Actel Fusion Mixed-Signal FPGAs for the MicroBlade AdvancedMC Solution
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.
Two channels of the 32-channel ADCMUX are dedicated. Channel 0 is connected internally to V
CC
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
for details).
With Fusion, Actel also introduces the Analog Quad I/O structure (Figure
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.
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
Pr e li m i n a ry v0 . 4
1-5
ACTEL [ Actel Corporation ]
