CS5566

22

DS806PP2

5/4/09

Figure 16 illustrates the device with a small signal 1/1,000,000 of full scale. The signal input for Figure 16

is about 8.2 microvolts peak to peak, or about 17 codes peak to peak. Figure 17 illustrates the converter

with a signal at about 2.6 microvolts peak to peak, or about 5 codes peak to peak. The CS5566 achieves

superb performance with this small signal.

Figure 18 illustrates the noise floor of the converter from 0.1 Hz to 2.5 kHz. The plot is entirely free of spu-

rious frequency content due to digital activity inside the chip.

Figure 19 illustrates a noise histogram of the converter constructed from 4096 samples.

-180

-160

-140

-120

-100

-80

-60

-40

-20

0

0

500

1k

1.5k

2k

2.5k

Frequency (Hz)

277 Hz, -130 dB

32k Samples @ 5 kSps

0

10

20

30

40

50

60

70

80

90

100

4096 Samples

Mean = 96.32

Std. Dev. = 21.3

Max - Min = 150

Output Codes

-180

-160

-140

-120

-100

-80

-60

0.1

1

10

100

1k

2.5k

Frequency (Hz)

Shorted Input

2M Samples @ 5 kSps

16 Averages

Figure 17. Spectral Performance, -130 dB

Figure 19. Noise Histogram (4096 Samples)

Figure 18. Spectral Plot of Noise with Shorted Input