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ST21S07A
SCSI TERMINATOR
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FULLY COMPLIANT WITH SCSI, SCSI-2 AND EMERGING SCSI-E STANDARDS PROVIDES ACTIVE TERMINATION FOR NINE SIGNAL LINES LOW DROPOUT (0.5V) VREGS:2.85V FACTORY TRIMMED TERMINATION 110 (2%) POWER DOWN MODE ISOLATES TERMINATION RESISTORS FROM THE BUS FULLY SUPPORTS ACTIVELY NEGATED SCSI SIGNALS COMPATIBLE TO THE DS2107, DS2107A AND DS21S07 ONBOARD THERMAL SHUTDOWN CIRCUITRY AVAILABLE IN SO-16L AND TSSOP20 SCSI BUS HOT PLUG-COMPATIBLE
SOP
TSSOP
DESCRIPTION The SCSI-2 and SCSI-3 standards recommend the use of active terminations at both ends of every cable segment in a SCSI system with a single-ended drivers and reveivers. The ST21S07A SCSI terminator, which is fully ORDERING CODES
Type ST21S07ACW ST21S07ACWR S21S07ACTR (*)
(*) Available on request
compliant with these standands, enables the designer to gain the benefits of active termination: greater immunity to voltages drop on the TERMPWR (TERMination PoWeR) line, enhanced high level noise immunity, intrinsic TERMPWR decouplig, and very low quiescent current consumption. The ST21S07A integrates a regulator and nine precise switched 110 termination resistors into a monolithic IC. The ST21S07A can be electrically isolatesd from the SCSI bus without physical removal from the SCSI device.
Temperature Range 0 to 70 C 0 to 70 C 0 to 70 C
Package SO-16L (Tube) SO-16L (Tape & Reel) TSSOP20 (Tape & Reel)
Comments 49parts per tube / 25tube per box 1000 parts per reel 2500 parts per reel
February 2001
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ST21S07A
PIN CONFIGURATION
SO-16L TSSOP20
PIN DESCRIPTION
PlN N (TSSP20) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 10 11 12 13 14 2 3 4 5 6 PlN N (SO-16L) 1 SYMBOL NAME AND FUNCTION
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TERMPWR1 Termination Power 1: Should be connected to the SCSI TERMPWR line. Must be decoupled with either a 2.2F or 4.7F. See Fig. 2. HS-GND Heat Sink Ground: Internally connected to the mounting pad. Should be either grounded or electrically isolated from the other circuitry. R1 Signal Termination 1: 110 Termination R2 Signal Termination 2: 110 Termination R3 Signal Termination 3: 110 Termination R4 Signal Termination 4: 110 Termination R5 Signal Termination 5: 110 Termination HS-GND Heat Sink Ground: Internally connected to the mounting pad. Should be either grounded or electrically isolated from the other circuitry. Reference Voltage 1: Must be external connected directly to the VREF2 VREF1 pin. Must be decoupoled with 4.7F capacitor as shown in Figure 2 GND Ground: Signal groud: 0V TERMPWR Termination Power21: Should be connected to the SCSI TERMPWR line. Must be decoupled with either a 2.2F or 4.7F. See Fig. 2. HS-GND Heat Sink Ground: Internally connected to the mounting pad. Should be either grounded or electrically isolated from the other circuitry. R6 Signal Termination 6: 110 Termination R7 Signal Termination 7: 110 Termination R8 Signal Termination 8: 110 Termination R9 Signal Termination 9: 110 Termination NC Not connected: Do not connect any signal to this pin HS-GND Heat Sink Ground: Internally connected to the mounting pad. Should be either grounded or electrically isolated from the other circuitry. Reference Voltage 2: Must be external connected directly to the VREF1 VREF2 pin. Must be decoupoled with 4.7F capacitor PD Power Down: When tied low, the ST21S07A enters a power down mode. Contains an internal 60K pull-up. Strap low to deactivate the ST21S07A, leave open circuited to activate the ST21S07A
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ST21S07A
ABSOLUTE MAXIMUM RATINGS
Symbol VPIN Tstg Top Parameter Voltage on Any Pin Relative to Ground Storage Temperature Range Operating Junction Temperature Range Value -1 to 7 -55 to +150 0 to +70 Unit V C C
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied.
RECOMMENDED OPERATING CONDITIONS
Symbol VTP VPDA VPDI Parameter TERMPWR Voltage PD Active PD Inactive Test Conditions Min. 4 -0.3 2 Typ. Max. 5.5 0.8 VTP+0.3 Unit V V V
DC CHARACTERISTICS (T A = 0 to 70C, unless otherwise specified.)
Symbol ITP IPD RTERM TSD CPD HPD IIH IIL Parameter TERMPWR Current Power Down Current Termination Resistance Die Thermal Shutdown Power Down TermniatioN Capacitance Power Down Hysteresis Input Leackage High Input Leackage Low Test Conditions (note 1, 3) (note 1, 4) (note 1, 2, 5) (note 1, 2) (note 1, 6) (note 1, 2, 5, 6) (note 1) (note 1, 8) (note 1, 7) -1 1 108 150 Min. Typ. 1.5 70 110 170 3 280 5 Max. 250 8 150 112 Unit mA mA A C pF mV A A
REGULATOR CHARACTERISTICS (TA = 0 to 70C, unless otherwise specified.)
Symbol VREF vDROP LIREG ILIM ISINK IOUT Parameter Output Voltage Drop-out Voltage Line Regulation Current Limit Sink Current Output Current (note 1, 2) (note 3, 6) (note 1, 4) (note 1, 2) (note 1) (note 1) (note9) 200 25.2 Test Conditions Min. 2.79 Typ. 2.85 0.3 0.25 0.5 450 Max. 2.93 0.75 2 3 Unit V V % % mA mA mA
LOREG Load Regulatio
Note 1: TERMPWR = 4V to 5.5V Note2: Signal Lines = 0V to TERMPWR Note3: All signal lines = 0V Note 4: All signal lines open Note 5: PD = 0V Note 6: Guaranteed by design; not production tested Note 7: R1 through R9 only Note 8: R1 through R9 and PD Note 9: VSIGNAL = 0.2V
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ST21S07A
FUNCTIONAL DESCRIPTION The ST21S07A consists of a bandgap reference, buffer amplifier, and nine termination resistors Figure 1). The bandgap reference circuit produces a precise 1.25V level which is fed to a buffer amplifier. The buffer produce a 2.85V level and is capable of sourcing at least 24mA into each of the termination resistors when the signal line is low (active). When the driver for a given signal line turns off, the terminator will pull the signal line to 2.85V (quiescent state). To handle actively negated SCSI signals, the buffer can sink 200mA. When all lines settle in the quiescent state, the regulator will consume about 1.5mA. When the ST21S07A is put into power-down mode by bringing PD low, the power-down circuitry will turn off the transistors on each signal line. This will isolated the ST21S07A from the signal lines and effectively remove it from the circuit. The Figure 1 : Block Diagram power-down pin (PD) has an internal pull-up resistor.To place the ST21S07A into an active state, the PD pin should be left open circuited. To ensure proper operation, both the TERMPWR1 and TERMPWR2 pins must be connected to the SCSI bus TREMPWR line and both the VREF1 and VREF2 pins must be tied together externally. Each ST21S07A requires a 4.7F capacitor connected between the VREF pins and ground. Figure 2 details a typical SCSI bus configuration. In an 8-bit wide SCSI bus arrangement ("A" Cable), two ST21S07A's would be needed at each end of the SCSI cable in order to terminate the 18 active signal lines. In a 16-bit SCSI bus arrangement ("P" Cable), three ST21S07A's would be need at each end of the SCSI cable in order to terminate the 27 active signal lines.
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ST21S07A
Figure 2 : Typical Scsi Bus Configuraion
NOTES: 1) C1 = 4.7F tantalium C2 = 2.2F tantalium or 4.7mF aluminum 2) If the ST21S07A is to be embedded into a peripheral that will act as a target on a SCSI bus, it is that recommended TERMPWR be derived from the SCSI cable, not generated locally. In this configuration, if a power failure occurs in the peripheral, it will not affect the bus. 3) A high frequency bypass capacitor (0.1F recommended) can be added in parallel to C1 for applications using fast rise/fall time drivers.
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ST21S07A
SO16L MECHANICAL DATA
DIM. MIN. A a1 a2 b b1 C c1 D E e e3 F L M S 7.4 0.5 10.1 10.0 1.27 8.89 7.6 1.27 0.75 8 (max.) 0.291 0.020 10.5 10.65 0.35 0.23 0.5 45 (typ.) 0.397 0.3.93 0.050 0.350 0.300 0.050 0.029 0.413 0.419 0.1 mm TYP. MAX. 2.65 0.2 2.45 0.49 0.32 0.014 0.009 0.020 0.004 MIN. inch TYP. MAX. 0.104 0.008 0.096 0.019 0.012
P013I
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ST21S07A
TSSOP20 MECHANICAL DATA
mm MIN. A A1 A2 b c D E E1 e K L 0o 0.50 0.05 0.85 0.19 0.09 6.4 6.25 4.3 6.5 6.4 4.4 0.65 BSC 4o 0.60 8o 0.70 0o 0.020 0.10 0.9 TYP. MAX. 1.1 0.15 0.95 0.30 0.2 6.6 6.5 4.48 0.002 0.335 0.0075 0.0035 0.252 0.246 0.169 0.256 0.252 0.173 0.0256 BSC 4o 0.024 8o 0.028 0.004 0.354 MIN. inch TYP. MAX. 0.433 0.006 0.374 0.0118 0.0079 0.260 0.256 0.176
DIM.
A
A2 A1 b e K c L E
D
E1
PIN 1 IDENTIFICATION
1
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Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. (c) The ST logo is a registered trademark of STMicroelectronics (c) 2001 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom (c) http://www.st.com
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