5V/3.3V 1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER FEATURES DESCRIPTION ■ ■ ■ ■ ■ ■ ■ ■ ■ 3.3V and 5V power supply option 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 (Micrel-Synergy laser diode driver and controller) ■ Available in a tiny 10-pin (3mm) MSOP The SY88903V 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 SY88903V generates a chatter-free Loss of Signal (LOS) open collector TTL output. The SY88903V 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. The sensitivity of the level detection can be adjusted using LOSLVL. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF as shown in Figure 3. Figure 4 and 5 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 9 DOUT SY88903V 8 /DOUT LOS /DIN 3 SY88903V FINAL MSOP K10-1 VREF 4 7 LOS LOSLVL 5 6 GND VCC 2k Figure 1. LOS Output with Desired Rise Time APPLICATIONS ■ ■ ■ ■ BLOCK DIAGRAM 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter DIN DOUT Limiting Amplifer ECL Buffer DIN DOUT VREF Enable VCC GND Level Detect LOS LOSLVL Rev.: A 1 EN Amendment: /1 Issue Date: July 2000 SY88903V FINAL Micrel PIN NAMES GENERAL DESCRIPTION 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 SY88903V 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 SY88903V 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 SY88903V FINAL Micrel DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% or +3.3V ±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 VOL TA = +85°C Min. Max. Min. Typ. Max. Min. Max. Unit — 30 40 — 42 mA — — –0.3(6) — mA 20(4) 20(4) µA 40 — 40 — –0.3(6) — –0.3(6) — –0.3(6) — — 20(4) 100(5) — — 20(4) 100(5) — — — — 100(5) — — 100(5) GND +2.0 VCC GND +2.0 VCC GND +2.0 — VCC GND +2.0 VCC V /EN Input HIGH Current VCMR TA = +25°C Max. Current(1) /EN Input LOW Current TA = 0°C Min. — ±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 µA 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 to +85°C TA = –40°C Symbol Parameter TA = 0°C TA = +25°C TA = +85°C Min. Max. Min. Max. Min. Typ. Max. Min. Max. Unit — dB Conditions PSRR Power Supply(1) Rejection Ratio — — — — — 35 — — VID Input Voltage Range 5 1800 5 1800 5 — 1800 5 1800 mVp-p tr, tf Output Rise/Fall Time — — 260 — — — 260 — — — — trin,tfin 260 — — — 260 — 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 223-1 pattern HYS LOS Hysteresis 2 8 2 8 2 4.6 8 2 8 dB 223-1 pattern NOTES: 1. Input referred noise = RMS output noise/low frequency gain. 2. Input is a 622MHz square wave. 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. 3 SY88903V FINAL Micrel DESIGN PROCEDURE Output Termination The SY88903V outputs must be terminated with a 50Ω load to VCC – 2V (or Thevenin equivalent). The SY88903V 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 SY88903V 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 R1 DIN+ 0.1µF 50 DIN– LOSLVL 50 R2 VREF VREF NOTES: R2 × 1.32V LOSLVS = VCC -1.32V + R1 + R2 R1 + R2 ≥ 2.6kΩ Figure 2. Differential Input Configuration Figure 3. LOSLVL Circut PRODUCT ORDERING CODE Ordering Code 4 Package Type Operating Range SY88903VKC K10-1 Commercial SY88903VKCTR K10-1 Commercial SY88903V FINAL Micrel PERFORMANCE CURVE LOS Assert and Deassert Levels vs LOSLVL 3.3V TA = 25°C 1.25Gbps Pattern 27-1 90 80 70 60 50 40 30 20 10 0 0 LOS Assert and Deassert Levels vs LOSLVL 100 90 INPUT LEVEL (mVp-p) INPUT LEVEL (mVp-p) 100 60 50 40 30 20 10 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL VCC – V 5.0V TA = 25°C 1.25Gbps Pattern 27-1 80 70 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL VCC – V Figure 5. 5.0V LOS Assert and Deassert Levels vs. LOSLVL Figure 4. 3.3V LOS Assert and Deassert Levels vs. LOSLVL 5 SY88903V FINAL Micrel 10 LEAD MSOP (K10-1) Rev. 00 MICREL-SYNERGY TEL + 1 (408) 980-9191 FAX 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 + 1 (408) 914-7878 WEB USA 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. © 1999 Micrel Incorporated 6