EN 1
DIN 2
/DIN 3
VREF 4
LOSLVL 5
10 VCC
9 DOUT
8 /DOUT
7 LOS
6 GND
Part Number
SY88703VKC
SY88703VKCTR*
SY88703VKI
SY88703VKITR*
*Tape and Reel
Package
Type
K10-1
K10-1
K10-1
K10-1
Operating
Range
Commercial
Commercial
Industrial
Industrial
Package
Marking
703V
703V
703V
703V
10-Pin MSOP
(K10-1)
PIN DESCRIPTION
Pin Number
1
2
3
4
5
Pin Name
/EN
DIN
/DIN
VREF
LOSLVL
Input
Type
TTL Input:
Default is high.
Data Input
Data Input
Pin Function
Enable: Deasserts true data output when high.
True data input.
Complementary data input.
Reference voltage.
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.
Device ground.
Loss-of-Signal: Asserts high when the data input amplitude falls below
the threshold set by LOS
LVL
. Requires external pullup resistor.
Complementary data output.
True data output.
Positive power supply.
6
7
8
9
10
GND
LOS
/DOUT
DOUT
VCC
Ground
Open-collector
TTL Output
PECL Output
PECL Output
Power Supply
2
Micrel
SY88703V
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 ......................................... –800µA to +500µA
LOS
LVL
Voltage ......................................................0 to V
CC
Storage Temperature (T
S
) ....................... –55°C to +125°C
Note 1.
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
(θ
JA
) Still-Air .................................................. 113°C/W
(ψ
JB
) Still-Air .................................................... 74°C/W
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.
The data sheet limits are not guaranteed if the device is operated beyond the operating ratings.
Commercial devices are guaranteed from 0°C to +85°C ambient temperature.
Note 2.
Note 3.
DC ELECTRICAL CHARACTERISTICS
(Note 1)
V
CC
= 3.0V to 3.6V or 4.5V to 5.5V; R
LOAD
= 50Ω to V
CC
–2V; T
A
= –40°C to +85°C; typical values at V
CC
= 3.3V, T
A
= 25°C
Symbol
I
CC
LOS
LVL
V
IH
V
IL
I
IH
I
IL
V
OL
I
OH
V
OH
V
OL
V
OFFSET
V
IHCMR
V
REF
Note 1.
Note 2.
Note 3.
Parameter
Power Supply Current
LOS
LVL
Voltage
/EN Input HIGH Voltage
/EN Input LOW Voltage
/EN Input HIGH Current
/EN Input LOW Current
LOS Output LOW Level
LOS Output Leakage
PECL Output HIGH Voltage
PECL Output LOW Voltage
Differential Output Offset
Common Mode Range
Reference Voltage
Specification for packaged product only.
Condition
no output load
Min
Typ
25
Max
42
V
CC
0.8
Units
mA
V
V
V
µA
µA
mA
V
REF
2.0
V
IN
= 2.7V
V
IN
= V
CC
V
IN
= 0.5V
I
OL
= +2mA
V
OH
= 5.5V
50Ω to V
CC
–2V output load
50Ω to V
CC
–2V output load
Note 2
Note 3
–0.3
20
100
0.5
250
V
CC
–1.085 V
CC
–0.955 V
CC
–0.880
V
CC
–1.830 V
CC
–1.705 V
CC
–1.555
±100
GND +1.7
V
CC
–1.38
V
CC
–1.32
V
CC
V
CC
–1.26
V
µA
V
V
mV
V
V
The V
IHCMR
range is referenced to the most positive side of the differential input signal.
The current provided into or from V
REF
must be limited to 800µA source and 500µA sink.
3
Micrel
SY88703V
AC ELECTRICAL CHARACTERISTICS
(Note 1)
V
CC
= 3.0V to 3.6V or 4.5V to 5.5V; R
LOAD
= 50Ω to V
CC
–2V; T
A
= –40°C to +85°C; typical values at V
CC
= 3.3V, T
A
= 25°C.
Symbol
HYS
t
OFF
t
ON
t
r
,t
f
V
ID
V
OD
V
SR
A
V(Diff)
B
–3dB
S
21
Note 1.
Parameter
LOS Hysteresis
LOS Release Time
LOS Assert Time
Differential Output Rise/Fall Time
(20% to 80%)
Differential Input Voltage Swing
Differential Output Voltage Swing
LOS Sensitivity Range
Differential Voltage Gain
3dB Bandwidth
Single-Ended Small-Signal Gain
Specification for packaged product only.
Condition
electrical signal
Min
2
Typ
4.6
0.1
0.2
Max
8
0.5
0.5
400
Units
dB
µs
µs
ps
mVp-p
mVp-p
mVp-p
5
V
ID
≥
18mVp-p
V
ID
=
5mVp-p
5
38
700
26
32
1500
400
1800
50
mVp-p
dB
MHz
dB
TYPICAL OPERATING CHARACTERISTICS
100
3.3V LOS Assert and Deassert
Levels vs. LOS
LVL
3.3V
T
A
= 25°C
622Mbps
Pattern 2
23
-1
90
80
70
60
50
40
30
20
10
0
0
100
90
80
70
60
50
40
30
20
10
0
5V LOS Assert and Deassert
Levels vs. LOS
LVL
5.0V
T
A
= 25°C
622Mbps
Pattern 2
23
-1
V
ID
(mVp-p)
V
ID
(mVp-p)
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
LOS
LVL
(referenced to V
CC
) (V)
0
-0.2 -0.4 -0.6 -0.8 -1.0 -1.2
LOS
LVL
(referenced to V
CC
) (V)
4
Micrel
SY88703V
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
50Ω lines. The output buffer requires appropriate termination
for proper operation. An external 50Ω 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 2kΩ 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
2IN
/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.
5
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