5V/3.3V 2.5Gbps HIGH-SPEED LIMITING POST AMPLIFIER DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ 3.3V and 5V power supply options 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 (Micrel-Synergy laser diode driver and controller) ■ Available in a tiny 10-pin (3mm) MSOP The SY88923V 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 SY88923V generates a chatter-free Loss of Signal (LOS) open collector TTL output. The SY88923V incorporates a programmable level detect function to identify when the input signal has been lost. The LOS output will change from logic “LOW” to logic “HIGH” when input signal is smaller than the swing set by LOSLVL. 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 show in Figure 3. Figure 4, 5, 6, and 7 show the relationship between input level sensitivity and the voltage set on LOSLVL. The LOS output is a TTL open collector output that requires a pull-up resistor for proper operation, Figure 1. PIN CONFIGURATION /EN 1 10 VCC DIN 2 /DIN 3 SY88923V 9 DOUT MSOP K10-1 VCC 8 /DOUT VREF 4 7 LOS LOSLVL 5 6 GND SY88923V 2k LOS Figure 1. LOS Output with Desired Rise Time BLOCK DIAGRAM APPLICATIONS ■ ■ ■ ■ ■ ■ 1.25Gbps and 2.5Gbps Gigabit Ethernet 531Mbps, 1062Mbps and 2.12Gbps Fibre Channel 622Mbps SONET Gigabit Interface Converter 2.5Gbps SDH/SONET 2.5Gbps Proprietary Links DIN DOUT Limiting Amplifer ECL Buffer /DIN /DOUT VREF Enable /EN VCC GND Level Detect LOS LOSLVL Rev.: B 1 Amendment: /0 Issue Date: August 2000 SY88923V Micrel PIN NAMES GENERAL DESCRIPTION Pin Type DIN Data Input Data Input /DIN Data Input Inverting Data Input LOSLVL 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 SY88923V is an integrated limiting amplifier intended for high-frequency fiber-optic applications. The circuit connects to typical trans-impedance 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 SY88923V limiting amplifier quantizes the signal and outputs a voltage-limited 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 to VCC +0.3 V /EN Input Voltage 0 to VCC V LOSLVL Input Voltage 0 to VCC V VREF Output Voltage VCC –2.0 to VCC 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. 2 SY88923V Micrel DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% or +3.3V ±10%, RLOAD = 50Ω to VCC –2V TA = –40°C Symbol Parameter ICC Power Supply Current(1) IIL /EN Input LOW Current /EN Input HIGH Current VCMR Common Mode Range Voffset Differential Output Offset LOSLVL LOSLVL Level VOL LOS Output Low TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit — — 40 40 — — 40 40 — — 30 28 40 40 — — 45 45 mA –0.3(6) — –0.3(6) — –0.3(6) — — –0.3(6) — mA — — 20(4) — — µA 100(5) — — 20(4) 100(5) — — 20(4) 100(5) — — 20(4) 100(5) GND +2.0 VCC GND +2.0 VCC GND +2.0 — VCC GND +2.0 VCC V — ±100 — ±100 — ±17 ±100 — ±100 mV VREF VCC VREF VCC VREF — VCC VREF VCC V — 0.5 — 0.5 — — 0.5 — 0.5 V — 100 — 100 — — 100 — 100 uA 5V 3.3V IIH TA = 0°C Level(2) Leakage(3) IOH LOS Output 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 –1555 VCC –1810 VCC –1620 VCC –1810 VCC –1705 VCC –1620 VCC –1810 VCC –1620 mV VREF Reference Supply VCC –1.38 VCC –1.26 VCC –1.38 VCC –1.26 VCC –1.38 VCC –1.32 VCC –1.26 VCC –1.38 VCC –1.26 V IREF VREF Output Current –0.8 0.5 –0.8 0.5 –0.8 — 0.5 –0.8 0.5 mA 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 NOTES: 1. No output load 2. IOL = + 2mA 3. VOH = 5.5V 4. VIN = 2.7V 5. VIN = VCC 6. VIN = 0.5V AC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% or +3.3V ±10%, RLOAD = 50Ω to VCC –2V TA = –40°C Symbol Parameter TA = 0°C TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit PSRR Power Supply(1) Rejection Ratio — — — — — 35 — — — dB VID Input Voltage Range 5 1800 5 1800 5 — 1800 5 VOD Differential Output Voltage Swing(2) — — — — — — — — — — 700 300 — — — — — — mV mV tOFFL LOS Release Time(3) Minimum 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 Conditions Input referred, 55MHz 1800 mVp-p VID = 15mVp-p VID = 5mVp-p tOFFH LOS Release Maximum Input — 0.5 — 0.5 — 0.1 0.5 — 0.5 µs VSR LOS Sensitivity Range 5 50 5 50 5 — 50 5 50 mVp-p 223-1 pattern HYS LOS Hysteresis 2 8 2 8 2 4.6 8 2 8 dB 223-1 pattern tr, tf Output Rise/Fall Time — — 175 — — — 175 — — — 150 trin,tfin 175 — — — 175 — ps VID > 100mVp-p VID < 100mVp-p Time(4) 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 a 622MHz square wave. 3 SY88923V Micrel DESIGN PROCEDURE Output Termination The SY88923V outputs must be terminated with a 50Ω load to VCC – 2V (or Thevenin equivalent). The SY88923V 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 SY88923V 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. VCC 0.1µF DIN+ R1 0.1µF 50Ω DIN– LOSLVL 50Ω R2 VREF VREF 0.1µF Figure 2. Differential Input Configuration Figure 3. LOSLVL Circuit NOTES: R2 × 1.32V LOSLVL = VCC -1.32V + R1 + R2 R1 + R2 ≥ 2.6kΩ PRODUCT ORDERING CODE Ordering Code 4 Package Type Operating Range SY88923VKC K10-1 Commercial SY88923VKCTR K10-1 Commercial SY88923V Micrel PERFORMANCE CURVE LOS Assert and Deassert Levels vs LOSLVL LOS Assert and Deassert Levels vs LOSLVL 100 3.3V TA = 25°C 2.5Gbps Pattern 223-1 90 80 70 60 INPUT LEVEL (mVp-p) INPUT LEVEL (mVp-p) 100 50 40 30 20 10 0 0 70 60 50 40 30 20 10 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL = VCC – V (V) 5.0V TA = 25°C 2.5Gbps Pattern 223-1 90 80 0 Figure 4. Figure 5. LOS Assert and Deassert Levels vs LOSLVL LOS Assert and Deassert Levels vs LOSLVL 100 3.3V TA = 25°C 2.5Gbps Pattern 27-1 90 80 70 60 50 INPUT LEVEL (mVp-p) INPUT LEVEL (mVp-p) 100 40 30 20 10 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL = VCC – V (V) 0 70 60 50 40 30 20 10 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL = VCC – V (V) Figure 6. 5.0V TA = 25°C 2.5Gbps Pattern 27-1 90 80 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL = VCC – V (V) Figure 7. 5 SY88923V Micrel 10 LEAD MSOP (K10-1) Rev. 00 6 SY88923V Micrel 7 SY88923V Micrel MICREL-SYNERGY TEL + 1 (408) 980-9191 FAX 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA + 1 (408) 914-7878 WEB http://www.synergysemi.com http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated 8