Actel Fusion Mixed-Signal FPGAs
Table 2-37 • Recommended Resistor for Different Current Range Measurement
Current Range
> 5 mA – 10 mA
> 10 mA – 20 mA
> 20 mA – 50 mA
> 50 mA – 100 mA
> 100 mA – 200 mA
> 200 mA – 500 mA
> 500 mA – 1 A
> 1 A – 2 A
Recommended Minimum Resistor Value (Ohms)
10 – 20
5 – 10
2.5 – 5
1 – 2
0.5 – 1
0.3 – 0.5
0.1 – 0.2
0.05 – 0.1
0.025 – 0.05
0.0125 – 0.025
0.00625 – 0.02
> 2 A – 4 A
> 4 A – 8 A
> 8 A – 12 A
I
RSENSE
0 to
–10.5 V
AVx
ACx
CMSTBx
to Analog MUX
VADC
10 X
(refer Table 2-36
for MUX channel
number)
Current Monitor
Figure 2-73 • Negative Current Monitor
Terminology
Accuracy
The accuracy of Fusion Current Monitor is 2 mV minimum plus 5% of the differential voltage at
the input. The input accuracy can be translated to error at the ADC output by using EQ 2-4. The
10 V/V gain is the gain of the Current Monitor Circuit, as described in the "Current Monitor"
section on page 2-90. For 8-bit mode, N = 8, VAREF= 2.56 V, zero differential voltage between AV
and AC, the Error (EADC) is equal to 2 LSBs.
2N
VAREF
--------------
EADC = (2mV + 0.05 VAV – VAC ) × (10V) ⁄ V ×
EQ 2-4
where
N is the number of bits
VAREF is the Reference voltage
VAV is the voltage at AV pad
VAC is the voltage at AC pad
Preliminary v1.7
2-93
ACTEL [ Actel Corporation ]
