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U101 controls the relays on the module using an 8-bit data bus and
three control lines. The data lines are latched and applied to the
relay drivers.
U101 enters a low-power idle mode when inactive. U101 responds
when a command is received or when a scheduled reference junction
temperature measurement is taken.
The relays use a bu5 Volt power supply. U101 supplies two
drive enable lines (DR_EN and +5NL_EN) that connect Vcc from the
digital bus with the relay drive lines through Q101 (+5R or +5NL).
To minimize the current through DGND caused by static discharge,
the ground return (ZGND) is isolated from the backplane ground
through a bead L102.
Relay Drivers
Two types of single-coil relays are used on the switch modules:
latching
and
non-latching
. Typical driver configurations are shown below.
Chapter 5 Theory of Operation
Switch Modules
140
Summary of Contents for 34970A
Page 1: ...Agilent 34970A Data Acquisition Switch Unit Service Guide ...
Page 34: ...32 ...
Page 35: ...2 Quick Start 2 ...
Page 49: ...3 Front Panel Overview 3 ...
Page 62: ...60 ...
Page 63: ...4 Calibration Procedures 4 ...
Page 118: ...116 ...
Page 119: ...5 Theory of Operation 5 ...
Page 159: ...6 Service 6 ...
Page 177: ...General Disassembly 4 3 2 1 6 Chapter 6 Service Disassembly 175 ...
Page 178: ...Internal DMM Disassembly 3 2 1 Chapter 6 Service Disassembly 176 ...
Page 180: ...Additional Chassis Disassembly 1 2 Chapter 6 Service Disassembly 178 ...
Page 181: ...Plug In Module Disassembly Needle nose Pliers 6 Chapter 6 Service Disassembly 179 ...
Page 182: ...180 ...
Page 183: ...7 Replaceable Parts 7 ...
Page 220: ...Chapter 7 Replaceable Parts Manufacturer s List 218 ...
Page 221: ...8 Schematics 8 ...
Page 272: ......