Hitachi HUS157336EL3600 Oem Manual page 19

5.2 Low voltage differential (LVD) mode
The NW and NC drives have two different transceivers to allow customer to use it in
traditional systems which may use single-ended drivers and receivers, or to use it in
low voltage differential (LVD) systems which use LVD drivers and receivers.
Their I/O circuits are selectable using the I/O "DIFFSENS" line. When the I/O
"DIFFSENS" line is between -0.35V and +0.5V, the drive interface circuits operate
single-ended. When "DIFFSENS" is between +0.7V and +1.9V, the drive interface
circuits operate LVD.
Customer can configure the drive to switch between single-ended and LVD modes
using the I/O "DIFFSENS" line, or force it to operate in single-ended mode only as
described later in this document.
Note 1: To operate at LVD mode, all devices on the same bus must be running in LVD
mode. If you add any single-ended device to a bus that is operating in LVD mode,
all devices drop back to operating in single-ended mode. This eliminates the
possibility of reaching Ultra-2 SCSI transfer rates.
Note 2: Do not mix LVD drives on the same daisy chain with devices having high voltage
differential (HVD) interface circuits.
Drawing No. Sheet No. Revision 5
K6602906 19/46 2003/6/12