The LIAM (LInear Amplifier Module) is a compact linear current-controlled power supply system with ±5A@±60V output ratings.
This system is designed in order to have true bipolar operation i.e. real zero-crossing that allows smooth transitions around the zero-current level. Low-noise and high-stability are the main characteristics of these bipolar modules in order to obtain maximum performances on the relatively-generated magnetic field in the accelerator facilities.
Input ratings of the power supply unit is three-phase 180-220V(AC)@50-60Hz, adaptable to either the Japanese or US mains distribution network. European version is available upon request.
Output current and output voltage values are displayed on a large monitor placed on the module front panel. LEDs, also placed on the module front panel, give indication of the module operational status.
Remote connectivity to LIAM 6005, as for all other CAENels instrumentation, is guaranteed by means of a standard RJ-45 Ethernet connection (TCP-IP) that allows easily controlling and monitoring of the functionalities for the power supply unit (current setting, output current reading and setting, temperature monitoring, etc.).
The digital communication solution with respect to external analog one gives the advantages of greatly improved noise immunity: the analog voltage control signals that can come from external DACs are subject to noise pick-up and this effect is greatly amplified when needing very precise output currents or output voltages.
A load energy protection/damping circuit is implemented in order to protect the power supply and the load from over-voltage conditions. This feature is necessary when having large current in large inductive loads.
A monitor output rated at ±10V for a ±5A output current is also present on the rear panel of the power supply on a BNC connector and it can be used for external monitoring purposes.
The cooling of the LIAM 6005, a critical task when using linear power supplies, is performed by fan forced-air convection with a front-to-rear direction.
Easiness of control of large installations is also one of the big advantages of Ethernet connectivity since everything can be handled from the control system directly to the modules.
Maintenance issues are also easier and faster to carry out with the fact that the firmware for all the modules can be upgraded remotely.
Accuracy of the output current is also a great advantage of using digital interface: the calibration of the output current is performed, using a digital third-order polynomial fit curve, directly on the module itself so that external DACs drifts or non-linearity are avoided/bypassed.
This LIAM 6005 power unit, rated at 300W output power, is based on the cascade of a linear three-phase AC/DC stage and a linear current-controlled output stage.
Auxiliary AC/DC and DC/DC power supplies are also linear in order to avoid any switching noise that could be generated by the device. Linear transformers are optimized to reduce magnetic flux leakage that could cause EMI (Electro-Magnetic Interference).
Control of the output current is made by a high-resolution and low-drift Digital-to-Analog converter (DAC) that sets a resolution of about 180µA on the module output current setpoint.
External configurable interlocks are also provided on the LIAM 6005 rear panel in order to have the power supply connected, if needed, to some external devices/safety circuitries. A status output is also available on the rear panel of the device: it allows the monitoring of the module output stage (enabled/disabled) by opening/closing a contact.