MCCS142236 18-Bit Switchable Active SCSI-2 Bus Terminator (110Ω) With Voltage Regulator http://onsemi.com The MCCS142236 is a precision 18−bit switchable active SCSI−2 bus terminator with an on−board 2.85V regulator. When the Disconnect pin is LOW according to the truth table below, the MCCS142236 provides 110Ω ±5% precision resistor pull−ups to a 2.85V reference for termination of 18−bits in a SCSI−2 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. 18−BIT SWITCHABLE ACTIVE SCSI−2 BUS TERMINATOR • Complies With SCSI and SCSI−2 Standards • Pin Compatible With UC5601, UC5602 and UC5608 • For Opposite Disconnect Polarity See ON Semiconductor’s • • • • • • • • DW SUFFIX 28−LEAD SOIC WIDE CASE 751F−05 MCCS142238 18 Switchable 110Ω Terminating Resistors 4pF Channel Capacitance During Disconnect Fully Supports Active Negation (Sinks Minimum of 220mA) Built−In 2.85V Regulator With Low Dropout Voltage Very Low Supply Current When Resistors Are Disabled (30μA Max) −650mA Source Current Thermal Shutdown Protection Thin Profile Surface Mount Package: 28−Lead 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 (30μA), over 220mA of active negation current sink capability, and 4pF disconnect capacitance. In 8−bit SCSI applications (“A” cable), only one MCCS142236 is needed at each end of the SCSI cable in order to terminate the 18 active signal lines. In 16−bit WIDE SCSI applications (“P” 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 9−bit version of the MCCS142236. For information on “Power Dissipation for Active SCSI Terminators,” refer to ON Semiconductor Application Note AN1408/D, available through ON Semiconductor Fax System, or through the ON Semiconductor Literature Distribution Center. TRUTH TABLE © Semiconductor Components Industries, LLC, 2010 February, 2010 − Rev. 6 Disconnect Output 0 Terminated 1 Z 1 Publication Order Number: MCCS142236/D MCCS142236 Disconnect 1 28 GND Line1 2 27 Line18 Line2 3 26 Line17 Line3 4 25 Line16 Line4 5 24 Line15 Line5 6 23 Line14 GND* 7 22 GND* GND* 8 21 GND* GND* 9 20 GND* Line6 10 19 Line13 Line7 11 18 Line12 Line8 12 17 Line11 Line9 13 16 Line10 Termpwr 14 15 Reg MCCS142236 * Pins 7, 8, 9, 20, 21 and 22 are heat-sink grounds. Pin 28 is the signal ground. Figure 1. 28−Lead Pinout (Top View) Disconnect Input Application Result A. No Connection to Disconnect Disconnect input will be pulled “HIGH” internally, causing all outputs to be high impedance. B. Single Pole Switch to GND Disconnect input will be pulled “HIGH” internally when the switch is open, causing all outputs to be high impedance. Disconnect input will be held “LOW” when the switch is closed, providing 110Ω 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 “HIGH” input level. The supply source in this case could be Termpwr or VCC. D. Hardwired “High” The MCCS142236 will be permanently disconnected causing all outputs to be high impedance. E. Hardwired “Low” The MCCS142236 will be permanently connected providing 110Ω impedance to each of the bus lines. MAXIMUM RATINGS* Symbol Parameter Value Unit Termpwr DC Supply Voltage 7.0 V VLine Signal Line Voltage −1.0 to +7.0 V IREG Regulator Current tstg Storage Temperature Range 1 A −65 to +150 °C * Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the Recommended Operating Conditions. http://onsemi.com 2 MCCS142236 RECOMMENDED OPERATING CONDITIONS Symbol Parameter Min Max Unit 3.8 5.25 V DC Input Voltage (Disconnect Pin) 0 Termpwr V VLine Signal Line Voltage 0 5.0 V TA Operating Temperature Range 0 +70 °C tr, tf Input Rise/Fall Time 0 500 ns Termpwr DC Supply Voltage Vin ELECTRICAL CHARACTERISTICS (Unless otherwise stated, these specifications apply for TA = 0° to 70°C, Termpwr = 4.75V, Disconnect = Ground) Symbol Characteristic Min Typ Max Unit Condition Supply Current Section ITermpwr Termpwr Supply Current 15 410 27 465 mA All Termination Lines = Open All Termination Lines = 0.5V Ipd Power Down Mode Current 10 30 μA Disconnect = Open 104.5 110.0 115.5 Ω 2.8 2.85 3.0 V −24 mA Signal Line = 0.5V 1 μA Termpwr = 5.25V, Reg = Open, Disconnect = 4V 4.0 5.0 pF Disconnect = Open 2.85 3.0 V Signal Lines = 0V or 4V Output Section (Termination Lines) R110 Termination Impedance VOH Output HIGH Voltage Isource Source Current Capability per Line IOZ Output Leakage Current Signal Lines = 0 to 5.25V CO Output Capacitance (Note 2.) −19.9 Note 1. Regulator Section VReg Regulator Voltage Linereg Line Regulation 27 40 mV Signal Lines Open, Termpwr = 4V to 6V Loadreg Load Regulation 35 60 mV Signal Lines = 0V to 3V VDO Drop Out Voltage 0.7 0.9 V ILim Current Limit −450 −650 −850 mA Reg = 0V Isink Current Sink Capability 220 350 400 mA Reg = 3.5V Tshut Thermal Shutdown 2.8 150 Signal Lines = 0.5V °C Disconnect Section DTH Disconnect Threshold (Note 2.) IIL Input Leakage Current 1.1 1.3 1.7 V 100 120 μA 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, CL = 2.2μF, tr = tf = 6ns) Symbol Parameters 0°C to + 70°C Unit t(connect) Max Connect Time, High Impedance to Termination, Disconnect to Outputs 100 μs t(disconnect) Max Disconnect Time, Termination to High Impedance, Disconnect to Outputs 20 μs 3. Not production tested, guaranteed by design. http://onsemi.com 3 MCCS142236 Termpwr Reg 110Ω + Voltage Reference − 50kΩ Line 1 Shunt Control 110Ω Thermal Shutdown Line 18 Enable Logic Disconnect Charge Pump PATENTED CIRCUIT DESIGN Figure 2. MCCS142236 Block Diagram 2.2μF 2.2μF Termpwr Termpwr Reg Reg 2.2μF Disconnect MCCS142236 Line 18 2.2μF 0.1μF Disconnect 0.1μF Line 1 MCCS142236 Line 1 Line 18 TO RECEIVERS TO RECEIVERS BUS DRIVER BUS DRIVER TO RECEIVERS TO RECEIVERS BUS DRIVER BUS DRIVER SCSI CABLE Figure 3. Typical SCSI Bus Configuration Using the MCCS142236 30Ω Terminated Reg 80Ω Output High Impedance 4.0pF Figure 4. Output Impedance Model http://onsemi.com 4 MCCS142236 PACKAGE DIMENSIONS DW SUFFIX PLASTIC SOIC PACKAGE CASE 751F−05 ISSUE G −X− 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. D 28 15 H E 0.25 M Y M −Y− 1 DIM A A1 B C D E G H L M 14 PIN 1 IDENT A L 0.10 G B 0.025 M T X S A1 Y −T− SEATING PLANE MILLIMETERS MIN MAX 2.35 2.65 0.13 0.29 0.35 0.49 0.23 0.32 17.80 18.05 7.40 7.60 1.27 BSC 10.05 10.55 0.41 0.90 0_ 8_ C M S ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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