AFS090 datasheet(123/334 Pages) MICROSEMI

123 / 334 page

Fusion Family of Mixed Signal FPGAs

R e visio n 2

2 - 107

ADC Input Multiplexer

At the input to the Fusion ADC is a 32:1 multiplexer. Of the 32 input channels, up to 30 are user

definable. Two of these channels are hardwired internally. Channel 31 connects to an internal

temperature diode so the temperature of the Fusion device itself can be monitored. Channel 0 is wired to

the FPGA’s 1.5 V VCC supply, enabling the Fusion device to monitor its own power supply. Doing this

internally makes it unnecessary to use an analog I/O to support these functions. The balance of the MUX

inputs are connected to Analog Quads (see the "Analog Quad" section on page 2-82). Table 2-40 defines

which Analog Quad inputs are associated with which specific analog MUX channels. The number of

Analog Quads present is device-dependent; refer to the family list in the "Fusion Family" table on page I

of this datasheet for the number of quads per device. Regardless of the number of quads populated in a

device, the internal connections to both VCC and the internal temperature diode remain on Channels 0

and 31, respectively. To sample the internal temperature monitor, it must be strobed (similar to the AT

pads). The TMSTBINT pin on the Analog Block macro is the control for strobing the internal temperature

measurement diode.

To determine which channel is selected for conversion, there is a five-pin interface on the Analog Block,

CHNUMBER[4:0], defined in Table 2-39.

Table 2-40 shows the correlation between the analog MUX input channels and the analog input pins.

Table 2-39 • Channel Selection

Channel Number

CHNUMBER[4:0]

00000

00001

00010

00011

11110

11111

Table 2-40 • Analog MUX Channels

Analog MUX Channel

Signal

Analog Quad Number

Vcc_analog

AV0

Analog Quad 0

2AC0

3AT0

AV1

Analog Quad 1

5AC1

6AT1

AV2

Analog Quad 2

8AC2

9AT2

AV3

Analog Quad 3

AC3

AT3

AV4

Analog Quad 4

AC4

AT4

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