SY88703V DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ SY88703V 3.3V/5V 622Mbps PECL LOW-POWER LIMITING POST AMPLIFIER W/TTL LOS Micrel, Inc. Single 3.3V or 5V power supply Up to 622Mbps operation Low noise PECL data outputs Chatter-free TTL Loss-of-Signal (LOS) output TTL /EN input Programmable LOS level set (LOSLVL) Available in a tiny 10-pin MSOP (3mm) package The SY88703V 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 SY88703V quantizes these signals and outputs PECL level waveforms. The SY88703V 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 SY88703V generates a TTL LOS output. A programmable loss-of-signal level set pin (LOSLVL) sets the sensitivity of the input amplitude detection. LOS asserts high if the input amplitude falls below the threshold set by LOSLVL and deasserts low otherwise. /EN deasserts the true output signal without removing the input signal. Typically 4.6dB loss-of-signal 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 2kΩ VCC LOS From Transimpedance Amp. 0.1µF DIN 0.1µF /DIN 50Ω 50Ω /EN SY88703V LOSLVL VREF DOUT 0.1µF /DOUT 0.1µF Rpd To CDR Rpd VCC GND GND 100Ω M9999-052406 [email protected] or (408) 955-1690 3kΩ For 3.3V, Rpd = 120Ω For 5V, Rpd = 220Ω Rev.: C 1 Amendment: /0 Issue Date: May 2006 SY88703V Micrel, Inc. PACKAGE/ORDERING INFORMATION Ordering Information /EN 1 10 VCC DIN 2 9 DOUT /DIN 3 8 /DOUT Part Number Package Type Operating Range Package Marking Lead Finish 7 LOS SY88703VKC K10-1 Commercial 703V Sn-Pb 6 GND SY88703VKCTR(1) K10-1 Commercial 703V Sn-Pb SY88703VKG K10-1 Industrial 703V with Pb-Free bar-line indicator Pb-Free NiPdAu SY88703VKGTR(1) K10-1 Industrial 703V with Pb-Free bar-line indicator Pb-Free NiPdAu VREF 4 LOSLVL 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 LOSLVL Input 6 GND Ground 7 LOS Open-collector TTL Output 8 /DOUT PECL Output Complementary data output. 9 DOUT PECL Output True data output. 10 VCC Power Supply Positive power supply. M9999-052406 [email protected] or (408) 955-1690 Pin Function Enable: Deasserts true data output when high. Reference voltage. Loss-of-Signal Level Set: A voltage between VCC and VREF on this pin sets the threshold for the data input amplitude at which LOS will be asserted. Device ground. Loss-of-Signal: Asserts high when the data input amplitude falls below the threshold set by LOSLVL. Requires an external pull-up resistor of 2.5kΩ. 2 SY88703V 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 LOSLVL Voltage ......................................................0 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 LOSLVL LOSLVL 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 VOL LOS Output LOW Level IOL = +2mA 0.5 V IOH LOS Output Leakage VOH = 5.5V 250 µA 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 –0.3 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. M9999-052406 [email protected] or (408) 955-1690 Typ 3 mA VCC–1.32 ±100 mV VCC V VCC–1.26 V SY88703V 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 LOS Hysteresis electrical signal 2 4.6 8 dB tOFF LOS Release Time 0.1 0.5 µs tON LOS 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 mVp-p VOD Differential Output Voltage Swing VSR LOS Sensitivity Range AV(Diff) Differential Voltage Gain B–3dB 3dB Bandwidth 700 S21 Single-Ended Small-Signal Gain 26 Note 1. 5 VID ≥ 18mVp-p VID = 5mVp-p 1500 400 5 50 38 32 TYPICAL OPERATING CHARACTERISTICS 100 VID (mVp-p) 70 60 50 40 VID (mVp-p) 3.3V TA = 25°C 622Mbps Pattern 223-1 90 80 30 20 10 0 100 90 80 70 5V LOS Assert and Deassert Levels vs. LOSLVL 5.0V TA = 25°C 622Mbps Pattern 223-1 60 50 40 30 20 10 0 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL (referenced to VCC) (V) M9999-052406 [email protected] or (408) 955-1690 4 0 mVp-p dB MHz Specification for packaged product only. 3.3V LOS Assert and Deassert Levels vs. LOSLVL mVp-p mVp-p -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 LOSLVL (referenced to VCC) (V) dB SY88703V Micrel, Inc. DETAILED DESCRIPTION Loss-of-Signal Level Set A programmable LOS level set pin (LOSLVL) sets the threshold of the input amplitude detection. Setting a voltage on LOSLVL between VCC and VREF sets this threshold. If desired, a resistor divider between VCC and VREF, as shown in Figure 5, also creates this threshold. The smaller the voltage difference from LOSLVL to VCC, the smaller the LOS sensitivity. Hence, larger input amplitude is required to deassert LOS. “Typical Operating Characteristics” shows the relationship between the input amplitude detection sensitivity and the LOSLVL voltage. The SY88703V 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 SY88703V generates an LOS output. LOSLVL sets the sensitivity of the input amplitude detection. Input Amplifier/Buffer Figure 2 shows a simplified schematic of the SY88703V's input stage. The high-sensitivity of the input amplifier allows signals as small as 5mVp-p to be detected and amplified. The input amplifier allows input signals as large as 1800mVp-p. Input signals are linearly amplified with a typically 38dB differential voltage gain. Since it is a limiting amplifier, the SY88703V outputs typically 1500mVp-p voltage-limited waveforms for input signals that are greater than 18mVp-p. Applications requiring the SY88703V to operate with high-gain should have the upstream TIA placed as close as possible to the SY88703V’s input pins to ensure the best performance of the device. Hysteresis The SY88703V provides typically 4.6dB LOS 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 SY88703V provides typically 2.3dB LOS optical hysteresis. As the SY88703V is an electrical device, this datasheet refers to hysteresis in electrical terms. With 6dB LOS hysteresis, a voltage factor of two is required to assert or deassert LOS. Output Buffer The SY88703V’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. Loss-of-Signal The SY88703V generates a chatter-free TTL LOS. A recommended 2.5kΩ pull-up resistor to VCC is required for proper operation, as shown in Figure 4. LOS is used to determine that the input amplitude is too small to be considered a valid input. LOS asserts high if the input amplitude falls below the threshold set by LOSLVL and deasserts low otherwise. LOS 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 4.6dB LOS hysteresis is provided to prevent chattering. M9999-052406 [email protected] or (408) 955-1690 5 SY88703V 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 Definition VCC VCC ESD STRUCTURE DOUT /DOUT DIN /DIN ESD STRUCTURE GND GND Figure 2. Input Structure Figure 3. Output Structure VCC R1 LOSLVL VCC LOS R2 2.5kΩ VREF Figure 4. LOS Output Structure Figure 5. LOSLVL Setting Circuit R2 Notes. LOSLVL = VCC – 1.32V + × 1.32V R1 + R2 R1 + R2 ≥ 2.6kΩ M9999-052406 [email protected] or (408) 955-1690 6 SY88703V Micrel, Inc. FUNCTIONAL BLOCK DIAGRAM DIN Limiting Amplifer DOUT PECL Buffer /DIN /DOUT VREF Enable VCC /EN Level Detect GND LOS LOSLVL DESIGN PROCEDURE Layout and PCB Design Since the SY88703V 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. M9999-052406 [email protected] or (408) 955-1690 The SY88703V’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 SY88703V Micrel, Inc. 10-PIN 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. © 2006 Micrel, Incorporated. M9999-052406 [email protected] or (408) 955-1690 8