18-bit switchable active scsi-2 bus terminator (110 w ) with voltage regulator the mccs142236 ? is a precision 18bit switchable active scsi2 bus terminator with an onboard 2.85v regulator. when the disconnect pin is low according to the truth table below, the mccs142236 provides 110 w 5% precision resistor pullups to a 2.85v reference for termination of 18bits in a scsi2 standard bus system interface. when the disconnect pin is high, the device outputs are in the high impedance state on all 18 bits. the regulator is also turned off, greatly reducing standby power. even with no termpwr applied, the outputs remain in the high impedance state. ? complies with scsi and scsi2 standards ? pin compatible with uc5601, uc5602 and uc5608 ? for opposite disconnect polarity see on semiconductor's mccs142238 ? 18 switchable 110 w terminating resistors ? 4pf channel capacitance during disconnect ? fully supports active negation (sinks minimum of 220ma) ? builtin 2.85v regulator with low dropout voltage ? very low supply current when resistors are disabled (30 m a max) ? 650ma source current ? thermal shutdown protection ? thin profile surface mount package: 28lead soic the regulator has a guaranteed dropout voltage of less than 900mv, allowing regulation of supply voltages less than 4.0v. the mccs142236 is protected by thermal shutdown. other features include low disconnect current (30 m a), over 220ma of active negation current sink capability, and 4pf disconnect capacitance. in 8bit scsi applications (aao cable), only one mccs142236 is needed at each end of the scsi cable in order to terminate the 18 active signal lines. in 16bit wide scsi applications (apo cable), either two mccs142236s, one each of the mccs142236 and mccs142237, or three mccs142237s would be needed at each end of the scsi cable in order to properly terminate the 27 active signal lines. the mccs142237 is a 9bit version of the mccs142236. for information on apower dissipation for active scsi terminators,o refer to on semiconductor application note an1408/d, available through on semiconductor fax system, or through the on semiconductor literature distribution center. truth table disconnect output 0 terminated 1 z on semiconductor ? semiconductor components industries, llc, 2001 august, 2001 rev. 4 1 publication order number: mccs142236/d mccs142236 18bit switchable active scsi2 bus terminator dw suffix 28lead wide soic package case 751f05
mccs142236 http://onsemi.com 2 figure 1. 28lead pinout (top view) 1 disconnect 2 line1 3 line2 4 line3 5 line4 6 line5 7 gnd* 8 gnd* 9 gnd* 10 line6 11 line7 12 line8 13 line9 14 termpwr 28 27 26 25 24 23 22 21 20 19 18 17 16 15 gnd line18 line17 line16 line15 line14 gnd* gnd* gnd* line13 line12 line11 line10 reg mccs142236 * pins 7, 8, 9, 20, 21 and 22 are heat-sink grounds. pin 28 is the signal ground. disconnect input application result a. no connection to disconnect disconnect input will be pulled ahigho internally, causing all outputs to be high impedance. b. single pole switch to gnd disconnect input will be pulled ahigho internally when the switch is open, causing all outputs to be high impedance. disconnect input will be held alowo when the switch is closed, providing 110 w impedance to each of the bus lines. c. double pole switch between supply and gnd this is a more expensive way to accomplish application b above. it is more economical to allow the internal pullup to provide the ahigho input level. the supply source in this case could be termpwr or v cc . d. hardwired ahigho the mccs142236 will be permanently disconnected causing all outputs to be high impedance. e. hardwired alowo the mccs142236 will be permanently connected providing 110 w impedance to each of the bus lines. maximum ratings* symbol parameter value unit termpwr dc supply voltage 7.0 v v line signal line voltage 1.0 to +7.0 v i reg regulator current 1 a t stg storage temperature range 65 to +150 c * maximum ratings are those values beyond which damage to the device may occur. functional operation should be restricted to t he recommended operating conditions.
mccs142236 http://onsemi.com 3 recommended operating conditions symbol parameter min max unit termpwr dc supply voltage 3.8 5.25 v v in dc input voltage (disconnect pin) 0 termpwr v v line signal line voltage 0 5.0 v t a operating temperature range 0 +70 c t r , t f input rise/fall time 0 500 ns electrical characteristics (unless otherwise stated, these specifications apply for t a = 0 to 70 c, termpwr = 4.75v, disconnect = ground) symbol characteristic min typ max unit condition supply current section i termpwr termpwr supply current 15 410 27 465 ma all termination lines = open all termination lines = 0.5v i pd power down mode current 10 30 m a disconnect = open output section (termination lines) r110 termination impedance 104.5 110.0 115.5 w v oh output high voltage 2.8 2.85 3.0 v note 1. i source source current capability per line 19.9 24 ma signal line = 0.5v i oz output leakage current signal lines = 0 to 5.25v 1 m a termpwr = 5.25v, reg = open, disconnect = 4v c o output capacitance (note 2.) 4.0 5.0 pf disconnect = open regulator section v reg regulator voltage 2.8 2.85 3.0 v signal lines = 0v or 4v line reg line regulation 27 40 mv signal lines open, termpwr = 4v to 6v load reg load regulation 35 60 mv signal lines = 0v to 3v v do drop out voltage 0.7 0.9 v signal lines = 0.5v i lim current limit 450 650 850 ma reg = 0v i sink current sink capability 220 350 400 ma reg = 3.5v t shut thermal shutdown 150 c disconnect section d th disconnect threshold (note 2.) 1.1 1.3 1.7 v i il input leakage current 100 120 m a disconnect = 0v 1. measured with one output high and all other signal lines open. 2. not production tested, guaranteed by design. ac characteristics (note 3., reg = 2.85, c l = 2.2 m f, t r = t f = 6ns) symbol parameters 0 c to + 70 c unit t (connect) max connect time, high impedance to termination, disconnect to outputs 100 m s t (disconnect) max disconnect time, termination to high impedance, disconnect to outputs 20 m s 3. not production tested, guaranteed by design.
mccs142236 http://onsemi.com 4 figure 2. mccs142236 block diagram 110 w line 18 110 w line 1 patented circuit design enable logic disconnect shunt control 50k w charge pump termpwr reg + voltage reference thermal shutdown mccs142236 reg disconnect line 1 line 18 termpwr 0.1 m f bus driver figure 3. typical scsi bus configuration using the mccs142236 2.2 m f to receivers to receivers mccs142236 reg disconnect line 1 line 18 termpwr 0.1 m f bus driver to receivers to receivers 2.2 m f scsi cable 2.2 m f 2.2 m f figure 4. output impedance model 30 w 80 w reg output high impedance 4.0pf terminated bus driver bus driver
mccs142236 http://onsemi.com 5 package dimensions dw suffix plastic soic package case 751f05 issue g a1 1 15 14 28 b s x m 0.025 y s t m 0.25 y m seating plane a dim min max millimeters a 2.35 2.65 a1 0.13 0.29 b 0.35 0.49 c 0.23 0.32 d 17.80 18.05 e 7.40 7.60 g 1.27 bsc h 10.05 10.55 l 0.41 0.90 m 0 8 l c pin 1 ident d e h 0.10 x y g t m notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimensions d and e do not include mold protrusion 4. maximum mold protrusion 0.15 per side. 5. dimension b does not include dambar protrusion. allowable damber pr5otrusion shall not be 0.13 totatl in excess of b dimension at maximum material condition.
mccs142236 http://onsemi.com 6 notes
mccs142236 http://onsemi.com 7 notes
mccs142236 http://onsemi.com 8 on semiconductor and are trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to make changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. atypicalo parameters which may be provided in scill c data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body , or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indemnify and hold scillc and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthori zed use, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. publication ordering information japan : on semiconductor, japan customer focus center 4321 nishigotanda, shinagawaku, tokyo, japan 1410031 phone : 81357402700 email : r14525@onsemi.com on semiconductor website : http://onsemi.com for additional information, please contact your local sales representative. mccs142236/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 3036752175 or 8003443860 toll free usa/canada fax : 3036752176 or 8003443867 toll free usa/canada email : onlit@hibbertco.com n. american technical support : 8002829855 toll free usa/canada
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