Micrel, Inc.
3.3V/5V 1.25Gbps PECL LOW-POWER
LIMITING POST AMPLIFIER
WITH TTL SIGNAL DETECT
DESCRIPTION
SY88933V
SY88933V
FEATURES
■
Single 3.3V or 5V power supply
■
DC to 1.25Gbps operation
■
Low noise PECL data outputs
■
Chatter-free OC-TTL signal setect (SD) output with
internal 6.75k
Ω
pull-up resistor
■
TTL EN input
■
Programmable SD level set (SD
LVL
)
■
Available in a tiny 10-pin MSOP (3mm) package
The SY88933V 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 SY88933V quantizes these signals and outputs PECL
level waveforms.
The SY88933V 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 1.25Gbps and as small as 5mVp-p
can be amplified to drive devices with PECL inputs.
The SY88933V generates a TTL SD output. A
programmable signal-detect level set pin (SD
LVL
) sets
the sensitivity of the input amplitude detection. SD asserts
high if the input amplitude rises above the threshold set
by SD
LVL
and deasserts low otherwise. EN deasserts
the true output signal without removing the input signal.
Typically, 4.6dB SD hysteresis is provided to prevent
chattering.
APPLICATIONS
■
■
■
■
■
1.25Gbps Ethernet
1.55Mbps and 622Mbps SONET/SDH
High-gain line driver and line receiver
531Mbps and 1062Mbps Fibre Channel
Gigabit interface converter
TYPICAL APPLICATIONS CIRCUIT
V
CC
SD
From
Transimpedance
Amp.
0.1µF
0.1µF
50Ω
D
IN
/D
IN
50Ω
EN
D
OUT
0.1µF
0.1µF
R
pd
SY88933V
SD
LVL
V
REF
/D
OUT
R
pd
To
CDR
GND
V
CC
100kΩ
0.1µF
GND
For 3.3V, R
pd
= 120Ω
For 5V, R
pd
= 220Ω
M9999-011508
hbwhelp@micrel.com or (408) 955-1690
Rev.: D
Amendment: /0
1
Issue Date: January 2008
Micrel, Inc.
SY88933V
PACKAGE/ORDERING INFORMATION
Ordering Information
EN 1
DIN 2
/DIN 3
VREF 4
SDLVL 5
10 VCC
9 DOUT
8 /DOUT
7 SD
6 GND
Part Number
SY88933VKC
SY88933VKCTR
(1)
SY88933VKI
SY88933VKITR
(1)
SY88933VKG
(2)
SY88933VKGTR
(1, 2)
Note:
1.
2.
Tape and Reel.
Package
Type
K10-1
K10-1
K10-1
K10-1
K10-1
K10-1
Operating
Range
Commercial
Commercial
Industrial
Industrial
Industrial
Industrial
Package
Marking
933V
933V
933V
933V
933V with
Pb-Free bar-line indicator
933V with
Pb-Free bar-line indicator
Lead
Finish
Sn-Pb
Sn-Pb
Sn-Pb
Sn-Pb
Pb-Free
NiPdAu
Pb-Free
NiPdAu
10-Pin MSOP (K10-1)
Pb-Free package is recommended for new designs.
PIN DESCRIPTION
Pin Number
1
2
3
4
5
6
7
Pin Name
EN
DIN
/DIN
VREF
SDLVL
GND
SD
Input
Ground
Open-collector
TTL output w/
internal 6.75kΩ
pull-up resistor
PECL Output
PECL Output
Power Supply
Type
TTL Input:
Default is high.
Data Input
Data Input
Pin Function
Enable: Asserts true data output when high.
True data input.
Complementary data input.
Reference voltage: capacitor here to V
CC
helps stabilize SD
LVL
.
Signal-Detect Level Set: a resistor from this pin to V
CC
sets the
threshold for the data input amplitude at which SD will be asserted.
Device ground.
Signal-Detect: asserts high when the data input amplitude rises above
the threshold set by SD
LVL
.
8
9
10
/DOUT
DOUT
VCC
Complementary data output.
True data output.
Positive power supply.
M9999-011508
hbwhelp@micrel.com or (408) 955-1690
2
Micrel, Inc.
SY88933V
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
SD
LVL
Voltage ................................................. V
REF
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
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
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
SD
LVL
V
IH
V
IL
I
IH
I
IL
V
OH
V
OL
V
OH
V
OL
V
OFFSET
V
IHCMR
V
REF
Note 1.
Note 2.
Parameter
Power Supply Current
SD
LVL
Voltage
EN Input HIGH Voltage
EN Input LOW Voltage
EN Input HIGH Current
EN Input LOW Current
SD Output HIGH Level
SD Output LOW Level
PECL Output HIGH Voltage
PECL Output LOW Voltage
Differential Output Offset
Common Mode Range
Reference Voltage
Condition
No output load
Min
Typ
22
Max
42
V
CC
0.8
Units
mA
V
V
V
µA
µA
mA
V
V
V
REF
2.0
V
IN
= 2.7V
V
IN
= V
CC
V
IN
= 0.5V
V
CC
≥
3.3V
V
CC
< 3.3V
I
OL
= +2mA
50Ω to V
CC
–2V output load
50Ω to V
CC
–2V output load
Note 1
Note 2
–0.3
2.4
2.0
20
100
0.5
V
CC
–1.085 V
CC
–0.955 V
CC
–0.880
V
CC
–1.830 V
CC
–1.705 V
CC
–1.555
±160
GND +2.0
V
CC
–1.38
V
CC
–1.32
V
CC
V
CC
–1.26
V
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.
M9999-011508
hbwhelp@micrel.com or (408) 955-1690
3
Micrel, Inc.
SY88933V
AC ELECTRICAL CHARACTERISTICS
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
V
ID
V
OD
V
SR
A
V(Diff)
B
–3dB
S
21
t
r
, t
f
Parameter
SD Hysteresis
SD Release Time
SD Assert Time
Differential Input Voltage Swing
Differential Output Voltage Swing
SD Sensitivity Range
Differential Voltage Gain
3dB Bandwidth
Single-Ended Small-Signal Gain
Differential Output Rise/Fall Time
(20% to 80%)
V
ID
> 100mV
PP
and 50Ω to V
CC
– 2V load
1
26
32
260
V
ID
≥
18mV
PP
V
ID
= 5mV
PP
5
38
5
1500
400
50
Condition
electrical signal
Min
2
Typ
4.6
0.1
0.2
Max
8
0.5
0.5
1800
Units
dB
µs
µs
mV
PP
mV
PP
mV
PP
mV
PP
dB
GHz
dB
ps
TYPICAL OPERATING CHARACTERISTICS
120
100
V
ID
(mVp-p)
80
60
SD Assert and Deassert
Levels vs. SD
LVL
V
SUP
= 3.3V
T
A
= 25°C
1.25Gbps
Pattern 2
23
–1
140
120
100
V
ID
(mVp-p)
80
60
40
SD Assert and Deassert
Levels vs. R
SDLVL
V
SUP
= 3.3V
T
A
= 25°C
1.25Gbps
Pattern 2
23
–1
ASSERT
ASSERT
40
20
DEASSERT
20
1
1.2 1.4
1
0
DEASSERT
0
10000
10
1000
SD
LVL
(referenced to V
CC
) (V)
R
SDLVL
(Ω)
M9999-011508
hbwhelp@micrel.com or (408) 955-1690
4
100000
100
0
0.2 0.4 0.6 0.8
Micrel, Inc.
SY88933V
DETAILED DESCRIPTION
The SY88933V 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 1.25Gbps and as small as 5mVp-p can be
amplified. Figure 1 shows the allowed input voltage swing.
The SY88933V generates an SD output. SD
LVL
sets the
sensitivity of the input amplitude detection.
Input Amplifier/Buffer
Figure 2 shows a simplified schematic of the
SY88933V's input stage. The high-sensitivity of the input
amplifier allows signals as small as 5mV
PP
to be detected
and amplified. The input amplifier allows input signals as
large
as
1800mV
PP
. Input signals are linearly amplified with a
typically 38dB differential voltage gain. Since it is a limiting
amplifier, the SY88933V outputs typically 1500mV
PP
voltage-limited waveforms for input signals that are
greater than 18mV
PP
. Applications requiring the
SY88933V to operate with high-gain should have the
upstream TIA placed as close as possible to the
SY88933V’s input pins to ensure the best performance
of the device.
Output Buffer
The SY88933V’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.
Signal-Detect
The SY88933V generates a chatter-free SD open-
collector TTL output with internal 6.75kΩ pullup resistor
as shown in Figure 4. SD is used to determine that the
input amplitude is large enough to be considered a valid
input. SD asserts high if the input amplitude rises above
the threshold set by SD
LVL
and deasserts low otherwise.
SD 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 SD hysteresis is provided
to prevent chattering.
Signal-Detect Level Set
A programmable SD level set pin (SD
LVL
) sets the
threshold of the input amplitude detection. Connecting
an external resistor between V
CC
and SD
LVL
sets the
voltage at SD
LVL
. This voltages ranges from V
CC
to V
REF
.
The external resistor creates a voltage divider between
V
CC
and V
REF
as shown in Figure 5. If desired, an
appropriate external voltage may be applied rather than
using a resistor. The smaller the external resistor, implying
a smaller voltage difference from SD
LVL
to V
CC
, the
smaller the SD sensitivity. Hence, larger input amplitude
is required to assert SD. “Typical Operating
Characteristics” shows the relationship between the input
amplitude detection sensitivity and the SD
LVL
voltage.
Hysteresis
The SY88933V provides typically 4.6dB SD 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 SY88933V provides typically
2.3dB SD optical hysteresis. As the SY88933V is an
electrical device, this datasheet refers to hysteresis in
electrical terms. With 6dB SD hysteresis, a voltage factor
of two is required to assert or deassert SD.
M9999-011508
hbwhelp@micrel.com or (408) 955-1690
5
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