Rev 1; 3/04 Ultra3 LVD/SE SCSI 14-Line Terminator Features The DS2127 Ultra3 LVD/SE SCSI terminator provides low-voltage differential (LVD)/single-ended (SE) terminations for 14 SCSI lines. Through the voltage on the DIFF_CAP pin, the device detects the types of drivers on the bus. If the device is connected in an LVD-only bus, the DS2127 provides LVD termination. If any single-ended devices are connected to the bus, the DS2127 uses SE termination. If any high-voltage differential (HVD) devices are connected to the bus, the DS2127 isolates itself from the SCSI bus. The mode change has a built-in delay that is determined by an integrated SPI-3 mode change filter/delay. The terminating resistors can also be disconnected from the bus by asserting the ISO pin. For the LVD termination, the DS2127 provides 14 precisely trimmed resistors. Each resistor is biased with two current sources to a fail-safe state. For SE termination, the DS2127 provides 14 precision 110Ω resistors and one regulator for active-negation bias. ♦ Fully Compliant with Ultra2, Ultra3, Ultra160, and Ultra320 SCSI Standards ♦ Provides LVD/SE Termination for 14 Signal Pairs ♦ Auto-Selection of LVD or SE Termination ♦ 5% Tolerance on SE and LVD Termination Resistance ♦ Low 3pF Power-Down Capacitance ♦ Built-In Mode-Change Filter/Delay ♦ On-Board Thermal-Shutdown Circuitry ♦ SCSI Bus Hot-Plug Compatible ♦ Fully Supports Actively Negated SE SCSI Signals Ordering Information Applications SCSI Array Backplane SCSI Cables PART TEMP RANGE DS2127 0°C to +70°C PINPACKAGE TOP MARK 48 LQFP DS2127 Pin Configuration 1 2 3 HS_GND HS_GND TPWR R14N R14P 4 5 6 7 HS_GND HS_GND HS_GND HS_GND 8 9 10 R1N R1P VREF 11 12 TOP VIEW R2P R2N R3P R3N R4P 13 48 14 47 15 46 16 45 17 44 R4N R5P R5N R6P R6N R7P R7N 18 43 19 42 DS2127 36 ISO 34 33 32 31 30 35 GND SE LVD 29 37 28 38 24 27 39 23 HS_GND HS_GND HS_GND HS_GND HS_GND HS_GND DIFF_CAP DIFFSENS 40 22 26 41 21 25 20 R13N R13P R12N R12P R11N R11P R10N R10P R9N R9P R8N R8P LQFP ______________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 DS2127 General Description DS2127 Ultra3 LVD/SE SCSI 14-Line Terminator ABSOLUTE MAXIMUM RATINGS Voltage Range on All Pins Relative to Ground ......-0.3V to +6.0V VREF Continuous Output Current....................................±200mA Operating Temperature Range...............................0°C to +70°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +160°C Soldering Temperature .......................................See IPC/JEDEC J-STD-020A Specification Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (TPWR = VTPWR(MIN) to VTPWR(MAX), TA = 0°C to +70°C, unless otherwise noted.) PARAMETER SYMBOL TPWR Operating Supply Range (Note 1) VTPWR CONDITIONS LVD SE MIN TYP MAX 2.7 3.3 5.5 4 5.0 5.5 UNITS V TPWR SUPPLY CURRENT TPWR Supply Current (All Lines Open) ITPWR_LVD LVD SCSI mode 32 mA ITPWR_SE SE SCSI mode 10 ITPWR_ISO ISO mode (terminators disabled) 750 µA 100 110 Ω 110 165 Ω LVD TERMINATION (Applies to each line pair, 1 to 14 in LVD mode) Differential-Mode Termination Resistance RDM Common-Mode Termination Resistance RCM RP and RN shorted together (VCM(MAX) = 2V, VCM(MIN) = 0.5V) Differential-Mode Bias VDM All lines open 100 125 mV Common-Mode Bias VCM RP and RN shorted together (Note 1) 1.15 1.25 1.35 V 104.5 110 115.5 Ω Signal level at 0.2V, all lines low -21 -24 Signal level at 0.5V -18 SE TERMINATION (Applies to single-ended terminators, 1 to 14 in SE mode) Single-Ended Mode Termination Resistance RSE Termination Current ISE SE Voltage Reference VREF Pin Leakage Single-Ended GND Resistance RSE = (VLX - 0.2) / ILX, where VLX = voltage at terminator pin with pin unloaded and ILX = current for each terminator pin with the pin forced to 0.2V 2.7 2.85 With ISO high RGND Measured at RP pins, I = 10mA -25.4 -22.4 20 mA 3.0 V 400 nA 60 Ω 3 pF TERMINATOR PIN CAPACITANCE Terminator Pin Capacitance CIN With ISO high (Note 2) VREF REGULATOR 1.25V Regulator Output Voltage VREF_LVD 0.5V ≤ VCM ≤ 2.0V, VCM applied to all RP and RN lines simultaneously 1.15 1.25 1.35 V 1.25V Regulator Short-Circuit Source Current ISOURCE VREF = 0V -375 -700 -1000 mA 1.25V Regulator Short-Circuit Sink Current ISINK VREF = 3.3V 170 300 700 mA 2 _____________________________________________________________________ Ultra3 LVD/SE SCSI 14-Line Terminator (TPWR = VTPWR(MIN) to VTPWR(MAX), TA = 0°C to +70°C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.0 2.5 % 2.7 2.85 3.0 V VREF REGULATOR VREF unloaded; vary TPWR from 2.7V to 5.5V 1.25V Regulator Line Regulation 2.85V Regulator 2.85V Regulator Short-Circuit Source Current VREF = 0V -375 -700 -1000 mA 2.85V Regulator Short-Circuit Sink Current VREF = 3.3V 170 300 700 mA 2.85V Regulator Line Regulation VREF unloaded; vary TPWR from 2.7V to 5.5V 1.0 2.5 % DIFFSENS OUTPUT DIFFSENS Driver Output Voltage VDSO -5mA ≤ IDIFFSENS ≤ 50µA 1.2 1.4 V DIFFSENS Driver Source Current IDSH VDIFFSENS = 0V -15 -5 mA IDSL VDIFFSENS = 2.75V 100 200 µA With ISO high, |VDIFFSENS| = 0.3V -3 +1 With ISO high, |VDIFFSENS - VTPWR| = 0.3V 1 3 DIFFSENS Driver Sink Current ILEAK, DIFFSENS Leakage (Note 3) LOW ILEAK, HIGH µA THERMAL SHUTDOWN Thermal-Shutdown Threshold For increasing temperature Thermal-Shutdown Hysteresis 130 °C 10 °C MODE CHANGE DELAY/FILTER Mode Change Delay tDELAY 0.66 Input Low Voltage VIL Input High Voltage VIH Input Current IIL 1.25 2.00 ms -0.3 +0.8 V 2.0 TPWR + 0.3 LOGICAL SIGNALS (ISO) V VCC = 3.3V -30 -10 µA STATUS BITS (LVD, SE) Source Current IOH VCC = 3.3V, VLOAD = 2.4V -4 -6 mA Sink Current IOL VCC = 3.3V, VLOAD = 0.4V 2 5 mA IL VIL = -0.3V DIFF_CAP Input Current -1 +1 µA VSEOR -0.3 +0.5 V DIFF_CAP LVD Operating Range VLVDOR 0.7 1.9 V DIFF_CAP HVD Operating Range VHVDOR 2.4 DIFF_CAP SE Operating Range VTPWR + 0.3 V Note 1: All voltages are referenced to ground. Note 2: Guaranteed by design and not production tested. Note 3: Room temperature only. _____________________________________________________________________ 3 DS2127 ELECTRICAL CHARACTERISTICS (continued) DS2127 Ultra3 LVD/SE SCSI 14-Line Terminator 2.15V DELAY/ FILTER DIFF_CAP LVD HVD 0.6V LVD LVD SE SE SE LVD SE HVD THERMAL SHUTDOWN ISO 1.30V DIFFSENS 10µA 110Ω CONTROL LOGIC 52Ω DS2127 R1N 124Ω BANDGAP REFGEN AND TRIM 1.25V (LVD) SE HVD/ISO LVD R1P 52Ω 2.15V 1.30V 0.6V 110Ω 2.85V (SE) 52Ω R14N 124Ω ALL SWITCHES UP ALL SWITCHES CENTER ALL SWITCHES DOWN 52Ω R14P VREF Figure 1. Block Diagram Pin Description PIN 1, 2, 11–24, 37–48 4 NAME FUNCTION Signal Termination. Connect to SCSI bus signal lines. Asserting ISO removes the terminators from the R_ _ P, R_ _ N SCSI bus. R_ _ P pins are the ground line for SE operation and the positive lines in differential mode. R_ _ N pins are the signal lines in SE operation and the negative lines in differential mode. 3 TPWR 4–9, 28–33 HS_GND 10 VREF 25 GND 26 SE 27 LVD Termination Power. Connect to the SCSI TERMPWR line and decouple with a ceramic 2.2µF capacitor. Heat-Sink Ground. Internally connected to the mounting pad. These pins must be connected to ground. These pins should be connected to a ground plane with the layout optimized for heat transfer. Regulator Output Voltage. This must be decoupled with a 4.7µF capacitor. Asserting ISO floats this output. A high-frequency capacitor (0.1µF) should also be placed on the VREF pin in applications that use fast rise/fall-time drivers. Signal Ground SE Mode Indicator. A high state indicates SE mode detected on SCSI bus. LVD Mode Indicator. A high state indicates LVD mode detected on SCSI. 34 DIFF_CAP DIFFSENSE Capacitor. Connect a 0.1µF capacitor for the DIFFSENSE filter. Input to detect the type of device (differential or single-ended) on the SCSI bus. 35 DIFFSENS DIFFSENSE. Output to drive the SCSI bus DIFFSENS line. 36 ISO Isolation Input. When pulled high, terminating resistors and biasing current sources are removed from the SCSI bus. When not connected to ground, the pin has a 10µA current source pulling the pin to the high state. _____________________________________________________________________ Ultra3 LVD/SE SCSI 14-Line Terminator DIFFSENS DIFFSENS 0.1µF 20kΩ 20kΩ 4.7µF 0.1µF DIFF_CAP TPWR 2.2µF DATA LINES (8) + PARITY DATA LINES (4) + PARITY ISO GND VREF GND DIFF_CAP VREF TPWR DIFF_CAP 2.2µF ISO DIFFSENS VREF DIFF_CAP 4.7µF 2.2µF CONTROL LINES (9) DATA LINES (4) ISO GND DS2127 TPWR TPWR 2.2µF DIFFSENS 4.7µF ISO DIFFSENS GND VREF 4.7µF Figure 2. Typical Operating Circuit Detailed Description The DS2127 provides dual-mode active terminators with auto-switching SE and LVD termination for 14 SCSI lines. The DIFFSENSE signal performs mode detection and selection. In LVD mode, the termination configuration is a y-type terminator with a 105Ω differential resistance and a 150Ω common-mode resistance. The termination resistor is biased with two current sources and the commonmode node is connected to a 1.25V voltage regulator. A fail-safe bias of 112mV is maintained when no drivers are connected to the SCSI bus. In SE mode, each negative signal input pin is connected to 2.85V through a 110Ω resistor. In HVD mode, the termination resistors are isolated from the SCSI bus and the resistor pins are left floating. The voltage regulator is powered down and the VREF pin is in a high-impedance state. The DIFF_CAP pin is connected to the SCSI DIFFSENSE line and monitors the voltage to determine the proper operating mode of the device. Any DIFFSENSE voltage below 0.5V indicates single ended; any DIFFSENSE voltage between 0.7V and 1.9V is LVD, and above 2.4V is an HVD SCSI. On power-up, the DS2127 assumes SE mode. If the voltage on the DIFF_CAP is between 0.7V and 1.9V, the device waits tDELAY before entering the LVD mode. The delay is the same when changing modes. A new mode change can start at any time after a previous mode change has been detected. Typically, four DS2127s are used in a SCSI bus segment. On two chips, the DIFF_CAP inputs at each end of the bus should be connected together. There should be a 50Hz noise filter implemented on DIFF_CAP at each end of the bus, as close as possible to the DIFF_CAP pins. This filter consists of a 20kΩ resistor between the DIFFSENS and DIFF_CAP pins, and a 0.1µF capacitor from DIFF_CAP to GND. See Figure 2 for the typical operating circuit. When ISO is connected to TPWR, the termination pins are isolated from the SCSI bus and V REF becomes inactive, and the device is in a low-power state. During thermal shutdown, the termination pins are isolated from the SCSI bus and VREF becomes high impedance. The DIFFSENS driver is shut down during either of these two events. LVD and SE signals indicate whether the SCSI bus segment is in LVD or SE mode. Chip Information TRANSISTOR COUNT: 8114 CMOS and 87 Bipolar PROCESS: BiCMOS SUBSTRATE CONNECTED TO GROUND Thermal Information Thermal Resistance (junction-to-ambient): θJA = +29°C/W Thermal Resistance (junction-to-case): θJC = +10°C/W _____________________________________________________________________ 5 DS2127 Ultra3 LVD/SE SCSI 14-Line Terminator Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.