2.5Gbps HIGH-SPEED LIMITING POST AMPLIFIER Not recommended for new designs Micrel, Inc. DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ Up to 2.5Gbps 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 SY88922 and SY88904 or SY88905 ■ Available in a tiny 10-pin (3mm) MSOP The SY88923 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 2.5Gbps. Signals as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88923 generates a chatter-free Loss of Signal (LOS) open collector TTL output. The SY88923 incorporates a programmable 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 condition. Using LOSLVL pin, the sensitivity of the level detection can be adjusted. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF. Figure 3 and Figure 4 show 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 a pull-up resistor for proper operation, Figure 1. APPLICATIONS ■ ■ ■ ■ ■ SY88923 SY88923 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit interface converter 2.5Gbps SDH/SONET +5.0V SY88923 LOS 2.5k Figure 1. LOS Output with Desired Rise Time BLOCK DIAGRAM DIN DOUT Limiting Amplifer ECL Buffer DIN DOUT VREF Enable VCC Level Detect GND LOS LOSLVL M9999-061907 [email protected] or (408) 955-1690 EN Rev.: F 1 Amendment: /0 Issue Date: June 2007 Micrel, Inc. SY88923 PACKAGE/ORDERING INFORMATION Ordering Information /EN 1 10 VCC 9 DOUT Part Number Package Type Operating Range Package Marking Lead Finish 8 /DOUT SY88923KC K10-1 Commercial 923 Sn-Pb VREF 4 7 LOS SY88923KCTR(1) K10-1 Commercial 923 Sn-Pb LOSLVL 5 6 GND SY88923KG K10-1 Industrial 923 with Pb-Free bar-line indicator Pb-Free NiPdAu SY88923KGTR(1) K10-1 Industrial 923 with Pb-Free bar-line indicator Pb-Free NiPdAu DIN 2 /DIN 3 MSOP K10-1 10-Pin MSOP (K10-1) Note: 1. Tape and Reel. GENERAL DESCRIPTION PIN NAMES Pin Type DIN Data Input Data Input /DIN Data Input Inverting Data Input LOS LVL Input LOS Limit 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 Inverting Data Output DOUT PECL Output Data Output VCC Power Supply Positive Power Supply VREF Output Reference Voltage Output for LOS Level Set (see Fig. 3) General The SY88923 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 SY88923 limiting amplifier quantizes the signal and outputs a voltagelimited waveform. The /EN pin allows the user to disable the output signal without removing the input signal. Function 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. SY88923 DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10%, RLOAD = 50Ω to VCC-2V, TA = –40°C to +85°C TA = –40°C Symbol ICC IIL IIH Parameter Power Supply Common Mode Range Voffset Differential Output Offset LOSLVL LOSLVL Level(2) VOL LOS Output Low TA = +85°C Max. Min. Max. Min. Typ. Max. Min. Max. Unit — 21 35 — 35 mA — — –0.3(8) — mA — — 20(5) — — 20(5) µA 35 — 35 — –0.3(8) — –0.3(8) — –0.3(8) — — 20(5) — — 20(5) /EN Input HIGH Current VCMR TA = +25°C Min. Current(1) /EN Input LOW Current TA = 0°C 100(6) — — 100(6) GND +2.0 VCC –1.0 GND +2.0 VCC –1.0 GND +2.0 — 100(6) 100(6) VCC –1.0 GND +2.0 VCC –1.0 V — ±100 — ±100 — — ±100 — ±100 mV VREF VCC VREF VCC VREF — VCC VREF VCC V — 0.5 — 0.5 — — 0.5 — 0.5 V — 250 — 250 — — 250 — 250 uA Level(3) Leakage(4) IOH LOS Output VOH DOUT and /DOUT HIGH Output VCC–1085 VCC–880 mV VOL DOUT and /DOUT LOW Output VCC–1830 VCC–1555 VCC–1810 VCC–1620 VCC–1810 VCC–1705 VCC–1620 VCC–1810 VCC–1620 mV VREF Reference Supply(7) 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 V 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–880 VCC–1025 VCC–880 VCC–1025 VCC–955 VCC–880 VCC–1025 5. 6. 7. 8. Notes: 1. No output load. 2. 223-1 pattern. 3. IOL = + 2mA. 4. VOH = 5.5V. VIN = 2.7. VIN =VCC. IREF must be limited within –0.8mA (source) and 0.4mA (sink). VIN = 0.5V. 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 mVp-p tr, tf Output Rise/Fall Time — — 175 — — — 175 — — — — trin,tfin 175 — — — 175 — ps VID > 100mVp-p VID < 100mVp-p VOD Differential Output Voltage Swing(2) — — — — — — — — — — 600 200 — — — — — — mV mV VID = 15mVp-p VID = 5mVp-p 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 mVp-p HYS LOS Hysteresis 2 8 2 8 2 4.6 8 2 8 dB Notes: 1. Input referred noise = RMS output noise/low frequency gain. 2. Input is a 622MHz square wave. M9999-061907 [email protected] or (408) 955-1690 Conditions Input referred, 55MHz 223-1 pattern 3. Input is a 200MHz square wave, tr < 300ps, 8mVp-p. 4. Input is a 200MHz square wave, tr < 300ps, 1.8Vp-p. 3 Micrel, Inc. SY88923 DESIGN PROCEDURE PERFORMANCE CURVE Output Termination The SY88923 outputs must be terminated with a 50Ω load to VCC – 2V (or thevenin equivalent). LOS Assert and Deassert Levels vs LOSLVL 100.00 90.00 Layout and PCB Design Since the SY88923 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 power supply. The SY88923 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. Deassert 80.00 Level (mV) 70.00 60.00 Assert 50.00 40.00 30.00 20.00 5.00 4.75 4.88 4.51 4.63 4.26 4.38 4.01 4.13 3.89 3.64 3.76 3.39 3.52 3.14 3.27 2.77 2.90 3.02 2.53 0.00 2.65 10.00 LOSLVL (V) 0.1µF 0.1µF 50Ω DIN+ Figure 4. 223-1 Pattern DIN– 50Ω VREF 0.1µF LOS Assert and Deassert Levels vs Resistor Divide 100.00 90.00 Figure 2. Differential Input Configuration 80.00 Deassert Level (mV) 70.00 VCC 60.00 Assert 50.00 40.00 30.00 20.00 R1 10.00 Figure 5. 223-1 Pattern VREF Note: Resistor Divider = R2/ (R1 + R2) R1 + R2 ≥ 5kΩ Figure 3. LOSLVL Circut M9999-061907 [email protected] or (408) 955-1690 4 1.00 0.90 0.95 0.80 Resistor Divider R2 / (R1 + R2) 0.85 0.70 0.75 0.65 0.55 0.60 0.45 0.50 0.35 0.40 0.30 0.20 0.25 0.10 0.00 0.05 R2 0.15 0.00 LOSLVL SY88923 Micrel, Inc. APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION GBIC Terminal TX_DATA+ TX_DATA– VCC DIN DIN LOSOUT EN VREF RSET 20kΩ VREF GND SY88922 VCC IBIAS GND SY88905 VCC LOS VCC OUT RSER VCC 0.1µF 20kΩ 20kΩ OUT MD IBIAS SET IBIAS FB IPIN SET DIN DIN 24Ω LOSLVL BLM21A102S VCC Laser Module The value of RSER depends on the Laser Diode. VCC 82Ω LOSIN EN SY88923 VREF 130Ω Laserdiode REXT 1000pF 82Ω 68Ω 68Ω Photodiode 130Ω 200Ω 200Ω ENABLE/DISABLE VCC DOUT DOUT GND 0.1µF 68Ω 68Ω 5 M9999-061907 [email protected] or (408) 955-1690 RX_LOS RX_DATA+ RX_DATA– VCC 20kΩ 200Ω 200Ω Micrel, Inc. SY88923 10-PIN 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 datasheet 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. © 2006 Micrel, Incorporated. M9999-061907 [email protected] or (408) 955-1690 6