5V/3.3V 1.25Gbps HIGH-SPEED LIMITING POST AMPLIFIER Micrel, Inc. 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 laser diode driver and controller ■ Available in a tiny 10-pin (3mm × 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 5mVpp 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 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. 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. “Typical Characteristics” 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. APPLICATIONS ■ ■ ■ ■ 1.25Gbps Gigabit Ethernet 531Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter VCC BLOCK DIAGRAM SY88903V LOS DIN 2k DOUT Limiting Amplifer ECL Buffer Figure 1. LOS Output with Desired Rise Time DIN DOUT All support documentation can be found on Micrel’s web site at www.micrel.com. VREF Enable VCC GND SY88903V SY88903V EN Level Detect LOSLVL M9999-041505 [email protected] or (408) 955-1690 LOS Rev.: B 1 Amendment: /0 Issue Date: April 2005 Micrel, Inc. SY88903V PACKAGE/ORDERING INFORMATION Ordering Information(1) /EN 1 10 VCC DIN 2 9 DOUT /DIN 3 8 /DOUT VREF 4 7 LOS LOSLVL 5 6 GND 10-Pin MSOP (K10-1) Part Number Package Type Operating Range Package Marking Lead Finish SY88903VKC K10-1 Commercial 903V with Pb-free bar-line indicator Sn-Pb SY88903VKCTR(2) K10-1 Commercial 903V with Pb-free bar-line indicator Sn-Pb SY88903VKG K10-1 Industrial 903V with Pb-free bar-line indicator NiPdAu SY88903VKGTR(2) K10-1 Industrial 903V with Pb-free bar-line indicator NiPdAu Notes: 1. Contact factory for die availability. Die is guaranteed at TA = 25°C, DC electricals only. 2. Tape and Reel. PIN DESCRIPTION Pin Number Pin Name Type 1 EN TTL Input Output Enable (Active Low). 2 DIN Data Input Data Input. 3 /DIN Data Input Inverting Data Input. 4 VREF Output 5 LOSLVL Input 6 GND Ground 7 LOS TTL Output (Open Collector) 8 /DOUT PECL Output Inverting Data Output. 9 DOUT PECL Output Data Output. 10 VCC Power Supply Positive Power Supply. M9999-041505 [email protected] or (408) 955-1690 Pin Function Reference Voltage Output for LOS Level Set (see Figure 3). LOS Limit Set. Ground Loss-of-Signal Indicator (Active Low). 2 Micrel, Inc. SY88903V Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC) ....................................... 0V to +7.0V Input Voltage (DIN, /DIN, /EN, LOSLVL) ............... 0V to VCC Output Voltage (DOUT, /DOUT) with 50Ω Load ... VCC –2.5V to VCC +0.3V (VREF) ............................................ VCC –2.0V to VCC Lead Temperature (soldering, 10 sec.) ..................... 270°C Storage Temperature (TS) ....................... –55°C to +125°C Supply Voltage (VIN) ...................................... +xxV to +xxV Ambient Temperature (TA) ......................... –40°C to +85°C Package Thermal Resistance MSOP (θJA) ......................................................... xx°C/W DC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% or +3.3V ±10%; RLOAD = 50Ω to VCC –2V; TA = –40°C to +85°C; unless noted. Symbol Parameter Condition Min Typ Max Units ICC Power Supply Current No output load 30 42 mA IIL /EN Input LOW Current VIN = 0.5V IIH /EN Input HIGH Current VIN = 2.7V VIN = VCC VCMR Common Mode Range Voffset Differential Output Offset LOSLVL LOSLVL Level VOL LOS Output Low Level IOH LOS Output Leakage VOH DOUT and /DOUT HIGH Output VCC –1085 VCC –955 VOL –0.3 mA 20 100 µA VCC V ±100 mV VCC V IOL = +2mA 0.5 V VOH = 5.5V 250 µA VCC –880 mV DOUT and /DOUT LOW Output VCC –1830 VCC –1705 VCC –1620 mV VREF Reference Supply VCC –1.38 VCC –1.32 VCC –1.26 V IREF VREF Output Current –0.8 VIH /EN Input HIGH Voltage 2.0 VIL /EN Input LOW Voltage GND +2.0 VREF 0.5 mA V 0.8 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 Ratings” 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. M9999-041505 [email protected] or (408) 955-1690 3 Micrel, Inc. SY88903V AC ELECTRICAL CHARACTERISTICS VCC = +5V ±10% or +3.3V ±10%; RLOAD = 50Ω to VCC –2V; TA = –40°C to +85°C; unless noted. Symbol Parameter Condition Min PSRR Power Supply(3) Rejection Ratio Input referred, 55MHz VID Input Voltage Range tr, tf Output Rise/Fall Time Typ Max 35 5 VID > 100mVpp VID < 100mVpp trin,tfin VID = 15mVpp VID = 5mVpp 600 200 Units dB 1800 mVpp 260 ps VOD Differential Output Voltage Swing(4) tOFFL LOS Release Time(5) Minimum Input 0.1 0.5 µs tOFFH LOS Release Time(6) Maximum Input 0.1 0.5 µs tONL LOS Assert Time(5) 0.2 0.5 µs VSR LOS Sensitivity Range 223–1 pattern 5 50 mVpp LOS Hysteresis 223–1 2 8 dB HYS pattern 4.6 Notes: 3. Input referred noise = RMS output noise/low frequency gain. 4. Input is a 622MHz square wave. 5. Input is a 200MHz square wave, tr < 300ps, 8mVpp. 6. Input is a 200MHz square wave, tr < 300ps, 1.8Vpp. TYPICAL CHARACTERISTICS LOS Assert and De-assert Levels vs LOSLVL 100 90 3.3V TA = 25°C 1.25Gbps Pattern 27-1 80 70 60 INPUT LEVEL (mVpp) INPUT LEVEL (mVpp) 100 90 50 40 30 20 10 0 0 4 5.0V TA = 25°C 1.25Gbps Pattern 27-1 80 70 60 50 40 30 20 10 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL VCC – V M9999-041505 [email protected] or (408) 955-1690 LOS Assert and De-assert Levels vs LOSLVL 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL VCC – V mV mV Micrel, Inc. SY88903V 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 R1 LOSLVL 0.1µF 0.1µF 50Ω R2 DIN+ VREF DIN– 50Ω Notes: R2 × 1.32V LOSLVS = VCC -1.32V + R1 + R2 VREF R1 + R2 ≥ 2.6kΩ 0.1µF Figure 3. LOSLVL Circut Figure 2. Differential Input Configuration M9999-041505 [email protected] or (408) 955-1690 5 Micrel, Inc. SY88903V 10 LEAD MSOP (K10-1) Rev. 00 MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB USA 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. M9999-041505 [email protected] or (408) 955-1690 6