|All IMP multimode
devices feature auto-selectable LVD or SE (single-ended) termination,
high-speed response without external capacitors and a high bandwidth
driver that reduces channel-to-channel noise and crosstalk.
are minimized. In the LVD mode, a fast buffer instead of regulators
that require external capacitors supplies the common mode voltage.
In SE mode, the nonlinear adaptive terminator eliminates external
capacitors and more closely matches the loaded SCSI bus impedance.
No external capacitors are required for references or regulators
on the IMP multimode devices. Only a termpower bypass capacitor
In addition, other
IC terminators require an external RC delay network to accommodate
the100mS delay it takes between changes on the DIFFSENSE line
and changes on their outputs. The IMP multimode parts include
an internal digital counter that eliminates the external RC network.
Driving the Master/Slave
pin LOW disables the on-board DIFFSENS reference, allowing the
use of an external master reference. If the Master/Slave pin is
allowed to float or is driven HIGH, the internal DIFFSENSE reference
Proper mode selection
is automatic. If DIFFSENSE is below 0.5V single-ended operation
is selected and if between 0.7V and 1.9V LVD operation is selected.
Outputs are placed in a high-impedance state when DIFFSENSE is
A sleep or disable
mode reduces supply current to 10 microamperes maximum and puts
the DIFFSENSE and outputs in a high impedance state.