AN8612NSR Datasheet, PDF (5/5 Pages) Panasonic Semiconductor – SCSI Active Terminator IC

s Precautions on Input Capacitance
The Interface Terminal Input Capacitance MAX25pF Stand-
ard are added from the SCSI II. This is because large stamp
input capacitance may prevent the normal signal transmission.
The capacitance value which does not cause the transmission
error differs, depending on the connection conditions of SCSI
equipment (such as distance between equipment, number of
equipment units and cable impedance), so, its proper value for
the AN8612NSR can not be identified. However, when the
input capacitance value specified in SCSII Standard,
MAX25pF is used, transmission error due to input capacitance
can hardly occur.
The input capacitance value is determined by the sum of the
following capacitances : active terminator (ex. 4.5 pF), printed
board (ex. 10 pF), driver receiver incorporated SCSI controller
(ex. 10 pF) and connector (ex. 0.5 pF).
[Evaluation Printed Board]
Therefore, particular care should be taken to each device for
input capacitance.
For example, on the evaluation printed board of the
AN8612NSR, the measured capacitance value per signal line
is approx. 2.2 pF and that per unit area is 0.13 pF/mm².
The thickness of printed board is 1 mm and the dielectric
constant of glass epoxy is 3.8 to 5.
For printed board, since the capacitance value differs,
depending on the thickness between layers and wiring length,
it should be measured actually. Also, it should be measured by
using the capacitance meter which can measure the capaci-
tance value of semiconductor.
Front
s Application Circuit
SCSI equipment (PC interface board)
SCSI equipment (MO)
Back
SCSI equipment (CD-ROM)
SGLINE1
SGLINE18
AN8612NSR
VCC
REGOUT
STANBAY
GND
SGLINE1
SGLINE18
AN8612NSR
VCC
REGOUT
STANBAY
GND
SGLINE1
SGLINE18
AN8612NSR
VCC
REGOUT
STANBAY
GND