3.3V/5V 622Mbps PECL LOW-POWER LIMITING POST AMPLIFIER WITH TTL SIGNAL DETECT Micrel, Inc. DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ SY88793V SY88793V Single 3.3V or 5V power supply Up to 622Mbps operation Low noise PECL data outputs Chatter-free TTL Signal Detect (SD) output TTL EN input Programmable SD level set (SDLVL) Available in a tiny 10-pin MSOP (3mm) package The SY88793V low-power limiting post amplifier is designed for use in fiber optic receivers. The device connects to typical transimpedance amplifiers (TIAs). The linear signal output from TIAs can contain significant amounts of noise and may vary in amplitude over time. The SY88793V quantizes these signals and outputs PECL level waveforms. The SY88793V operates from a single +3.3V or +5V power supply, over temperatures ranging from –40°C to +85°C. With its wide bandwidth and high gain, signals with data rates up to 622Mbps and as small as 5mVp-p can be amplified to drive devices with PECL inputs. The SY88793V generates a TTL SD output. A programmable signal-detect level set pin (SDLVL) sets the sensitivity of the input amplitude detection. SD asserts high if the input amplitude rises above the threshold set by SDLVL and deasserts low otherwise. EN deasserts the true output signal without removing the input signal. Typically 6dB SD hysteresis is provided to prevent chattering. APPLICATIONS ■ 622Mbps SONET/SDH ■ Small form factor transceivers ■ High-gain line driver and line receiver TYPICAL APPLICATIONS CIRCUIT VCC SD From Transimpedance Amp. 0.1µF DIN 0.1µF /DIN 50Ω 50Ω EN SY88793V SDLVL GND DOUT 0.1µF /DOUT 0.1µF VREF VCC 100kΩ 0.1µF Rpd To CDR Rpd GND For 3.3V, Rpd = 120Ω For 5V, Rpd = 220Ω M9999-072505 [email protected] or (408) 955-1690 Rev.: B 1 Amendment: /0 Issue Date: July 2005 SY88793V Micrel, Inc. PACKAGE/ORDERING INFORMATION EN 1 10 VCC Ordering Information DIN 2 9 DOUT /DIN 3 8 /DOUT Part Number Package Type Operating Range Package Marking Lead Finish 7 SD SY88793VKC K10-1 Commercial 793V Sn-Pb 6 GND SY88793VKCTR(1) K10-1 Commercial 793V Sn-Pb SY88793VKG K10-1 Industrial 793V with Pb-Free bar-line indicator Pb-Free NiPdAu SY88793VKGTR(1) K10-1 Industrial 793V with Pb-Free bar-line indicator Pb-Free NiPdAu VREF 4 SDLVL 5 10-Pin MSOP (K10-1) Note: 1. Tape and Reel. PIN DESCRIPTION Pin Number Pin Name Type 1 EN TTL Input: Default is high. 2 DIN Data Input True data input. 3 /DIN Data Input Complementary data input. 4 VREF 5 SDLVL Input 6 GND Ground 7 SD Open-collector TTL output w/ internal 6.75kΩ pullup resistor 8 /DOUT PECL Output Complementary data output. 9 DOUT PECL Output True data output. 10 VCC Power Supply Positive power supply. M9999-072505 [email protected] or (408) 955-1690 Pin Function Enable: Deasserts true data output when high. Reference voltage. Signal-Detect Level Set: A resistor from this pin to VCC sets the threshold for the data input amplitude at which SD will be asserted. Device ground. Signal-Detect: Asserts high when the data input amplitude rises above the threshold set by SDLVL. 2 SY88793V Micrel, Inc. Absolute Maximum Ratings(Note 1) Operating Ratings(Note 2) Supply Voltage (VCC) ....................................... 0V to +7.0V Input Voltage (DIN, /DIN) .........................................0 to VCC Output Current (IOUT) Continuous ............................................................. 50mA Surge .................................................................... 100mA EN Voltage ............................................................. 0 to VCC VREF Current ......................................... –800µA to +500µA SDLVL Voltage ................................................. VREF to VCC Lead Temperature (soldering, 20 sec.) ................... +260°C Storage Temperature (TS) ....................... –55°C to +125°C Supply Voltage (VCC) .............................. +3.0V to +3.6V or ............................................................ +4.5V to +5.5V Ambient Temperature (TA), Note 3 ............ –40°C to +85°C Junction Temperature (TJ), Note 3 .......... –40°C to +120°C Package Thermal Resistance MSOP (θJA) Still-Air .................................................. 113°C/W (ψJB) Still-Air .................................................... 74°C/W 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. Note 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. Note 3. Commercial devices are guaranteed from 0°C to +85°C ambient temperature. DC ELECTRICAL CHARACTERISTICS(Note 1) VCC = 3.0V to 3.6V or 4.5V to 5.5V; RLOAD = 50Ω to VCC–2V; TA = –40°C to +85°C; typical values at VCC = 3.3V, TA = 25°C. Symbol Parameter Condition Min ICC Power Supply Current no output load SDLVL SDLVL Voltage VIH EN Input HIGH Voltage VIL EN Input LOW Voltage IIH EN Input HIGH Current VIN = 2.7V VIN = VCC IIL EN Input LOW Current VIN = 0.5V –0.3 mA VOH SD Output HIGH Level VCC > 3.3V VCC < 3.3V 2.4 2.0 V V VOL SD Output LOW Level IOL = +2mA VOH PECL Output HIGH Voltage 50Ω to VCC–2V output load VCC–1.085 VCC–0.955 VCC–0.880 V VOL PECL Output LOW Voltage 50Ω to VCC–2V output load VCC–1.830 VCC–1.705 VCC–1.555 V VOFFSET Differential Output Offset VIHCMR Common Mode Range Note 2 GND +1.7 VREF Reference Voltage Note 3 VCC–1.38 Max Units 25 42 mA VCC V VREF 2.0 V 0.8 V 20 100 µA µA 0.5 Note 1. Specification for packaged product only. Note 2. The VIHCMR range is referenced to the most positive side of the differential input signal. Note 3. The current provided into or from VREF must be limited to 800µA source and 500µA sink. M9999-072505 [email protected] or (408) 955-1690 Typ 3 VCC–1.32 V ±100 mV VCC V VCC–1.26 V SY88793V Micrel, Inc. AC ELECTRICAL CHARACTERISTICS(Note 1) VCC = 3.0V to 3.6V or 4.5V to 5.5V; RLOAD = 50Ω to VCC–2V; TA = –40°C to +85°C; typical values at VCC = 3.3V, TA = 25°C. Symbol Parameter Condition Min Typ Max Units HYS SD Hysteresis electrical signal 2 4.6 8 dB tOFF SD Release Time 0.1 0.5 µs tON SD Assert Time 0.2 0.5 µs tr,tf Differential Output Rise/Fall Time (20% to 80%) 400 ps VID Differential Input Voltage Swing 1800 mVPP VOD Differential Output Voltage Swing VSR SD Sensitivity Range AV(Diff) Differential Voltage Gain B–3dB 3dB Bandwidth 700 S21 Single-Ended Small-Signal Gain 26 Note 1. 5 VID ≥ 18mVPP VID = 5mVPP 1500 400 mVPP mVPP 5 50 38 dB MHz 32 dB Specification for packaged product only. TYPICAL OPERATING CHARACTERISTICS SD Assert and Deassert Levels vs. SDLVL 120 80 SD Assert and Deassert Levels vs. RSDLVL VSUP = 3.3V TA = 25°C 622Mbps Pattern 223–1 120 100 VID (mVp-p) 100 VID (mVp-p) 140 VSUP = 3.3V TA = 25°C 622Mbps Pattern 223–1 60 ASSERT 40 80 ASSERT 60 40 0 1.2 1.4 SDLVL (referenced to VCC) (V) RSDLVL (Ω) M9999-072505 [email protected] or (408) 955-1690 4 100000 1 10000 0.2 0.4 0.6 0.8 1000 0 1 0 DEASSERT 100 20 DEASSERT 10 20 mVPP SY88793V Micrel, Inc. DETAILED DESCRIPTION SDLVL and deasserts low otherwise. SD can be fed back to the enable (EN) input to maintain output stability under a loss of signal condition. EN deasserts the true output signal without removing the input signals. Typically 6dB SD hysteresis is provided to prevent chattering. The SY88793V low-power limiting post amplifier operates from a single +3.3V or +5V power supply, over temperatures from –40°C to +85°C. Signals with data rates up to 622Mbps and as small as 5mVp-p can be amplified. Figure 1 shows the allowed input voltage swing. The SY88793V generates an SD output. SDLVL sets the sensitivity of the input amplitude detection. Signal-Detect Level Set A programmable SD level set pin (SDLVL) sets the threshold of the input amplitude detection. Connecting an external resistor between VCC and SDLVL sets the voltage at SDLVL. This voltages ranges from VCC to VREF. The external resistor creates a voltage divider between VCC and VREF as shown in Figure 5. If desired, an appropriate external voltage may be applied rather than using a resistor. The smaller the external resistor, implying a smaller voltage difference from SDLVL to VCC, the smaller the SD sensitivity. Hence, larger input amplitude is required to assert SD. “Typical Operating Characteristics” shows the relationship between the input amplitude detection sensitivity and the SDLVL voltage. Input Amplifier/Buffer Figure 2 shows a simplified schematic of the SY88793V's input stage. The high-sensitivity of the input amplifier allows signals as small as 5mVPP to be detected and amplified. The input amplifier allows input signals as large as 1800mVPP. Input signals are linearly amplified with a typically 38dB differential voltage gain. Since it is a limiting amplifier, the SY88793V outputs typically 1500mVPP voltage-limited waveforms for input signals that are greater than 18mVPP. Applications requiring the SY88793V to operate with highgain should have the upstream TIA placed as close as possible to the SY88793V’s input pins to ensure the best performance of the device. Hysteresis The SY88793V provides typically 6dB SD electrical hysteresis. By definition, a power ratio measured in dB is 10log(power ratio). Power is calculated as V2IN/R for an electrical signal. Hence the same ratio can be stated as 20log(voltage ratio). While in linear mode, the electrical voltage input changes linearly with the optical power and hence the ratios change linearly. Therefore, the optical hysteresis in dB is half the electrical hysteresis in dB given in the datasheet. The SY88793V provides typically 3dB SD optical hysteresis. As the SY88793V is an electrical device, this datasheet refers to hysteresis in electrical terms. With 6dB SD hysteresis, a voltage factor of two is required to assert or deassert SD. Output Buffer The SY88793V’s PECL output buffer is designed to drive 50Ω lines. The output buffer requires appropriate termination for proper operation. An external 50Ω resistor to VCC–2V for each output pin provides this. Figure 3 shows a simplified schematic of the output stage and includes an appropriate termination method. Signal-Detect The SY88793V generates a chatter-free SD open-collector TTL output with internal 6.75kΩ pullup resistor as shown in Figure 4. SD is used to determine that the input amplitude is large enough to be considered a valid input. SD asserts high if the input amplitude rises above the threshold set by M9999-072505 [email protected] or (408) 955-1690 5 SY88793V Micrel, Inc. DATA+ 2.5mV (Min.) VIS(mVp-p) 900mV (Max.) DATA— (DATA+) — (DATA—) 5mVp-p (Min.) VID(mVp-p) 1800mVp-p (Max.) Figure 1. VIS and VID Definitions VCC VCC ESD STRUCTURE DOUT /DOUT DIN /DIN ESD STRUCTURE GND GND Figure 2. Input Structure Figure 3. Output Structure VCC RSDLVL SDLVL VCC 6.75kΩ 3kΩ SD VREF Figure 4. SD Output Structure M9999-072505 [email protected] or (408) 955-1690 Figure 5. SDLVL Setting Circuit 6 SY88793V Micrel, Inc. FUNCTIONAL BLOCK DIAGRAM DIN Limiting Amplifer DOUT PECL Buffer /DIN /DOUT VREF Enable VCC GND EN Level Detect SD SDLVL DESIGN PROCEDURE Layout and PCB Design Since the SY88793V is a high-frequency component, performance can be largely determined by the board layout and design. A common problem with high-gain amplifiers is the feedback from the large swing outputs to the input via the power supply. M9999-072505 [email protected] or (408) 955-1690 The SY88793V’s 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. 7 SY88793V Micrel, Inc. 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 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. © 2005 Micrel, Incorporated. M9999-072505 [email protected] or (408) 955-1690 8