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 (micrel-synergy laser diode driver and controller) available in a tiny 10-pin (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 5mvp-p 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 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 los lvl . the los lvl voltage can be set by connecting a resistor divider between v cc and v ref as shown in figure 3. figure 4 and 5 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 1.25gbps high-speed limiting post amplifier SY88903V final applications 1.25gbps gigabit ethernet 531mbps and 1062mbps fibre channel 622mbps sonet gigabit interface converter pin configuration block diagram figure 1. los output with desired rise time SY88903V los 2k v cc 1 /en d in /d in v ref los lv l 10 v cc d out /d out los gnd 9 8 7 6 2 3 4 5 msop k10-1 limiting amplifer ecl buffer d in d in v ref v cc gnd los lv l enable level detect d out d out en los 1 rev.: a amendment: /1 issue date: july 2000
2 SY88903V final micrel general 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. 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 ?.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 ?0 to +85 c t store storage temperature range ?5 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 SY88903V final 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 current (1) 40 40 30 40 42 ma i il /en input low current ?.3 (6) ?.3 (6) ?.3 (6) ?.3 (6) ?a i ih /en input high current ?0 (4) ?0 (4) 20 (4) ?0 (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 ? cc gnd +2.0 v cc v v offset differential output offset 100 100 100 100 mv los lvl los lvl level v ref v cc v ref v cc v ref ? 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) 250 250 250 250 a 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 ?.8 0.5 ?.8 0.5 ?.8 0.5 ?.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, t a = ?0 c to +85 c 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 t r, t f output rise/fall time 260 260 260 260 ps v id > 100mvp-p t rin ,t fin v id < 100mvp-p v od differential output 600 mv v id = 15mvp-p voltage swing (2) 200 mvv id = 5mvp-p t offl los release time (3) 0.5 0.5 0.1 0.5 0.5 s minimum input t offh los release time (4) 0.5 0.5 0.1 0.5 0.5 s maximum input t onl los assert time (3) 0.5 0.5 0.2 0.5 0.5 s 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 ac electrical characteristics v cc = +5v 10% or +3.3v 10%; r load = 50 ? to v cc -2v, t a = ?0 c to +85 c 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 SY88903V final micrel product ordering code ordering package operating code type range SY88903Vkc k10-1 commercial SY88903Vkctr k10-1 commercial output termination the SY88903V outputs must be terminated with a 50 ? load to v cc ?2v (or thevenin equivalent). 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. design procedure figure 3. los lvl circut figure 2. differential input configuration 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. los lvl v ref r1 r2 v cc d in d in + v ref 50 50 0.1f 0.1f notes: los lvs = v cc -1.32v + r1 + r2 2.6k ? r2 1.32v r1 + r2
5 SY88903V final 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) loslvl vcc v los assert and deassert levels vs los lvl 3.3v t a = 25 c 1.25gbps pattern 2 7 -1 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) loslvl vcc v los assert and deassert levels vs los lvl 5.0v t a = 25 c 1.25gbps pattern 2 7 -1 figure 4. 3.3v los assert and deassert levels vs. los lvl figure 5. 5.0v los assert and deassert levels vs. los lvl
6 SY88903V final micrel 10 lead msop (k10-1) rev. 00 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. ? 1999 micrel incorporated
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