UCC5620 27-Line SCSI Terminator FEATURES DESCRIPTION • Complies with SCSI, SCSI-2, SCSI-3, SPI and FAST-20 (Ultra) Standards UCC5620 provides 27 lines of active termination for a SCSI (Small Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the cable. • 2.5pF Channel Capacitance during Disconnect • 100mA Supply Current in Disconnect Mode • 4V To 7V Operation • 110 Termination • Completely Meets SCSI Hot Plugging • –900mA Sourcing Current for Termination • +500mA Sinking Current for Active Negation • Logic Command Disconnects all Termination Lines • Trimmed Impedance to 5% • Current Limit and Thermal Shutdown Protection The UCC5620 is ideal for high performance 5V SCSI systems. During disconnect the supply current is typically only 100µA, which makes the IC attractive for lower powered systems. The UCC5620 is designed with a low channel capacitance of 2.5pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus. The power amplifier output stage allows the UCC5620 to source full termination current and sink active negation current when all termination lines are actively negated. The UCC5620, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at the teminating channels with VTRMPWR = 0V or open. Internal circuit trimming is utilized, first to trim the 110Ω impedance, and then most importantly, to trim the output current as close to the maximum SCSI-3 specification as possible, which maximizes noise margin in fast SCSI operation. Other features include thermal shutdown and current limit. This device is offered in low thermal resistance versions of the industry standard 36-Pin Wide Body QSOP (MWP) and 48-Pin LQFP (FQP). Consult QSOP-36 or LQFP-48 packaging diagram for exact dimensions. BLOCK DIAGRAM Circuit Design Patented SLUS287A - OCTOBER 1999 UDG-96109 UCC5620 ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAM Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A Storage Temperature . . . . . . . . . . . . . . . . . . . −65 C to +150 C Junction Temperature . . . . . . . . . . . . . . . . . . . −55 C to +150 C Lead Temperature (Soldering, 10 Sec.). . . . . . . . . . . . . +300 C SSOP-36 (Top View) MWP Package Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. LFQP-48 (Top View) FQP Package HS/GND HS/GND LINE 9 LINE 23 HS/GND LINE 8 LINE 7 LINE 6 LINE 5 LINE 22 LINE 24 N/C 48 47 46 40 39 38 1 37 36 LINE 21 LINE 25 2 35 LINE 20 LINE 26 3 34 LINE 19 LINE 27 4 33 REG HS/GND 5 32 HS/GND HS/GND 6 31 HS/GND HS/GND 7 30 HS/GND HS/GND 8 29 HS/GND N/C 9 28 TRMPWR DISCNCT1 10 27 LINE 18 LINE 10 11 26 LINE 17 LINE 11 12 13 14 25 LINE 16 15 45 16 44 43 42 N/C 17 18 19 41 20 21 22 23 LINE8 1 36 LINE7 LINE9 2 35 LINE6 LINE23 3 34 LINE5 LINE24 4 33 LINE22 LINE25 5 32 LINE21 LINE26 6 31 LINE20 LINE27 7 30 LINE19 GND 8 29 REG GND 9 28 GND GND 10 27 GND DISCNCT 11 26 GND LINE10 12 25 TRMPWR LINE11 13 24 LINE18 LINE12 14 23 LINE17 LINE13 15 22 LINE16 LINE14 16 21 LINE15 LINE1 17 20 LINE4 LINE2 18 19 LINE3 24 N/C LINE 12 LINE 15 LINE 4 LINE 13 LINE 14 HS/GND LINE 3 LINE 2 LINE 1 HS/GND HS/GND ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C, TRMPWR = 4.75V, DISCNCT = 0V, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS All Termination Lines = Open 1 2 mA All Termination Lines = 0.2V 630 650 mA DISCNCT = TRMPWR 100 200 µA Supply Current Section TRMPWR Supply Current Power Down Mode 2 UCC5620 ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C, TRMPWR = 4.75V, DISCNCT = 0V, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Output Section (Termination Lines) Termination Impedance (Note 3) 104.5 110 115.5 Ω Output High Voltage (Note 1) 2.6 2.8 3.0 V VLINE = 0.2V, TJ = 25°C −22.1 −23.3 −24 mA VLINE = 0.2V −20.7 −23.3 −24 mA VLINE = 0.2V, TRMPWR = 4V, TJ = 25°C (Note 1) −21 −23 −24 mA VLINE = 0.2V, TRMPWR = 4V (Note 1) −20 −23 −24 mA Max Output Current −22.4 mA Output Leakage DISCNCT = 2.4V, TRMPWR = 0V to 5.25V 10 400 nA Output Capacitance DISCNCT = 2.4V (Note 2) 2.5 4 pF 2.8 3.0 V 0.4 0.8 V VLINE = 0.5V Regulator Section Regulator Output Voltage 2.6 Drop Out Voltage All Termination Lines = 0.2V Short Circuit Current VREG = 0V −650 −900 –1300 mA Sinking Current Capability VREG = 3.5V 300 500 900 mA Thermal Shutdown 170 C° Thermal Shutdown Hysteresis 10 C° Disconnect Section Disconnect Threshold Input Current 0.8 DISCNCT = 0V 1.5 2.0 V –20 –60 µA Note 1:Measuring each termination line while other 26 are low (0.2V). Note 2:Guaranteed by design. Not 100% tested in production. Note 3:Tested by measuring IOUT with VOUT = 0.2V and VOUT with no load, then calculate: Z = (VOUT N . L.− 0 . 2V ) IOUT at 0 . 2V PIN DESCRIPTIONS DISCNCT: Taking this pin high or leaving it open causes all channels to become high impedance, and the chip to go into low-power mode; a low state allows the channels to provide normal termination. GND: Ground reference for the IC. LINE1 - LINE27: 110Ω termination channels. REG: Output of the internal 2.7V regulator. TRMPWR: Power for the IC. 3 UCC5620 APPLICATION INFORMATION UCC5620 TRMPWR TRMPWR DISCNCT 4.7µF REG L1 L27 DATA BYTES 1 AND 2 +2 PARITY BITS 4.7µF CONTROL BITS TO DRIVERS AND RECEIVERS TO SCSI BUS Figure 1. Typical Wide SCSI Bus Configuration Using the UCC5620 UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 FAX (603) 424-3460 4 UDG-98188