SY88147DL 3.3V, 1.25Gbps PECL Limiting Post Amplifier w/High Gain TTL Loss-of-Signal General Description Features 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 –40oC to +85oC. With its wide bandwidth and high gain, signals with data rates up to 1.25Gbps, and as small as 5mVPP, 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 (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 3.5dB LOS hysteresis is provided to prevent chattering. All support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • February 2007 1 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 (LOSLVL) • 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 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL Typical Application Circuit February 2007 2 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL Ordering Information Lead Finish Package Type Operating Range Package Marking 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 Part Number Note: 1. Tape and Reel. Pin Configuration 10-Pin MSOP (K10-1) Pin Description Pin Number Pin Name Type 1 /EN TTL Input: Default is HIGH. 2 DIN Data Input True data input. 3 /DIN Data Input Complementary data input. 4 VREF 5 LOSLVL Input 6 GND, Exposed Pad Ground 7 LOS Open-collector TTL output w/internal 4.75kΩ pull-up resistor 8 /DOUT PECL Output Complementary data output. 9 DOUT PECL Output True data output. 10 VCC Power Supply Positive power supply. February 2007 Pin Function /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. Reference voltage: Placing a capacitor here to VCC helps stabilize LOSLVL. 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 sets by LOSLVL. 3 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC) ....................................... 0V to +4.0V Input Voltage (DIN, /DIN) .......................................0 to VCC Output Current (IOUT) Continuous........................................................ ±50mA Surge .............................................................. ±100mA /EN Voltage ............................................................0 to VCC VREF Current .......................................... -800µA to +500µA LOSLVL Voltage................................................. VREF to VCC Lead Temperature (soldering, 20sec.) ................... +260°C Storage Temperature (Ts) ....................... –65°C to +150°C Supply Voltage (VCC)............................. +3.0V to +3.6V Ambient Temperature (TA) ................... –40°C to +85°C Junction Temperature (TJ) ................. –40°C to +125°C Junction Thermal Resistance MSOP (θJA) Still-air .......................................... 113°C/W DC Electrical Characteristics VCC = 3.0 to 3.6V; RL = 50Ω to VCC–2V; TA = –40°C to +85°C, typical values at VCC = 3.3V, TA = 25°C. Symbol Parameter Condition Min Typ ICC Power Supply Current No output load LOSLVL LOSLVL Voltage VOH PECL Output HIGH Voltage VCC-1.085 VCC-0.955 VCC-0.880 VOL PECL Output LOW Voltage VCC-1.850 VCC-1.705 VCC-1.555 V VIHCMR Common Mode Range GND+2.0 V VREF Reference Voltage VCC-1.48 VCC-1.32 VCC-1.16 26 VREF Max Units 39 mA VCC V VCC V V TTL DC Electrical Characteristics VCC = 3.0 to 3.6V; RL = 50Ω to VCC–2V; TA = –40°C to +85°C, typical values at VCC = 3.3V, TA = 25°C. Symbol Parameter Condition Min Typ Max Units VIH /EN Input HIGH Voltage VIL /EN Input LOW Voltage 0.8 V IIH /EN Input HIGH Current 20 µA IIL /EN Input LOW Current VIN = 0.5V -0.3 mA VOH LOS Output HIGH Level VCC > 3.3V, IOH-MAX < 160µA 2.4 V VCC < 3.3V, IOH-MAX < 160µA 2.0 VOL LOS Output LOW Level 2.0 VIN = 2.7V VIN = VCC V 100 IOL = +2mA µA V 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. February 2007 4 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL AC Electrical Characteristics VCC = 3.0V to 3.6V; RLOAD =50 to VCC–2V; TA = –40°C to +85°C. Symbol Parameter Condition tr, tf Output Rise/Fall Time (20% to 80%) Note 4 tJITTER Min Typ Max 260 Units ps Deterministic Note 5 15 psPP Random Note 6 5 psRMS VID Differential Input Voltage Swing Figure 1 VOD Differential Output Voltage Swing VID > 18mVPP Figure 1 TOFF LOS Release Time 2 10 µs TON LOS Assert Time 2 10 µs 5 1800 mvPP mvPP 1500 LOSAL Low LOS Assert Level RLOSLVL = 15kΩ, Note 8 2.3 mVPP LOSDL Low LOS De-assert Level RLOSLVL = 15kΩ, Note 8 3.4 mVPP HYSL Low LOS Hysteresis RLOSLVL = 15kΩ, Note 7 3.4 dB LOSAM Medium LOS Assert Level RLOSLVL = 5kΩ, Note 8 4.2 mVPP LOSDM Medium LOS De-assert Level RLOSLVL = 5kΩ, Note 8 6.2 mVPP HYSM Medium LOS Hysteresis RLOSLVL = 5kΩ, Note 7 LOSAH High LOS Assert Level RLOSLVL = 100Ω, Note 8 10.8 mVPP LOSDH High LOS De-assert Level RLOSLVL = 100Ω, Note 8 16.4 mVPP HYSH High LOS Hysteresis RLOSLVL = 100Ω, Note 7 B-3dB 3dB Bandwidth AV(Diff) Differential Voltage Gain S21 Single-ended Small-Signal Gain 2 2 30 3.4 3.6 4.5 4.5 dB dB 1 GHz 42 dB 36 dB Notes: 4. Amplifier in limiting mode. Input is a 200MHz square wave. 5. Deterministic jitter measured using 1.25Gbps K28.5 pattern, VID = 10mVPP. 6. Random jitter measured using 1.25Gbps K28.7 pattern, VID = 10mVPP. 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 RLOSLVL for a particular LOS assert and its associated de-assert amplitude. February 2007 5 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL Typical Operating Characteristics VCC = 3.3V, TA = 25°C, RL = 50Ω to VCC–2V, unless otherwise stated. February 2007 6 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL 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 5mVPP can be amplified. Figure 1 shows the allowed input voltage swing. The SY88147DL generates a 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 SY88147DL outputs typically 1500mVPP voltage-limited waveforms for input signals that are greater than 12mVpp. 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. 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 (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. 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 VCC–2V for each output pin provides this. Figure 3 shows a simplified schematic of the output stage. 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 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 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. February 2007 7 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL 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 15kΩ or less. February 2007 8 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL Related Product and 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 February 2007 9 M9999-021207-B [email protected] or (408) 955-1690 Micrel, Inc. SY88147DL 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. February 2007 10 M9999-021207-B [email protected] or (408) 955-1690