1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER Not recommended for new designs Micrel, Inc. DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ Up to 1.25Gbps operation Low noise Chatter-Free LOS Generation Open Collector TTL LOS Output TTL /EN Input Differential PECL inputs for data Single power supply Designed for use with SY88902 and SY88904 Available in a tiny 10-pin (3mm) MSOP The SY88903 limiting post amplifier with its high gain and wide bandwidth is ideal for use as a post amplifier in fiber-optic receivers with data rates up to 1.25Gbps. Signals as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88903 generates a chatter-free Loss of Signal (LOS) open collector TTL output. The SY88903 incorporates a programmble level detect function to identify when the input signal has been lost. This information can be fed back to the /EN input of the device to maintain stability under loss of signal conditions. Using LOSLVL pin the sensitivity of the level detect can be adjusted. The LOS LVL voltage can be set by connecting a resistor divider between VCC and VREF, Figure 3. Figure 4 shows the relationship between input level sensitivity and the voltage set on LOSLVL. Figure 5 shows the relationship between input level sensitivity and resistor divider ratio. The LOS output is a TTL open collector output that requires pull-up resistor for proper operation, Figure 1. APPLICATIONS ■ ■ ■ ■ SY88903 SY88903 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter +5V 2k SY88903 LOS Figure 1. LOS Output with Desired Rise Time BLOCK DIAGRAM DIN Limiting Amplifier DOUT ECL Buffer DOUT DIN VREF Enable VCC GND Level Detect LOS LOSLVL M9999-061907 [email protected] or (408) 955-1690 EN 1 Rev.: I Amendment: /0 Issue Date: June 2007 Micrel, Inc. SY88903 PACKAGE/ORDERING INFORMATION Ordering Information /EN 1 10 VCC DIN 2 9 DOUT Part Number MSOP K10-1 Package Type Operating Range Package Marking Lead Finish 8 /DOUT SY88903KC K10-1 Commercial 903 Sn-Pb VREF 4 7 LOS SY88903KCTR(1) K10-1 Commercial 903 Sn-Pb LOSLVL 5 6 GND SY88903KH K10-1 Commercial 903 with Pb-Free bar-line indicator Pb-Free NiPdAu SY88903KHTR(1) K10-1 Commercial 903 with Pb-Free bar-line indicator Pb-Free NiPdAu /DIN 3 10-Pin MSOP (K10-1) Note: 1. Tape and Reel. PIN NAMES Pin GENERAL DESCRIPTION Type DIN Data Input /DIN Data Input LOS LVL Input General The SY88903 is an integrated limiting amplifier intended for high-frequency fiber-optic applications. The circuit connects to typical transimpedance amplifiers found within a fiber-optics link. The linear signal output from a transimpedance amplifier can contain significant amounts of noise, and may vary in amplitude over time. The SY88903 limiting amplifier quantizes the signal and outputs a voltagelimited waveform. The TTL /EN pin allows the user to disable the output signal without removing the input signal. Function Data Input Inverting Data Input Loss of Signal Level Set /EN TTL Input Output Enable (active Low) LOS TTL Output (Open Collector) Loss of Signal Indicator (active High) GND Ground Ground DOUT PECL Output Data Output /DOUT PECL Output Inverting Data Output VCC Power Supply Positive Power Supply VREF Output Reference Voltage Output for LOS Level Set (see Fig. 3) ABSOLUTE MAXIMUM RATINGS(1) Symbol Rating Value Unit VCC Power Supply Voltage 0 to +7.0 V DIN, /DIN Input Voltage 0 to VCC V DOUT, /DOUT Output Voltage (with 50Ω load) VCC –2.5, VCC +0.3 V TA Operating Temperature Range –40 to +85 °C Tstore Storage Temperature Range –55 to +125 °C Note: 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 ratlng conditions for extended periods may affect device reliability. M9999-061907 [email protected] or (408) 955-1690 2 Micrel, Inc. SY88903 DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10%, RLOAD = 50Ω to VCC-2V, TA = –40°C to +85°C TA = –40°C Symbol Parameter Power Supply IIL /EN Input LOW Current TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit — 35 — 35 — 21 35 — 35 mA –0.3 — –0.3 — –0.3 — — –0.3 — mA 20(5) 100(6) — — 20(5) 100(6) — — 20(5) 100(6) — — 20(5) 100(6) µA Current(1) ICC TA = 0°C IIH /EN Input HIGH Current — — VCMR Common Mode Range GND +2.0 Voffset Differential Output Offset LOSLVL LOSLVL Level VOL — — VCC -1.0 GND +2.0 VCC -1.0 GND +2.0 — VCC -1.0 GND +2.0 VCC -1.0 V — ±100 — ±100 — — ±100 — ±100 mV VREF VCC VREF VCC VREF — VCC VREF VCC V LOS Output Low Level(2) — 0.5 — 0.5 — — 0.5 — 0.5 V IOH LOS Output Leakage(3) — 250 — 250 — — 250 — 250 uA VOH DOUT and /DOUT HIGH Output VCC-1085 VCC-880 VCC-1025 VCC-880 VCC-1025 VCC-955 VCC-880 VCC-1025 VCC-880 mV VOL DOUT and /DOUT LOW Output VCC-1830 VCC-1810 VCC–1620 mV VREF Reference Supply(4) VCC-2.625 VCC–2.325 VCC-2.625 VCC–2.325 VCC-2.625 VCC–2.475 VCC–2.325 VCC-2.625 VCC–2.325 VIH /EN Input HIGH Voltage 2.0 — 2.0 — 2.0 — — 2.0 — V VIL /EN Input LOW Voltage — 0.8 — 0.8 — — 0.8 — 0.8 V VCC–1555 VCC-1810 VCC–1620 VCC-1810 VCC–1705 VCC–1620 Notes: 1. No output load 2. IOL = + 2mA 3. VOH = 5.5V V 4. IREF must be limited to be within -0.8mA (source) and 0.5mA (sink). 5. VIN = 2.7V 6. VIN = VCC AC ELECTRICAL CHARACTERISTICS VCC = +5V ±10%, RLOAD = 50Ω to VCC - 2V, TA = –40°C to +85°C TA = –40°C Symbol Parameter PSRR Supply(1) TA = 0°C TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit Power Rejection Ratio — — — — — 35 — — — dB VID Input Voltage Range 5 1800 5 1800 5 — 1800 5 1800 mVPP tr, tf Output Rise/Fall Time — — 350 — — — 350 — — — 200 trin,tfin 350 — — — 350 — ps VID > 100mVPP VID < 100mVPP VOD Differential Output Voltage Swing(2) — — — — — — — — — — 600 200 — — — — — — mV mV VID = 15mVPP VID = 5mVPP tOFFL LOS Release Time(3) Minimum Input — 0.5 — 0.5 — 0.1 0.5 — 0.5 µs tOFFH LOS Release Time(4) Maximum Input — 0.5 — 0.5 — 0.1 0.5 — 0.5 µs tONL LOS Assert Time(3) — 0.5 — 0.5 — 0.2 0.5 — 0.5 µs VSR LOS Sensitivity Range 5 50 5 50 5 — 50 5 50 mVPP HYS LOS Hysteresis 2 8 2 8 2 4.6 8 2 8 dB Input referred, 55MHz 3. Input is a 200MHz square wave, tr < 300ps, 8mVp-p. 4. Input is a 200MHz square wave, tr < 300ps, 1.8Vp-p. Notes: 1. Input referred noise = RMS output noise/low frequency gain. 2. Input is 622MHz square wave. M9999-061907 [email protected] or (408) 955-1690 Conditions 3 Micrel, Inc. SY88903 APPLICATION INFORMATION Output Termination The SY88903 outputs must be terminated with a 50Ω load to VCC – 2V (or Thevenin equivalent). The SY88903 ground pin should be connected to the circuit board ground. Use multiple PCB vias close to the part to connect to ground. Avoid long, inductive runs which can degrade performance. Layout and PCB Design Since the SY88903 is a high-frequency component, performance can largely be determined by board layout and design. A common problem with high-gain amplifiers is feedback from the large swing outputs to the input via the power supply. NOTES: Resistor Divider = R2/ (R1 + R2) R1 + R2 ≥ 5kΩ VCC R1 0.1µF DIN– LOSLVL R2 50Ω DIN+ 50Ω 0.1µF VREF VREF 0.1µF Figure 3. LOSLVL Circut Figure 2. Differential Input Configuration M9999-061907 [email protected] or (408) 955-1690 4 Micrel, Inc. SY88903 PERFORMANCE CURVE 100.00 90.00 Deassert 80.00 70.00 Level (mV) 60.00 Assert 50.00 40.00 30.00 20.00 10.00 5.00 4.75 4.88 4.63 4.38 4.51 4.13 4.26 4.01 3.76 3.89 3.52 3.64 3.39 3.14 3.27 2.90 3.02 2.77 2.53 2.65 0.00 LOSlvl (V) Figure 4. LOS Assert and Deassert Levels vs LOSLVL 100.00 90.00 80.00 Deassert 70.00 Level (mV) 60.00 Assert 50.00 40.00 30.00 20.00 10.00 1.00 0.95 0.90 0.85 0.75 0.80 0.70 0.65 0.60 0.50 0.55 0.45 0.40 0.35 0.25 0.30 0.20 0.15 0.10 0.00 0.05 0.00 Resistor Divider R2 / (R1 + R2) Figure 5. LOS Assert and Deassert Levels vs Resistor Divider M9999-061907 [email protected] or (408) 955-1690 5 SY88903 Micrel, Inc. APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION GBIC Terminal TX_DATA+ VCC DIN DIN LOSOUT EN VREF RSET 20kΩ VREF GND SY88902 VCC IBIAS SY88905 GND VCC OUT RSER VCC 20kΩ 20kΩ OUT MD IBIAS SET IBIAS FB IPIN SET DIN DIN 0.1µF BLM21A102S VCC Laser Module The value of RSER depends on the Laser Diode. VCC 6 M9999-061907 [email protected] or (408) 955-1690 24Ω LOSLVL 82Ω LOSIN VCC LOS SY88903 VREF 130Ω Laserdiode REXT 1000pF 82Ω 82Ω 82Ω Photodiode 130Ω 130Ω 130Ω TX_DATA– VCC EN DOUT DOUT GND 0.1µF 82Ω 82Ω ENABLE/DISABLE RX_LOS RX_DATA+ RX_DATA– VCC 20kΩ 130Ω 130Ω Micrel, Inc. SY88903 10 LEAD MSOP (K10-1) Rev. 00 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 at Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2005 Micrel, Incorporated. M9999-061907 [email protected] or (408) 955-1690 7