Electronic Components Datasheet Search |
|
DS2105 Datasheet(PDF) 2 Page - Dallas Semiconductor |
|
DS2105 Datasheet(HTML) 2 Page - Dallas Semiconductor |
2 / 7 page DS2105 022698 2/7 FUNCTIONAL DESCRIPTION The DS2105 consists of a bandgap reference, buffer amplifier, and nine termination resistors (Figure 1). The bandgap reference circuit produces a precise 2.55V level which is fed to a buffer amplifier. The buffer pro- duces a 2.85V level and is capable of sourcing at least 24 mA 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 200 mA, and VREF will move less than 60 mV. When all lines settle in the quies- cent state, the regulator will consume about 5 mA. When the DS2105 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 isolate the DS2105 from the signal lines and effectively remove it from the circuit. The power–down pin (PD) has an inter- nal 50K Ω pull–up resistor. To place the DS2105 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 TERMPWR line and both the VREF1 and VREF2 pins must be tied together externally. Each DS2105 requires a 4.7 µF capacitor connected between the VREF pins and ground. Figure 2 details a typical SCSI bus configu- ration. In an 8–bit wide SCSI bus arrangement (“A” Cable), two DS2105’s would be needed at each end of the SCSI cable in order to terminate the 18 active signal lines. In a 16–bit wide SCSI bus arrangement (“P” Cable), three DS2105’s would be needed at each end of the SCSI cable in order to terminate the 27 active signal lines. DS2105 BLOCK DIAGRAM Figure 1 GND TERMPWR1 TERMPWR2 PD POWER DOWN CIRCUITRY 50K ohm BANDGAP REFERENCE 110 ohms R1 R2 R3 R4 R5 R6 R7 R8 R9 VREF1 VREF2 110 ohms 110 ohms 110 ohms 110 ohms 110 ohms 110 ohms 110 ohms 110 ohms |
Similar Part No. - DS2105 |
|
Similar Description - DS2105 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |