Table 16. TAP Setting of the Comb Digital Filter and the First Zero Frequency [FS=83.3 kHz]

COMB1（TPS1）

COMB2（TPS2）

TPSX<1:0>

TAP（N） First Zero Frequency（Hz） Tap（N） First Zero Frequency（Hz）

11

16384

5

256

325

10

8192

10

128

650

01

4096

20

64

1300

00

2048

40

32

2600

Reading and Calculating of Digital-to-Analog Converter

Due to the manufacture process drift, there is an offset voltage in the FS501 ADC such that an offset

value is existed in the ADC output. In order to eliminate the offset value, FS501 provides three

operation modes, which can be set by CYS <1:0> of control register SETADC. The SUM1 output

and calculation are different in different operation modes, and they are described in the following

subsection.

8.4.1 ADC Output SUM1

Set CYS<1:0>=00, the ADC inputs are short circuited, and we can find the negative offset voltage of

the ADC from SUM1.

Set CYS<1:0>=11, as described by Equation 3 and we can find the equivalent voltage of the input

signal from SUM1.

Set CYS<1:0>=01, and the SUM1 output is the value of an ideal ADC. The transfer function is

Equation 1. This mode is suitable for high resolution measurement.

When CYS<1:0>01, the output rate of SUM1 is the first zero frequency,

1

Z

f

, of COMB1 as

described in Equation 6. When CYS<1:0> =01, the output rate equals

2

1

Z

f

.