DS21S07A Dallas Semiconductor, DS21S07A Datasheet
DS21S07A
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DS21S07A Summary of contents
Page 1
... PoWeR) line, enhanced high–level noise immunity, intrinsic TERMPWR decoupling, and very low quies- cent current consumption. The DS2109 contains an output port that can control the power down pin of addi- tional terminators (DS21S07A) for Wide SCSI applica- tions. 022698 1/10 DS2109 ...
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... When embedded on a host bus adapter or mother- board, the DS2109 can automatically sense the ter- mination status of the SCSI bus and attach or isolate its resistors as needed to maintain proper bus termination. External and internal active termination can be provided by the DS21S07A. SCSI EXTERNAL CABLE SCSI INTERNAL CABLES ...
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... DS2109 in a low power mode (the bus sensing circuitry always stays active). The PDO (Power Down Output) pin can be con- nected to the pin of a DS21S07A SCSI terminator for Wide SCSI configurations, Figure 8. BUS CURRENT ...
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... P Heat Sink Ground. Internally connected to the mounting pad. Should be either grounded or electronically isolated from other circuitry. 9 PDO O Power Down Output. Connect to DS21S07A for Wide SCSI applica- tions, see Figure 8. 14 TPWR P Termination Power. Connect to the SCSI TERMPWR line. Bypass with a 2.2 F capacitor, see Figures 4 and 6. ...
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BUS GROUND SENSING CIRCUIT Figure 3 PDI PDE BUS GROUND DETECT CONFIGURATION Figure 4 INTERNAL SCSI CONNECTOR 22 26 2.2 F DS2109 PDI TPWR DISABLE TERMPWR 38 GND 36 PDE V REF 4.7 F DS2109 022698 5/10 ...
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DS2109 BUS CURRENT SENSING The DS2109 has the capability to use current sensing to determine if the SCSI bus is over– or under–terminated. A series 1 ohm resistor between pads R14 and TCS is inserted into the SCSI bus (preferably ...
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BUS CURRENT SENSE CONFIGURATION Figure 6 INTERNAL SCSI CONNECTOR 26 TERMPWR DS2109 R1 TPWR 2.2 F R13 R15 V REF R18 TCS 4.7 F R14 GND BUS CURRENT SENSE TIMING DIAGRAM Figure 7 TCS COMPARATORS LATCH –RST ...
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... TERMPWR1 REF2 REF1 GND 8 9 TERMPWR2 DS21S07A 16–PIN SOIC (300 MIL) 4.7 F 022698 8/10 DS2109 ISOLATED I > 32 mA? FROM SCSI BUS? BUS No Isolated No Connected No Connected No Connected Yes Isolated Yes Isolated Yes Isolated Yes Isolated TERMINATION POWER LINE PDI 1 28 GND R18 R2 ...
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ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the ...
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DS2109 NOTES: 1. PDI, PDE, TCS 2. 4.00V < TERMPWR < 5.25V. 3. 0.0V < signal lines < 3.0V. 4. All signal lines = 0.0V. 5. All signal lines open. 6. Power down enabled. 7. Guaranteed by design; not production ...