description 3.3v and 5v power supply options up to 2.5gbps 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 SY88923V 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 2.5gbps. signals as small as 5mvp-p can be amplified to drive devices with pecl inputs. the SY88923V generates a chatter-free loss of signal (los) open collector ttl output. the SY88923V incorporates a programmable level detect function to identify when the input signal has been lost. the los output will change from logic ?ow?to logic ?igh?when input signal is smaller than the swing set by los lvl . this information can be fed back to the en input of the device to maintain stability under loss of signal condition. using los lvl pin, the sensitivity of the level detection can be adjusted. the los lvl voltage can be set by connecting a resistor divider between v cc and v ref show in figure 3. figure 4, 5, 6, and 7 show the relationship between input level sensitivity and the voltage set on los lvl. the los output is a ttl open collector output that requires a pull-up resistor for proper operation, figure 1. features 5v/3.3v 2.5gbps high-speed limiting post amplifier SY88923V final applications 1.25gbps and 2.5gbps gigabit ethernet 531mbps, 1062mbps and 2.12gbps fibre channel 622mbps sonet gigabit interface converter 2.5gbps sdh/sonet 2.5gbps proprietary links pin configuration block diagram figure 1. los output with desired rise time SY88923V los 2k v cc 1 /en din /din vref loslvl 10 vcc dout /dout los gnd 9 8 7 6 2 3 4 5 msop k10-1 limiting amplifer ecl buffer gnd enable level detect /en los d in /d in v ref v cc los lv l d out /d out 1 rev.: b amendment: /0 issue date: august 2000
2 SY88923V micrel general the SY88923V is an integrated limiting amplifier intended for high-frequency fiber-optic applications. the circuit connects to typical trans-impedance amplifiers found within a fiber-optics link. the linear signal output from a trans- impedance amplifier can contain significant amounts of noise, and may vary in amplitude over time. the SY88923V 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. general description symbol rating value unit v cc power supply voltage 0 to +7.0 v d in , /d in input voltage 0 to v cc v d out , /d out output voltage (with 50 ? load) v cc 2.5 to v cc +0.3 v /en input voltage 0 to v cc v los lvl input voltage 0 to v cc v v ref output voltage v cc 2.0 to v cc v t a operating temperature range 40 to +85 c t store storage temperature range 55 to +125 c absolute maximum ratings (1) note: 1. permanent device damage may occur if absolute maximum ratings are exceeded. this is a stress rating only and functional oper ation is not implied at conditions other than those detailed in the operational sections of this data sheet. exposure to absolute maximum ratlng co nditions for extended periods may affect device reliability. pin type function d in data input data input /d in data input inverting data input los lvl input los limit set /en ttl input output enable (active low) los ttl output loss of signal indicator (open collector) (active high) gnd ground ground /d out pecl output inverting data output d out pecl output data output v cc power supply positive power supply v ref output reference voltage output for los level set (see fig. 3) pin names
3 SY88923V micrel t a = ?0 ct a = 0 ct a = +25 ct a = +85 c symbol parameter min. max. min. max. min. typ. max. min. max. unit i cc power supply 5v 40 40 30 40 45 ma current (1) 3.3v 40 40 28 40 45 i il /en input low current 0.3 (6) 0.3 (6) 0.3 (6) 0.3 (6) ma i ih /en input high current 20 (4) 20 (4) 20 (4) 20 (4) a 100 (5) 100 (5) 100 (5) 100 (5) v cmr common mode range gnd +2.0 v cc gnd +2.0 v cc gnd +2.0 v cc gnd +2.0 v cc v v offset differential output offset 100 100 17 100 100 mv los lvl los lvl level v ref v cc v ref v cc v ref v cc v ref v cc v v ol los output low level (2) 0.5 0.5 0.5 0.5 v i oh los output leakage (3) 100 100 100 100 ua v oh d out and /d out v cc 1085 v cc 880 v cc 1025 v cc 880 v cc 1025 v cc 955 v cc 880 v cc 1025 v cc 880 mv high output v ol d out and /d out v cc 1830 v cc 1555 v cc 1810 v cc 1620 v cc 1810 v cc 1705 v cc 1620 v cc 1810 v cc 1620 mv low output v ref reference supply v cc 1.38 v cc 1.26 v cc 1.38 v cc 1.26 v cc 1.38 v cc 1.32 v cc 1.26 v cc 1.38 v cc 1.26 v i ref v ref output current 0.8 0.5 0.8 0.5 0.8 0.5 0.8 0.5 ma v ih /en input high voltage 2.0 2.0 2.0 2.0 v v il /en input low voltage 0.8 0.8 0.8 0.8 v notes: 1. no output load 2. i ol = + 2ma 3. v oh = 5.5v dc electrical characteristics v cc = +5v 10% or +3.3v 10%, r load = 50 ? to v cc 2v 4. v in = 2.7v 5. v in = v cc 6. v in = 0.5v t a = ?0 ct a = 0 ct a = +25 ct a = +85 c symbol parameter min. max. min. max. min. typ. max. min. max. unit conditions psrr power supply (1) 35 db input referred, rejection ratio 55mhz v id input voltage range 5 1800 5 1800 5 1800 5 1800 mvp-p v od differential output 700 mv v id = 15mvp-p voltage swing (2) 300 mv v id = 5mvp-p t offl los release time (3) 0.5 0.5 0.1 0.5 0.5 s minimum input t onl los assert time (3) 0.5 0.5 0.2 0.5 0.5 s t offh los release time (4) 0.5 0.5 0.1 0.5 0.5 s maximum input v sr los sensitivity range 5 50 5 50 5 50 5 50 mvp-p 2 23 -1 pattern hys los hysteresis 2 8 2 8 2 4.6 8 2 8 db 2 23 -1 pattern t r , t f output rise/fall time 175 175 150 175 175 ps v id > 100mvp-p t rin ,t fin v id < 100mvp-p ac electrical characteristics v cc = +5v 10% or +3.3v 10%, r load = 50 ? to v cc 2v 3. input is a 200mhz square wave, tr < 300ps, 8mvp-p. 4. input is a 200mhz square wave, tr < 300ps, 1.8vp-p. notes: 1. input referred noise = rms output noise/low frequency gain. 2. input is a 622mhz square wave.
4 SY88923V micrel product ordering code ordering package operating code type range SY88923Vkc k10-1 commercial SY88923Vkctr k10-1 commercial output termination the SY88923V outputs must be terminated with a 50 ? load to v cc 2v (or thevenin equivalent). layout and pcb design since the SY88923V 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. design procedure r1 r2 v cc los lv l v ref figure 3. los lvl circuit 50 ? 50 ? 0.1 f 0.1 f 0.1 f d in+ d in v ref figure 2. differential input configuration the SY88923V 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. notes: los lvl = v cc -1.32v + r1 + r2 2.6k ? r2 1.32v r1 + r2
5 SY88923V micrel performance curve 0 10 20 30 40 50 60 70 80 90 100 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 input level (mvp-p) los lvl = v cc v (v) los assert and deassert levels vs los lvl 3.3v t a = 25 c 2.5gbps pattern 2 23 -1 figure 4. 0 10 20 30 40 50 60 70 80 90 100 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 input level (mvp-p) los lvl = v cc v (v) los assert and deassert levels vs los lvl 5.0v t a = 25 c 2.5gbps pattern 2 23 -1 figure 5. 0 10 20 30 40 50 60 70 80 90 100 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 input level (mvp-p) los lvl = v cc v (v) los assert and deassert levels vs los lvl 3.3v t a = 25 c 2.5gbps pattern 2 7 -1 figure 6. 0 10 20 30 40 50 60 70 80 90 100 0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2 input level (mvp-p) los lvl = v cc v (v) los assert and deassert levels vs los lvl 5.0v t a = 25 c 2.5gbps pattern 2 7 -1 figure 7.
6 SY88923V micrel 10 lead msop (k10-1) rev. 00
7 SY88923V micrel
8 SY88923V micrel micrel-synergy 3250 scott boulevard santa clara ca 95054 usa tel + 1 (408) 980-9191 fax + 1 (408) 914-7878 web 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 an y 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 pat ent right of micrel inc. ? 2000 micrel incorporated
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