microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? description the lx5255 is a low voltage differential (lvd) terminator designed to comply with the lvd termination specification in the spi-4 document. the lx5255 is specifically designed for lvd only applications. because the lx5255 supports only lvd, it has lower output capacitance than multimode terminators such as the lx5250. the lx5255 utilizes an industry standard lvd architecture. the individual high bandwidth drivers maximize channel separation, reduce channel-to-channel noise and cross talk to insure ultra320 performance. when the lx5255 is enabled, the differential sense (difsens) pin supplies a voltage between 1.2v and 1.4v. in application, the terminator diffb input is connect ed to the system difsens line. if there are no single ended or high voltage differential (hvd) devices attached to the system, the lvd output will be enabled. if the difsens line is low, indicating a single ended device, the lx5255 output will be hiz. if the difsens line is high, indicating a hvd device, the lx5255 output will be hiz. the lx5255 has a ttl compatible sleep/disable mode. applying a logic high to the disc pin puts the lx5255 in sleep mode. during sleep mode, power dissipation is reduced to a meager 5 a while also placing all outputs and the difsens function in a hiz state. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? compliant with spi-2 (ultra2), spi-3 (ultra160), and spi-4 (ultra320) ? 2.5pf maximum disabled output capacitance ? fast response, no external capacitors required ? 5a supply current in disconnect mode ? 30ma supply during normal operation ? logic command disconnects all termination lines ? difsens line driver ? current limit and thermal protection ? pin compatible with unitrode ucc5640 typical application lx5255 lx5255 + - + - lx5255 typical application package order info pw plastic tssop 24-pin t a ( c) rohs compliant / pb-free transition dc: 0442 0 to 70 lx5255cpw note: available in tape & reel. append the letters ?tr? to the part number. (i.e. LX5255CPW-TR) l l x x 5 5 2 2 5 5 5 5
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? absolute maximum ratings term power (v term )............................................................................................-0.3v to 7v signal line voltag e .............................................................................................-0.3v to 7v differential voltag e .............................................................................................-0.3v to 7v operating junction temperature.................................................................................. 150 c storage temperat ure rang e........................................................................... -65 c to 150 c peak package solder reflow temperature (40 second maximum exposure) . 260c (+0, -5) note: exceeding these ratings could cause damage to th e device. all voltages are with respect to ground. currents are positive into, ne gative out of specified terminal. thermal data pw 24l tssop t hermal r esistance -j unction to a mbient , ja 100c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the therma l performance of the device/pc-board system. all of the above assume no ambient airflow. ja can vary significantly depending on mounting technique. (see application notes section: thermal considerations) diffb/power up/power down function table outputs disc diffb status type quiescent current l l < 0.5v disable hi-z 8ma l 0.7v to 1.9v enable lvd 30ma l h > 2.4v disable hi-z 8ma h or open x disable hi-z 10a package pin out 1- 2+ 9+ nc 2 3 4 5 6 7 8 9 10 11 12 1 23 22 21 20 19 18 17 16 15 14 13 24 1+ 2- 3+ 3- 4+ 4- diffb difsens gnd 9- 8- 8+ 7- 7+ 6- 6+ 5- 5+ disc vterm pw p ackage (top view) nc ? no internal connection rohs / pb-free 100% matte tin lead finish recommended max operating conditions lx5255 parameter symbol min typ max units vterm v term 2.7 5.25 v signal line voltage 0 5.0 v disconnect input voltage 0 v term v operating junction temperature t j 0 70 c p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? electrical characteristics unless otherwise specified, the following specificati ons apply over the operat ing ambient temperature 0 c t a 70 c, vterm = 3.3v, and disconnect = 0v. lx5255 parameter symbol test conditions min typ max units ` lvd terminator section all term lines open 30 35 ma vterm supply current i cc disconnect > 2.0v 5 20 a common mode voltage v cm 1.125 1.25 1.375 v offset voltage (note 1) v os open circuit between (-) and (+) terminals 100 112 125 mv differential terminator impedance z d v out differential = -1v to +1v 100 105 110 ? common mode impedance z cm 0.5v to 2v 110 150 190 ? output capacitance (note 2) c o disconnect > 2.0v 3 pf mode change delay t df difsens = 1.4v to 0v 100 115 300 ms ` difsens section difsens output voltage v diff 1.2 1.3 1.4 v difsens output source current i diff difsens = 0v 5 15 ma difsens sink current i sink(diff) v term = 2.75v 20 200 a ` disconnect section disconnect threshold v th 0.8 2.0 v input current i ih disconnect = 0v 10 a note 1: open circuit failsafe voltage. note 2: guaranteed by design. e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? functional pin description p in n ame d escription 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- negative signal termination lines for lvd mode. 1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+ positive signal termination lines for lvd mode. v term power supply pin for terminator. connect to scsi bus vterm. must be decoupled by one 4.7 f low-esr capacitor for every th ree terminator devices. it is absolutely necessary to connect this pin to the decoupling capacitor through a very low impedance (big traces to pcb). keeping distances very short from the decoupling capacitors is somewhat layout dependent and some applications may benefit from high frequency decoupling with 0.1 f capacitors at v term pin. disc enables/disables terminator. see power down function table for logic levels . gnd terminator ground pin. connect to ground. difsens differential sense pin connected to syst em diffsens line. drives the scsi bus difsens line to 1.3v. diffb used to detect the scsi bus mode (se, lvd or hvd). should be connected to a 4.7uf capacitor to gnd, and a 50k ? resistor to the diffsens pin (see figure 2 on page 5). 5 block diagram difsens disc diffb latch window comp. + - power on & mode delay lvd se hvd 150 1.07 ma 1.07 ma 52.5 52.5 vterm lvd gnd lvd(-) lvd(+) 1 of 9 lines 10ma i-limited 1.3v source hvd se lvd hvd se 24 13 11 10 12 3 2 disc 1.25v disc figure 1 ? lx5255cpw block diagram p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? application 1- 1+ 9- 9+ vterm difsens diffb disc gnd nc* 1- 1+ 9- 9+ vterm difsens diffb disc gnd nc* 1- 1+ 9- 9+ vterm difsens diffb disc gnd nc* vterm difsens diffb disc gnd nc* 1- 1+ 9- 9+ vterm difsens diffb disc gnd nc* 1- 1+ 9- 9+ vterm difsens diffb disc gnd nc* 1- 1+ 9- 9+ data lines (9) data lines (9) control lines (9) host peripheral 50k 4.7uf 4.7uf 4.7uf 4.7uf 4.7uf 4.7uf 4.7uf 4.7uf pin 1 pin 1 pin 1 pin 1 pin 1 pin 1 disconnect disconnect termpower termpower 50k * the capacitor on pin 1 can be placed on the lx5255pcw to be pin co mpatible with other devices. this capacitor is not required . 4.7uf 4.7uf lx5255 lx5255 lx5255 lx5255 lx5255 lx5255 figure 2 ? suggested microsemi lx5255 univ ersal application schematic a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? mechanical drawings pw 24-pin thin small shrink outline (tssop) c 1 2 3 p d e f a g h l b m seating plane m illimeters i nches dim min max min max a 0.85 0.95 0.033 0.037 b 0.19 0.30 0.007 0.012 c 0.09 0.20 0.0035 0.008 d 7.70 7.90 0.303 0.311 e 4.30 4.50 0.169 0.177 f 0.65 bsc 0.025 bsc g 0.05 0.15 0.002 0.005 h ? 1.10 ? .0433 l 0.50 0.75 0.020 0.030 m 0 8 0 8 p 6.25 6.55 0.246 0.256 *lc ? 0.10 ? 0.004 * lead coplanarity note: 1. dimensions do not include mold flash or protrusions; thes e shall not exceed 0.155mm(.006?) on any side. lead dimension shal l not include solder coverage. m m e e c c h h a a n n i i c c a a l l s s
microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 1.1, 2006-02-27 www. microsemi . com lx5255 9-line lvd scsi terminator p r oduction data sheet tm ? notes production data ? information contained in this document is proprietary to microsemi and is current as of publication date. this document may not be modified in any way without the express written consent of microsemi. product processing does not necessarily include testing of all parameters. microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. n n o o t t e e s s
|
