UCC5686, UCC5687

27-LINE 3V - 5V LVD TERMINATOR FOR WIDE ULTRA2, ULTRA3,

ULTRA160, AND ULTRA320 SCSI WITH INTEGRATED SPI3 DELAY

SLUS459B – OCTOBER 2000 – REVISED APRIL 2001

4

POST OFFICE BOX 655303

pin descriptions

STRMPWR: 2.7 V to 5.25 V power supply for all circuitry except the 1.25-V regulator.

SGND: Ground reference for all circuitry except the 1.25-V regulator.

PTRMPWR: 2.7 V to 5.25 V power supply for the 1.25-V regulator.

PGND: Ground reference for the 1.25-V regulator.

REG: Output of the internal 1.25-V regulator; must be connected to a 4.7-

µF bypass capacitor and a

high-frequency, low-ESR 0.01-

µF capacitor to GND.

DIFSENS: Drives the SCSI bus DIFF SENSE line to 1.3 V to detect what types of devices are tied to the bus.

DIFFB: DIFF SENSE input pin. Connect through a 20-k

Ω resistor to DIFSENS and through a 0.1-µF capacitor

to GND. Input to comparators that detect what type of drives are connected to the SCSI bus.

DISCNCT1: Disconnect one controls termination lines 10–27 (control and low byte).

DISCNCT2: Disconnect two controls termination lines 1–9 (high byte).

LVD: TTL compatible status bit indicating when low-voltage-differential voltage is present on DIFFB.

L1– thru L27–: Negative lines for the SCSI bus.

L1+ thru L27+: Positive lines for the SCSI bus.