SY88147DL
3.3V, 1.25Gbps PECL Limiting Post
Amplifier w/High Gain TTL Loss-of-Signal
February 2007
1 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
General Description
The SY88147DL is a high-sensitivity limiting post
amplifier designed for use in fiber-optic receivers. These
devices connect 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 SY88147DL quantizes these signals and
outputs PECL level waveforms.
The SY88147DL operates from a single +3.3V power
supply, over temperatures ranging from –40
o
C to +85
o
C.
With its wide bandwidth and high gain, signals with data
rates up to 1.25Gbps, and as small as 5mV
PP
, can be
amplified to drive devices with PECL inputs.
The SY88147DL generates a high-gain loss-of-signal
(LOS) open-collector TTL output. The LOS function has
a high gain input stage for increased sensitivity. 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 de-asserts low otherwise.
The enable bar input (/EN) de-asserts the true output
signal without removing the input signal. The LOS
output can be fed back to the /EN input to maintain
output stability under a loss-of-signal condition. Typically
3.5dB LOS hysteresis is provided to prevent chattering.
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
Features
• Single 3.3V power supply
• DC to 1.25Gbps operation
• Low-noise PECL data outputs
• High-gain LOS
• Chatter-free Open-Collector TTL Loss of Signal
(LOS) output with internal 4.75kΩ pull-up resistor
• TTL /EN input
• Programmable LOS level set (LOS
LVL
)
• Available in a tiny 10-pin MSOP
Applications
• APON/BPON/EPON/GEPON/GPON
• Gigabit Ethernet
• 531Mbps and 1062Mbps Fibre Channel
• OC-3 and OC-12/24 SONET/SDH
• High-gain line driver and line receiver
• Low-gain TIA interface
Markets
• FTTH
• Datacom/Telecom
• Optical transceiver
Micrel, Inc. SY88147DL
February 2007
2 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Typical Application Circuit
Micrel, Inc. SY88147DL
February 2007
3 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Ordering Information
Part Number Package
Type Operating
Range Package Marking Lead
Finish
SY88147DLKG K10-1 Industrial 147D with Pb-Free bar line indicator NiPdAu
Pb-Free
SY88147DLKGTR
(1)
K10-1 Industrial 147D with Pb-Free bar line indicator NiPdAu
Pb-Free
Note:
1. Tape and Reel.
Pin Configur ation
10-Pin MSOP (K10-1)
Pin Description
Pin Number Pin Name Type Pin Function
1 /EN
TTL Input: Default is
HIGH.
/Enable: This input enables the outputs when it is LOW. Note
that this input is internally connected to a 25kΩ pull-up resistor
and will default to a logic HIGH state if left open.
2 DIN Data Input True data input.
3 /DIN Data Input Complementary data input.
4 VREF Reference voltage: Placing a capacitor here to V
CC
helps
stabilize LOS
LVL
.
5 LOSLVL Input Loss-of-Signal Level Set: a resistor from this pin to V
CC
sets the
threshold for the data input amplitude at which LOS will be
asserted.
6 GND,
Exposed Pad
Ground Device ground.
7 LOS
Open-collector TTL
output w/internal 4.75kΩ
pull-up resistor
Loss-of-Signal: asserts high when the data input amplitude falls
below the threshold sets by LOS
LVL
.
8 /DOUT PECL Output Complementary data output.
9 DOUT PECL Output True data output.
10 VCC Power Supply Positive power supply.
Micrel, Inc. SY88147DL
February 2007
4 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Absolute Maximum Ratings(1)
Supply Voltage (V
CC
) ....................................... 0V to +4.0V
Input Voltage (DIN, /DIN) .......................................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................................................. V
REF
to V
CC
Lead Temperature (soldering, 20sec.) ................... +260°C
Storage Temperature (T
s
) ....................... –65°C to +150°C
Operating Ratings(2)
Supply Voltage (V
CC
)............................. +3.0V to +3.6V
Ambient Temperature (T
A
) ................... –40°C to +85°C
Junction Temperature (T
J
) ................. –40°C to +125°C
Junction Thermal Resistance
MSOP
(θ
JA
) Still-air.......................................... 113°C/W
DC Electrical Characteristics
V
CC
= 3.0 to 3.6V; R
L
= 50Ω 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 26 39 mA
LOS
LVL
LOS
LVL
Voltage V
REF
V
CC
V
V
OH
PECL Output HIGH Voltage V
CC
-1.085 V
CC
-0.955 V
CC
-0.880 V
V
OL
PECL Output LOW Voltage V
CC
-1.850 V
CC
-1.705 V
CC
-1.555 V
V
IHCMR
Common Mode Range GND+2.0 V
CC
V
V
REF
Reference Voltage V
CC
-1.48 V
CC
-1.32 V
CC
-1.16 V
TTL DC Electrical Characteristics
V
CC
= 3.0 to 3.6V; R
L
= 50Ω 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
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
V
IN
= V
CC
20
100
µA
µA
I
IL
/EN Input LOW Current V
IN
= 0.5V -0.3 mA
V
OH
LOS Output HIGH Level V
CC
> 3.3V, I
OH-MAX
< 160µA
V
CC
< 3.3V, I
OH-MAX
< 160µA
2.4
2.0
V
V
V
OL
LOS Output LOW Level I
OL
= +2mA 0.5 V
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 rating 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.
3. Thermal performance assumes the use of a 4-layer PCB. Exposed pad must be soldered (or equivalent) to the device’s most negative potential
on the PCB.
Micrel, Inc. SY88147DL
February 2007
5 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
AC Electrical Characteristics
V
CC
= 3.0V to 3.6V; R
LOAD
=50 to V
CC
–2V; T
A
= –40°C to +85°C.
Symbol Parameter Condition Min Typ Max Units
t
r
, t
f
Output Rise/Fall Time
(20% to 80%) Note 4 260 ps
t
JITTER
Deterministic
Random
Note 5
Note 6 15
5 ps
PP
ps
RMS
V
ID
Differential Input Voltage Swing Figure 1 5 1800 mv
PP
V
OD
Differential Output Voltage
Swing
V
ID
> 18mV
PP
Figure 1 1500 mv
PP
T
OFF
LOS Release Time 2 10 µs
T
ON
LOS Assert Time 2 10 µs
LOS
AL
Low LOS Assert Level R
LOSLVL
= 15kΩ, Note 8 2.3 mV
PP
LOS
DL
Low LOS De-assert Level R
LOSLVL
= 15kΩ, Note 8 3.4 mV
PP
HYS
L
Low LOS Hysteresis R
LOSLVL
= 15kΩ, Note 7 3.4 dB
LOS
AM
Medium LOS Assert Level R
LOSLVL
= 5kΩ, Note 8 4.2 mV
PP
LOS
DM
Medium LOS De-assert Level R
LOSLVL
= 5kΩ, Note 8 6.2 mV
PP
HYS
M
Medium LOS Hysteresis R
LOSLVL
= 5kΩ, Note 7 2 3.4 4.5 dB
LOS
AH
High LOS Assert Level R
LOSLVL
= 100Ω, Note 8 10.8 mV
PP
LOS
DH
High LOS De-assert Level R
LOSLVL
= 100Ω, Note 8 16.4 mV
PP
HYS
H
High LOS Hysteresis R
LOSLVL
= 100Ω, Note 7 2 3.6 4.5 dB
B
-3dB
3dB Bandwidth 1 GHz
A
V(Diff)
Differential Voltage Gain 42 dB
S
21
Single-ended Small-Signal Gain 30 36 dB
Notes:
4. Amplifier in limiting mode. Input is a 200MHz square wave.
5. Deterministic jitter measured using 1.25Gbps K28.5 pattern, V
ID
= 10mV
PP
.
6. Random jitter measured using 1.25Gbps K28.7 pattern, V
ID
= 10mV
PP
.
7. This specification defines electrical hysteresis as 20log (LOS De-assert/LOS Assert). The ratio between optical hysteresis and electrical
hysteresis is found to vary between 1.5 and 2 depending on the level of received optical power and ROSA characteristics. Based on that ratio,
the optical hysteresis corresponding to the electrical hysteresis range 2dB-4.5dB, shown in the AC characteristics table, will be 1dB-3dB.
8. See “Typical Operating Characteristics” for a graph showing how to choose a particular R
LOSLVL
for a particular LOS assert and its associated
de-assert amplitude.
Micrel, Inc. SY88147DL
February 2007
6 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Typical Operating Characteristics
V
CC
= 3.3V, T
A
= 25°C, R
L
= 50Ω to V
CC
–2V, unless otherwise stated.
Micrel, Inc. SY88147DL
February 2007
7 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Functional Block Diagram
Detailed Description
The SY88147DL high-sensitivity limiting post amplifier
operates from a single +3.3V power supply, over
temperatures from –40°C to +85°C. Signals with data
rates up to 1.25Gbps and as small as 5mV
PP
can be
amplified. Figure 1 shows the allowed input voltage
swing. The SY88147DL generates a LOS output,
allowing feedback to /EN for output stability. LOS
LVL
sets
the sensitivity of the input amplitude detection.
Input Amplifier/Buffer
Figure 2 shows a simplified schematic of the 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 42dB differential voltage gain. Since it is a
limiting amplifier, the SY88147DL outputs typically
1500mV
PP
voltage-limited waveforms for input signals
that are greater than 12mV
pp
. Applications requiring the
SY88147DL to operate with high-gain should have the
upstream TIA placed as close as possible to the
SY88147DL’s input pins to ensure the best performance
of the device.
Output Buffer
The SY88147DL’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.
Loss-of-Signal
The SY88147DL generates a chatter-free loss-of-signal
(LOS) open-collector TTL output with internal 4.75kΩ
pull-up resistor 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 sets by LOSLVL and
de-asserts low otherwise. LOS can be fed back to the
enable (/EN) input to maintain output stability under a
loss of signal condition. /EN de-asserts low the true
output signal without removing the input signals.
Typically, 3.5dB 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. Connecting
an external resistor between V
CC
and LOS
LVL
sets the
voltage at LOS
LVL
. This voltage 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.
Hysteresis
The SY88147DL typically provides 3.5dB 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 data sheet. The
SY88147DL is an electrical device; this data sheet
refers to hysteresis in electrical terms. With 3.5dB LOS
hysteresis, a voltage factor of 1.5 is required to assert or
de-assert LOS.
Micrel, Inc. SY88147DL
February 2007
8 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Figure 1. V
IS
and V
ID
Definition
Figure 2. Input Structure
Figure 3. Outpu t Stru cture
Figure 4. LOS Output Structure
Figure 5. LOS
LVL
Setting Circuit
Note: Recommended value for RLOSLVL is 15kΩ or less.
Micrel, Inc. SY88147DL
February 2007
9 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Related Product an d Support Documentation
Part Number Function Data Sheet Link
SY88903AL 3.3V/5V 1.25Gbps PECL High-Sensitivity
Limiting Post Amplifier with TTL LOS
http://www.micrel.com/product-info/sy88903al.shtml
Application Notes Notes on Sensitivity and Hysteresis in Micrel
Post Amplifiers
http://www.micrel.com/product-info/app_hints+notes.shtml
Micrel, Inc. SY88147DL
February 2007
10 M9999-021207-B
hbwhelp@micrel.com or (408) 955-1690
Package Information
10-Pin MSOP (K10-1)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for
its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a
product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for
surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant
injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk
and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Incorporated.
