Specifications
The previous figure shows
some key aspects of the
34945A/L4445A Switch Driver:
• Each 34945A/L4445A module
can supply 24 V to the first
34945EXT
• Daisy chained 34945EXT’s
must use an external
power supply
• Each 34945EXT can only
support one voltage type
(24 V, 12 V, or 5 V)
• A total of eight (8)
34945EXT’s can be present in
a single 34980A mainframe or
connected to an L4445A Module
• The 34945EXT’s can be daisy
chained or directly connected
to 34945A/L4445A modules
There are five distribution
boards (Y1150A through
Y1154A)
for directly driving
Agilent’s most popular switches
using common ribbon cables
and socket headers/connectors.
The sixth distribution board,
the Y1155A, is designed to
drive virtually any switch or
attenuator. Instead of providing
socket headers to the switches,
the Y1155A provides screw
terminals to connect to relay
coils and position indicators.
As seen in the diagram below,
up to four (4) distribution boards
can be mounted onto a single
34945EXT. The Y115x distribu-
tion boards are passive; they
only provide various socket
headers or screw terminals
that interface external devices
to the 34945EXT.
The 34945EXT distribution
boards provide position feed-
back and can directly drive
LED’s to be used to describe
signal paths on a test system
panel. It is particularly useful
for test system operators to
have a visual representation
of the signal path.
The 34945EXT module is
essentially a multifunction
module:
• Digital outputs to drive
relay coils (programmable
pulse or continuous)
• Digital inputs to read
position of switch contacts
• Digital outputs to drive LED’s
used for position indication
• Power distribution and
current limitation (no fuses)
Each Y115x distribution board
can drive up to 16 coils. The
distribution boards can drive
coils continuously or with
programmable-width pulses.
Continuous drive switches
typically require a significant
amount of current to energize
a coil (100 mA to 300 mA each
for 24 V coils, and much higher
for 12 V and 5 V). Continuous
drive switches usually have a
single coil that closes a normally
open switch. The switch is closed
for as long as power is applied.
6
External
power
supply
Connect to
next EXT
RJ-45
To 34945A
9-pin D-sub
Y115x distribution boards