As the speed of systems increases, and the relative size of systems decreases, temperature management becomes more important. This results in the need to develop effective, compact, and inexpensive methods of thermal management.
This need arises not only in high speed computer systems, but also in many applications, such as: industrial temperature control, portable electronics, telecom switching boxes, biomedical devices, battery chargers, motor control, and automotive applications.
For many applications, correcting the temperature change in a prompt and accurate manner is critical. For example, some industrial motor life-times decrease by half if the insulation temperature increases by 10°C.
Actel's Flash-based Fusion devices have been introduced to the market with advanced thermal management features. Each device contains a 12-bit SAR ADC, a large amount of embedded Flash memory, up to 10 output gate drivers, and temperature, current, and/or voltage monitor input channels. Fusion devices are capable of temperature monitoring with 0,25°C resolution, and allow threshold comparison, system status logging and system protection control.
Temperature management
Figure 1 shows the block diagram of a simple thermal management system implemented with an Actel Fusion device. Fusion devices can monitor up to 10 temperature channels with external diode-connected bipolar transistors, or resistive temperature detectors (RTD). Based on the user preset threshold values stored in the embedded Flash memory, Fusion FPGAs can control multiple cooling and/or heating devices to keep systems at their desired temperature operating levels. The Fusion devices offer up to 600 Ksps sampling rate and use an ADC with up to 12-bit resolution to convert these analog signals into digital values for processing in the Fusion FPGA fabric.
In addition to thermal monitoring, the Actel Fusion devices provide temperature control with dedicated gate-driver outputs that have selectable drive strengths. Users can implement a PWM soft IP core or any custom design to drive the gate driver outputs. By connecting these outputs to power MOSFETs or even connecting them directly to loads, users can build customisable control circuits to fit a wide range of thermal management applications.
Logging
Fusion can also create a data log of the thermal system using the embedded Flash memory. A data log can be used to record alerts and any other system-critical data. With this data, the user can decide whether or not to modify the system further by adjusting the threshold settings and changing the PWM duty cycles to achieve better system performance.
Each Fusion device also has an internal temperature diode to monitor its own junction temperature. Users can keep track of the Fusion junction temperature and include the data in the thermal management system logic.
Conclusion
Actel Fusion FPGAs enable system designers to implement tightly integrated, low cost and sophisticated temperature management systems on an FPGA. The
0,25°C Fusion resolution, multiple temperature channel inputs, 12-bit configurable ADC, large Flash memory for data logging, and power MOSFETs to drive a load make it an ideal part for achieving high sampling accuracy with fast response times for many temperature control applications.
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