FMC-Pico-1M4 User’s Manual
8
1.Introduction
This chapter describes the general characteristics and main features of FMC-
Pico-1M4 mezzanine cards.
1.1 FMC-Pico-1M4 Overview
The CAEN ELS FMC-Pico-1M4 is a standard FPGA Mezzanine Card (FMC)
Low Pin Count (LPC) daughter board that allows high resolution monitoring of
bipolar currents up to 1 mA (standard configuration) with maximum sampling rate of
1 MHz. It is mechanically and electrically compliant to the FMC standard
(ANSI/VITA 57.1).
The front-end is composed of a specially designed transimpedance input stage
for current sensing combined with analog signal conditioning and filtering stages
making use of state-of-the-art electronics. The 20-bit resolution is obtained from
independent, simultaneous sampling and low-delay SAR (Successive Approximation
Register) Analog to Digital Converters (ADCs).
Each channel has two full-scale measuring ranges, up to ±1 mA and ±1 µA
(customizable upon request) respectively and the current source can be floating up to
±300 V respect to the FMC ground. The floating capability of the inputs is perfectly
suitable for applications where the detector or current source needs to be biased.
The analog front end is designed in order to achieve low noise, low
temperature dependence and very small unbalance between channels. The analog
characteristics can be further improved by requesting a factory calibration of the
channels. Calibration data are stored in the on-board EEPROM memory that can be
read via an I2C bus on the FMC connector.
A metallic shield has a dual function of shielding the analog front end from
external noise sources and also galvanically isolates the internal electronics that could
be floating up to ±300 V.
A trigger signal can be fed to the FMC connector in order to start the
conversion of data samples: this feature allows synchronizing the board acquisition to
an external event - e.g. machining revolution frequency in storage rings.
Data readout is performed via separate SPI links - i.e. one for each channel,
sharing the same clock signal.
