AFS090 datasheet(111/334 Pages) MICROSEMI

111 / 334 page

Fusion Family of Mixed Signal FPGAs

R e visio n 2

2 - 95

Fusion uses a remote diode as a temperature sensor. The Fusion Temperature Monitor uses a

differential input; the AT pin and ATRTN (AT Return) pin are the differential inputs to the Temperature

Monitor. There is one Temperature Monitor in each Quad. A simplified block diagram is shown in

Figure 2-75.

The Fusion approach to measuring temperature is forcing two different currents through the diode with a

ratio of 10:1. The switch that controls the different currents is controlled by the Temperature Monitor

Strobe signal, TMSTB. Setting TMSTB to '1' will initiate a Temperature reading. The TMSTB should

remain '1' until the ADC finishes sampling the voltage from the Temperature Monitor. The minimum

sample time for the Temperature Monitor cannot be less than the minimum strobe high time minus the

setup time. Figure 2-76 shows the timing diagram.

Note: When the IEEE 1149.1 Boundary Scan EXTEST instruction is executed, the AG pad drive

strength ceases and becomes a 1 µA sink into the Fusion device.

Figure 2-75 • Block Diagram for Temperature Monitor Circuit

Figure 2-76 • Timing Diagram for the Temperature Monitor Strobe Signal

TMSTBx

VDD33A

ATRTNxy

ATx

12.5 X

∆V

to Analog MUX

(refer Table 2-36

for MUX Channel

Number)

VADC

100 μA

10 μA

–

VADC

TMSTBx

ADC should start

sampling at this point

ADCSTART

tTMSLO

tTMSHI

tTMSSET

AFS090 Datasheet(PDF) 111 Page - Microsemi Corporation