Actel Fusion Mixed-Signal FPGAs for the MicroBlade AdvancedMC Solution

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Unprecedented Integration

Integrated Analog Blocks and Analog I/Os

Fusion devices offer robust and flexible analog mixed-signal capability in addition to the high-

performance flash FPGA fabric and flash memory block. The many built-in analog peripherals

include a configurable 32:1 input analog MUX, up to 10 independent MOSFET gate driver outputs,

and a configurable ADC. The ADC supports 8-, 10-, and 12-bit modes of operation with a

cumulative sample rate up to 600 k samples per second (ksps), differential nonlinearity (DNL) < 1.0

LSB, and Total Unadjusted Error (TUE) of 0.72 LSB in 10-bit mode. The TUE is used for

characterization of the conversion error and includes errors from all sources, such as offset and

linearity. Internal bandgap circuitry offers 1% voltage reference accuracy with the flexibility of

utilizing an external reference voltage. The ADC channel sampling sequence and sampling rate are

programmable and implemented in the FPGA logic using Designer and Libero IDE software tool

support.

and can be used to monitor core power supply. Channel 31 is connected to an internal temperature

diode which can be used to monitor device temperature. The 30 remaining channels can be

connected to external analog signals. The exact number of I/Os available for external connection

signals is device-dependent (refer to the "MicroBlade Fusion Solutions" table on page I for details).

With Fusion, Actel also introduces the Analog Quad I/O structure (Figure 1-1 on page 1-6). Each

quad consists of three analog inputs and one gate driver. Each quad can be configured in various

built-in circuit combinations, such as three prescaler circuits, three digital input circuits, a current

monitor circuit, or a temperature monitor circuit. Each prescaler has multiple scaling factors

programmed by FPGA signals to support a large range of analog inputs with positive or negative

polarity. When the current monitor circuit is selected, two adjacent analog inputs measure the

voltage drop across a small external sense resistor. Built-in operational amplifiers amplify small

voltage signals (2 mV sensitivity) for accurate current measurement. One analog input in each quad

can be connected to an external temperature monitor diode and achieves detection accuracy of

±3ºC. In addition to the external temperature monitor diode(s), a Fusion device can monitor an

internal temperature diode using dedicated channel 31 of the ADCMUX.

Figure 1-1 on page 1-6 illustrates a typical use of the Analog Quad I/O structure. The Analog Quad

shown is configured to monitor and control an external power supply. The AV pad measures the

source of the power supply. The AC pad measures the voltage drop across an external sense resistor