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SY88903AL
3.3V, Burst Mode 1.25Gbps PECL HighSensitivity Limiting Post Amplifier with TTL Loss-of-Signal
General Description
The SY88903AL, burst mode, high-sensitivity limiting post amplifier is designed for use in fiber-optic receivers, specially optimized for passive optical networks (PONs). 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 SY88903AL quantizes these signals and outputs PECL level waveforms. The SY88903AL operates from a single +3.3V power supply, over temperatures ranging from -40oC to +85oC. Signals with data rates from 622Mbps up to 1.25Gbps, and as small as 5mVpp, can be amplified to drive devices with PECL inputs. The SY88903AL generates a Loss-of-Signal (LOS) open-collector TTL output. A programmable Loss-ofSignal level set pin (LOSLVL) sets the sensitivity of the input amplitude detection. LOS asserts high if the input amplitude falls below the threshold set by LOSLVL 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, 3.4dB 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 * Fast LOS release/assert (<500ns) time for PON applications * 622Mbps to 1.25Gbps operation * Low-noise PECL data outputs * High gain LOS * Chatter-free Open-Collector TTL signal detect (LOS) output with internal 4.75k pull-up resistor * TTL /EN input * Programmable LOS level set (LOSLVL) * Available in a tiny 10-pin MSOP package
Applications
* * * * * GPON/GEPON/EPON Gigabit Ethernet, 1062Mbps Fibre Channel OC-12/24 SONET/SDH Low-gain TIA interface High-gain line driver and line receiver
Markets
* FTTH/FTTP * Datacom/telecom * Optical transceiver
February 2007
1
M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88903AL
Typical Application Circuit
February 2007
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M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88903AL
Ordering Information
Part Number SY88903ALKG SY88903ALKGTR(1)
Note: 1. Tape and Reel.
Package Type K10-1 K10-1
Operating Range Industrial Industrial
Package Marking 903A with Pb-Free bar line indicator 903A with Pb-Free bar line indicator
Lead Finish NiPdAu Pb-Free NiPdAu Pb-Free
Pin Configuration
10-Pin MSOP (K10-1)
Pin Description
Pin Number 1 Pin Name /EN Type TTL Input: Default is HIGH. Data Input Data Input Pin Function /Enable: This input enables the outputs when it is LOW. Note that this input is internally connected to a 25k pull-up resistor and will default to a logic HIGH state if left open. True data input. Complementary data input. Reference voltage: Placing a capacitor here to VCC helps stabilize LOSLVL. Input Loss-of-Signal Level Set: a resistor from this pin to VCC 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 LOSLVL. Complementary data output. True data output. Positive power supply.
2 3 4 5
DIN /DIN VREF LOSLVL
6 7
GND LOS
Ground Open-collector TTL output w/internal 4.75k pull-up resistor PECL Output PECL Output Power Supply
8 9 10
/DOUT DOUT VCC
February 2007
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Micrel, Inc.
SY88903AL
Absolute Maximum Ratings(1)
Supply Voltage (VCC) ....................................... 0V to +7.0V Input Voltage (DIN, /DIN) .......................................0 to VCC Output Current (IOUT) Continuous........................................................ 50mA Surge .............................................................. 100mA /EN Voltage ............................................................0 to VCC VREF Current .......................................... -800A to +500A LOSLVL Voltage................................................. VREF to VCC Lead Temperature (soldering, 20sec.) ..................... 260C Storage Temperature (Ts) ....................... -65C to +150C
Operating Ratings(2)
Supply Voltage (VCC)............................. +3.0V to +3.6V Ambient Temperature (TA) ................... -40C to +85C Junction Temperature (TJ) ................. -40C to +120C Junction Thermal Resistance MSOP (JA) Still-air ................................... 113C/W
DC Electrical Characteristics
VCC = 3.0 to 3.6V; RL = 50 to VCC-2V; TA = -40C to +85C, typical values at VCC = 3.3V, TA = 25C.
Symbol ICC LOSLVL VOH VOL VIHCMR VREF Parameter Power Supply Current LOSLVL Voltage PECL Output HIGH Voltage PECL Output LOW Voltage Common Mode Range Reference Voltage Condition No output load VREF Min Typ 26 Max 39 VCC Units mA V V V V V
VCC-1.085 VCC-0.955 VCC-0.880 VCC-1.850 VCC-1.705 VCC-1.555 GND+2.0 VCC VCC-1.48 VCC-1.32 VCC-1.16
TTL DC Electrical Characteristics
VCC = 3.0 to 3.6V; RL = 50 to VCC-2V; TA = -40C to +85C, typical values at VCC = 3.3V, TA = 25C. Symbol
VIH VIL IIH IIL VOH VOL
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.
Parameter
/EN Input HIGH Voltage /EN Input LOW Voltage /EN Input HIGH Current /EN Input LOW Current LOS Output HIGH Level LOS Output LOW Level
Condition
Min
2.0
Typ
Max
0.8
Units
V V A A mA V V
VIN = 2.7V VIN = VCC VIN = 0.5V VCC > 3.3V, IOH-MAX < 160A VCC < 3.3V, IOH-MAX < 160A IOL = +2mA -0.3 2.4 2.0
20 100
0.5
V
February 2007
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M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88903AL
AC Electrical Characteristics
VCC = 3.0 to 3.6V; RL = 50 to VCC-2V; TA = -40C to +85C, typical values at VCC = 3.3V, TA = 25C.
Symbol tr, tf tJITTER VID VOD tOFF tON LOSAL LOSDL HSYL LOSAM LOSDM HSYM LOSAH LOSDH HSYH B-3dB AV(Diff) S21
Notes: 3. Amplifier in limiting mode. Input is a 200MHz square wave. 4. Deterministic jitter measured using 1.25Gbps K28.5 pattern, VID = 10mVPP. 5. Random jitter measured using 1.25Gbps K28.7 pattern, VID = 10mVPP. 6. See "Typical Operating Characteristics" for a graph showing how to choose a particular RLOSLVL for a particular LOS assert and its associated de-assert amplitude. 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 upon the level of received optical power and ROSA characteristics. Based on that ratio, the optical hysteresis corresponding to the electrical hysteresis range 1dB-4.5 dB, shown in the AC characteristics table, will be 0.5dB-3dB Optical Hysteresis. 8. In real world applications, the LOS Release/Assert time can be strongly influenced by the RC time constant of the AC-coupling cap and the 50 input termination. To keep this time low, use a decoupling cap with the lowest value that is allowed by the data rate and the number of consecutive identical bits in the application (typical values are in the range of 0.001F to 1.0F).
Parameter Output Rise/Fall Time (20% to 80%) Deterministic Random Differential Input Voltage Swing Differential Output Voltage Swing LOS Release Time LOS Assert Time Low LOS Assert Level Low LOS De-assert Level Low LOS Hysteresis Medium LOS Assert Level Medium LOS De-assert Level Medium LOS Hysteresis High LOS Assert Level High LOS De-assert Level High LOS Hysteresis 3dB Bandwidth Differential Voltage Gain Single-Ended Small-Signal Gain
Condition Note 3 Note 4 Note 5 See Figure 1 VID > 18mVPP, See Figure 1 Note 8 Note 8 RLOSLVL = 15k, Note 6 RLOSLVL = 15k, Note 6 RLOSLVL = 15k, Note 7 RLOSLVL = 5k, Note 6 RLOSLVL = 5k, Note 6 RLOSLVL = 5k, Note 7 RLOSLVL = 100, Note 6 RLOSLVL = 100, Note 6 RLOSLVL = 100, Note 7
Min
Typ
Max 260
Units ps psPP psRMS
15 5 5 1500 40 125 2.3 3.4 3.4 2 2 8 2 4.2 6.2 3.4 10.8 16.4 3.4 1 42 30 36 21 5 9 5 500 500 1800
mVPP mVPP ns ns mVPP mVPP dB mVPP mVPP dB mVPP mVPP dB GHz dB dB
February 2007
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Micrel, Inc.
SY88903AL
Typical Operating Characteristics
VCC = 3.3V, TA = 25C, RL = 50 to VCC-2V, unless otherwise stated.
February 2007
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M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88903AL
Functional Block Diagram
Detailed Description
The SY88903AL high-sensitivity limiting post amplifier operates from a single +3.3V power supply, over temperatures from -40C to +85C. Signals with data rates from 622Mbps up to 1.25Gbps, and as small as 5mVpp, can be amplified. Figure 1 shows the allowed input voltage swing. The SY88903AL generates an LOS output, allowing feedback to /EN for output stability. LOSLVL 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 5mVpp to be detected and amplified. The input amplifier allows input signals as large as 1800mVpp. Input signals are linearly amplified with a typically 42dB differential voltage gain. Since it is a limiting amplifier, the SY88903AL outputs typically 1500mVpp voltage-limited waveforms for input signals that are greater than 12mVpp. Applications requiring the SY88903AL to operate with high-gain should have the upstream TIA placed as close as possible to the SY88903AL's input pins to ensure the best performance of the device. Output Buffer The SY88903AL's PECL output buffer is designed to drive 50 lines. The output buffer requires appropriate termination for proper operation. An external 50 resistor to VCC-2V for each output pin provides this. Figure 3 shows a simplified schematic of the output stage.
Loss-of-Signal The SY88903AL generates a chatter-free loss-of-signal (LOS) open-collector TTL output with internal 4.75k 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 set 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, 3.4dB LOS hysteresis is provided to prevent chattering. Loss-of-Signal-Level Set A programmable LOS level set pin (LOSLVL) sets the threshold of the input amplitude detection. Connecting an external resistor between VCC and LOSLVL sets the voltage at LOSLVL. This voltage ranges from VCC to VREF. The external resistor creates a voltage divider between VCC and VREF, as shown in Figure 5. Hysteresis The SY88903AL provides typically 3.4dB LOS electrical hysteresis. By definition, a power ratio measured in dB is 10log (power ratio). Power is calculated as V2IN/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 SY88903AL is an electrical device, this data sheet refers to hysteresis in electrical terms. With 3.4dB LOS hysteresis, a voltage factor of 1.5 is required to assert or de-assert LOS. 7
M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
February 2007
Micrel, Inc.
SY88903AL
Figure 1. VIS and VID Definition
Figure 2. Input Structure
Figure 3. Output Structure
Figure 4. LOS Output Structure
Figure 5. LOSLVL Setting Circuit Note: Recommended value for RLOSLVL is 15k or less.
Related Product and Support Documentation
Part Number Application Notes Function Notes on Sensitivity and Hysteresis in Micrel Post Amplifiers Data Sheet Link http://www.micrel.com/product-info/app_hints+notes.shtml
February 2007
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M9999-021707-D hbwhelp@micrel.com or (408) 955-1690
Micrel, Inc.
SY88903AL
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. (c) 2005 Micrel, Incorporated.
February 2007
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