The Low-Pressure Pump Main Board (Lpm) - Agilent Technologies 1200 Series Reference Manual

Introduction to the Quaternary Pump 7

The Low-Pressure Pump Main Board (LPM)

The board controls all information and activities of all assemblies within the
quaternary pump. The operator enters parameters, changes modes and
controls the quaternary pump through interfaces (CAN, GPIB or RS-232C)
connected to the user-interfaces. Figure 48 and Figure 49 show the block
diagrams of this board.
ASIC — Application-Specific Integrated Circuit
The application-specific integrated circuit (ASIC) includes all digital logic for
the core processor functions and also for module-specific functions.
Motor Drive
The drive comprises motor control, motor amplifier (drive) and current
control.
Active Inlet Valve Drive
The drive comprises two amplifiers for the two contacts of valve solenoid.
Gradient Valve Drive
The drive consists of the amplifiers for the four solenoids of the gradient valve.
Pressure Converter
This block comprises a filter and amplifier for the pressure-sensor-signal, a
multiplexer, an A/D converter and an offset correction for the analog pressure
output signal. The output voltage is 2 mV/bar.
Leak Converter
This block comprises a PTC for the leak identification and a NTC for the
ambient temperature measurement. This assures that temperature changes
are not identified as leak. A leak would cool down the PTC and its change in
resistance results in a leak signal.
1200 Series QP Reference Manual 215