Circuit Note

CN-0267

Rev. A | Page 7 of 8

The performance summary can be seen in Table 3, and the

signal plots are shown in Figure 8 and Figure 9.

Table 3. Primary Sensor Input Noise and Resolution

Parameter

Pressure

Sensor

Resistive

Network

Full Scale

207 kPa

246 kPa

Noise RMS

1.3 Pa

0.68 Pa

Peak-to-Peak Noise

6.8 Pa

3.6 Pa

Resolution Effective (rms)

17.2 bit

18.5 bit

Noise-Free Resolution (p-p)

14.9 bit

16.1 bit

Figure 8. Pressure Sensor Input Signal Plot

Figure 9. Resistive Network as Primary Input Signal Plot

Secondary Sensor Input Performance

Similar to the primary sensor, the performance of the secondary

sensor input is mainly determined by the analog front-end of

the ADuCM360 with the exception of noise performance.

The analog input was configured to transmit temperature in

degrees Celsius (°C) to a master over the HART communication

path. Analysis was performed on two tests of 100 samples to

quantify the performance.

The first test was performed using the platinum 100 Ω sensor

on the board, and the second test was performed with the sensor

replaced on the board by a standard (fixed) 100 Ω ± 1% resistor.

The performance summary is shown in Table 4, and the signal

plots are shown in Figure 10 and Figure 11.

Table 4. Secondary Sensor Input Noise Performance

Parameter

Pressure Sensor

Resistive Network

Noise RMS

0.037°C

0.033°C

Noise Peak to Peak

0.19°C

0.16°C

Figure 10. RTD (Platinum 100 Ω) Sensor Input Signal Plot

Figure 11. Fixed 100 Ω ± 1% Resistor as the Secondary Input Signal Plot

20

25

30

35

40

0

10

20

30

40

50

60

70

80

90

100

SAMPLE

–10

–5

0

5

10

0

10

20

30

40

50

60

70

80

90

100

SAMPLE

23.0

23.5

24.0

24.5

25.0

0

10

20

30

40

50

60

70

80

90

100

SAMPLE

–1.0

–0.5

0.0

0.5

1.0

0

10

20

30

40

50

60

70

80

90

100

SAMPLE