SY88953ALMG-TR

SY88953AL 3.3V 10.7Gbps CML Limiting Post Amplifier with TTL SD and /SD General Description Features The SY88953AL high-speed, 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 SY88953AL quantizes these signals and outputs CML level waveforms. • • • • • • The SY88953AL operates from a single +3.3V power supply over temperatures ranging from –40°C to +85°C. With its wide bandwidth and high gain, the SY88953AL can take signals with data rates up to 10.7Gbps and as small as 5mVPP and amplify them to drive devices with CML inputs. The SY88953AL outputs TTL signal-detect (SD and /SD) signals. 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. /SD is the complementary output of SD. /SD can be fed back to the enable (/EN) input to maintain output stability under a loss-of-signal (LOS) condition. /EN deasserts the true output signal without removing the input signal. Typically 6dB SD hysteresis is provided to prevent chattering. The SY88953AL also includes an input adjustment to correct pulse-width distortion. Single 3.3V power supply Up to 10.7Gbps operation 700mVPP output swing with 25ps edge rates (typically) 28dB voltage gain with 5mVPP input sensitivity On-chip 50Ω I/O termination Programmable signal detect (SD and /SD) with 6dB hysteresis • Chatter-free OC-TTL SD and /SD outputs with internal 5kΩ pull-up resistors can feedback to TTL enable (/EN) input • Available in a tiny 3mm x 3mm 16-pin QFN package or die • Low power (62mA) Applications • • • • • OC-192 SDH/SONET 10G Ethernet/Fibre Channel receivers Up to 10.7Gbps proprietary link XFP transceivers Line driver/receiver threshold Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Typical Application Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com August 29, 2013 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Ordering Information Part Number SY88953ALMG (1) SY88953ALMGTR Package Marking Operating Range Package Lead Finish 953A with Pb-Free bar-line indicator Industrial 16-Pin QFN Pb-Free, NiPdAu 953A with Pb-Free bar-line indicator Industrial 16-Pin QFN Pb-Free, NiPdAu Note: 1. Tape and reel. Pin Configuration 16-Pin QFN Pin Description Pin Number Pin Name Type 1 DIN Data input 2, 3, 10, 11 VCC Power supply 4 /DIN Data input 5 VTHN Input 6 SD Open-collector TTL output with internal 5kΩ pull-up resistor Signal detect asserts high when the data input amplitude rises above the threshold set by SDLVL. 7 /SD Open-collector TTL output with internal 5kΩ pull-up resistor Inverted signal detect asserts low when the data input amplitude rises above the threshold set by SDLVL. 8, 13, EP GND Ground Device ground. Exposed pad must be soldered to PCB ground for proper electrical and thermal performance. 9 /DOUT CML output Complementary data output. 12 DOUT CML output True data output. 14 SDLVL Input 15 /EN TTL input default is high 16 VTHP Input August 29, 2013 Pin Function True data input with 50Ω resistor to VCC. Positive power supply. Complementary data input with 50Ω resistor to VCC. /DIN DC threshold adjustment pin. Signal detect level set: A resistor from this pin to VCC set the threshold for the data input amplitude at which SD asserts. Enable: Deasserts true data output when high. DIN DC threshold adjustment pin. 2 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Absolute Maximum Ratings(2) Operating Ratings(3) Supply Voltage (VCC) .................................... –0.5V to +4.0V Data Input Voltage (DIN, /DIN) ...................................... (VCC–1.0V) to (VCC+0.5V) Data Output Voltage (DOUT, /DOUT) ................................. (VCC–1.0V) to (VCC+0.5V) /EN Voltage ........................................................... 0V to VCC SD, /SD Current ............................................................ 5mA SDLVL Voltage ......................................... (VCC–1.3V) to VCC Storage Temperature (TS) ......................... –65°C to +150°C Supply Voltage (VCC) .................................... +3.0V to +3.6V Ambient Temperature (TA) .......................... –40°C to +85°C Junction Temperature (TJ) ........................ –40°C to +120°C (4) Junction Thermal Resistance QFN-16 (θJA) Still-Air ......................................... 59°C/W QFN-16 (θJB) Still-Air ......................................... 32°C/W DC Electrical Characteristics(5) VCC = 3.0V to 3.6V; RLOAD = 50Ω to VCC; 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 VSDLVL SDLVL voltage VIH /EN input HIGH voltage VIL /EN input LOW voltage IIH /EN input HIGH current VIN = VCC IIL /EN input LOW current VIN = 0.5V VOH SD, /SD output HIGH level VOL SD, /SD output LOW level IOL = +2mA VOH Output HIGH voltage 50Ω to VCC output load VCC−0.02 VOL Output LOW voltage 50Ω to VCC output load VCC−0.40 VOFFSET Differential output offset ZO Single-ended output impedance ZIN Single-ended input impedance Typ. Max. Units 62 85 mA VCC V VCC−1.3 2.0 V 0.8 V 20 μA −0.3 mA 2.4 V 45 0.5 V VCC−0.005 VCC V VCC−0.35 VCC−0.24 V ±80 mV 55 Ω 50 Notes: 2. Exceeding the absolute maximum ratings may damage the device. 3. The device is not guaranteed to function outside its operating ratings. 4. Exposed pad must be soldered to PCB’s ground plane. 5. Specification for packaged product only August 29, 2013 3 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL AC Electrical Characteristics VCC = 3.0V to 3.6V; RLOAD = 50Ω to VCC; 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 6 8 dB PSRR Power supply rejection ratio 35 tOFF SD, /SD release time 0.1 0.5 μs tON SD, /SD assert time 0.2 0.5 μs tr/tf Output rise/fall time 25 35 ps VID Differential input voltage swing 1800 mVPP VOD Differential output voltage swing 800 mVPP VSR SD sensitivity range 50 mVPP LOSAL Low LOS assert level RLOSLVL = 10kΩ, Note 6 11 mVPP LOSDL Low LOS de-assert level RLOSLVL = 10kΩ, Note 6 17 mVPP HSYL Low LOS hysteresis RLOSLVL = 10kΩ, Note 7 3.5 dB LOSAM Medium LOS assert level RLOSLVL = 5kΩ, Note 6 17 mVPP LOSDM Medium LOS de-assert level RLOSLVL = 5kΩ, Note 6 26 mVPP HSYM Medium LOS hysteresis RLOSLVL = 5kΩ, Note 7 3.5 dB LOSAH High LOS assert level RLOSLVL = 100Ω, Note 6 45 mVPP LOSDH High LOS de-assert level RLOSLVL = 100Ω, Note 6 68 mVPP HSYH High LOS hysteresis RLOSLVL = 100Ω, Note 7 3.5 dB S21 Single-ended small-signal gain 16 22 dB AOV(Diff) Differential voltage gain 22 28 dB B-3dB 3dB Bandwidth 7.5 GHz VID ≥ 50mVPP 5 600 700 5 dB Notes: 6. See “Typical Operating Characteristics” for the graph that demonstrates how to choose a particular RLOSLVL for a particular LOS assert and its associated de-assert amplitude. 7. This specification defines electrical hysteresis as 20log(LOS de-assert/LOS assert). The ratio between optical hysteresis and electrical hysteresis is found to vary between 1.5 and 2, depending on the level of received power and ROSA characteristics. August 29, 2013 4 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Typical Operating Characteristics 10.7Gbps, VIN = 5mVPP, VTH Open (20ps/div) 10.7Gbps, VIN = 10mVPP, VTH Open (20ps/div) 10.7Gbps, VIN = 20mVPP, VTH = 1.0V (20ps/div) 10.7Gbps, VIN = 20mVPP, VTH = 1.5V (20ps/div) SY88953AL LOSA, LOSD vs. RLOSlvl SY88953AL Hysteresis vs. RLOSlvl August 29, 2013 5 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Functional Diagram The SY88953AL’s ground pins should be connected to the circuit board ground. Use multiple PCB vias close to the part to connect to ground. Avoid long, inductive runs that can degrade performance. Design Procedure Layout and PCB Design Because the SY88953AL 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 large swing outputs to the input via the power supply. August 29, 2013 6 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Threshold Adjustment The SY88953AL’s duty cycle can be controlled by forcing an offset at either input using VTHP or VTHN. Typically, only one of the inputs is required to be adjusted, depending on the required direction of the pulse width adjustment. The SY88953AL implements current source based offset control of the inputs. The Typical Operating Characteristics section shows the offset applied to the input for a given VTH voltage. This feature is disabled by simply setting VTH to GND. Functional Description The SY88953AL high-speed limiting post amplifier operates from a single +3.3V power supply over temperatures from –40°C to +85°C. Signals with data rates up to 10.7Gbps and as small as 5mVPP can be amplified. Figure 1 shows the allowed input voltage swing. The SY88953AL generates SD and /SD outputs. SDLVL sets the sensitivity of the input amplitude detection. The SY88953AL also includes an input threshold adjustment to correct pulse width distortion. Output Buffer The SY88953AL’s CML output buffer is designed to drive 50Ω lines. The output buffer requires appropriate termination for proper operation. An external 50Ω resistor to VCC for each output pin provides this. Figure 3 shows a simplified schematic of the output stage and includes an appropriate termination method. Of course, driving a downstream device that is internally terminated with 50Ω to VCC eliminates the need for external termination. As noted in the previous section, the amplifier outputs typically 700mVPP waveforms across 25Ω total loads. The output buffer thus switches typically 16mA tail-current. Figure 1. VIS and VID Definitions Input Amplifier/Buffer Figure 2 shows a simplified schematic of the SY88953AL’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 typical differential voltage gain of 28dB. Because it is a limiting amplifier, the SY88953AL outputs typically 700mVPP voltage-limited waveforms for input signals that are greater than 32mVPP. Applications requiring the SY88953AL to operate with high-gain should have the upstream TIA placed as close as possible to the SY88953AL’s input pins to ensure the best performance of the device. Figure 3. Output Structure Signal-Detect The SY88953AL generates chatter-free signal-detect (SD and /SD) open-collector TTL outputs with internal 5kΩ pull-up resistors 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 SDLVL and deasserts low otherwise. /SD is the complementary output of SD. /SD asserts low if the input amplitude rises Figure 2. Input Structure August 29, 2013 7 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL above the threshold set by SDLVL and deasserts high 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. Figure 5. SDLVL Setting Circuit Figure 4. SD, /SD Output Structure Hysteresis The SY88953AL provides typically 6dB SD electrical hysteresis. By definition, a power ratio measured in dB is 2 10log(power ratio). Power is calculated as V IN/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 SY88953AL provides typically 3dB SD optical hysteresis. As the SY88953AL 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 de-assert SD. Signal-Detect Level Set A programmable signal-detect 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 VCC−1.3V. The external resistor creates a voltage divider between VCC and VCC−1.3V 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. The Typical Operating Characteristics section shows the relationship between the input amplitude detection sensitivity and the SDLVL voltage. August 29, 2013 8 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690 Micrel, Inc. SY88953AL Package Information(8) PCB Thermal Consideration for 16-Pin QFN Package (Always solder, or equivalent, the exposed pad to the PCB) Note: 8. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com. MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. 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 a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2013 Micrel, Incorporated. August 29, 2013 9 Revision 1.1 hbwhelp@micrel.com or (408) 955-1690