iC-NQL

13-bit Sin/D CONVERTER WITH SSI INTERFACE

Rev D2, Page 13/24

MAXIMUM POSSIBLE CONVERTER FREQUENCY

The converter frequency automatically adjusts to the

value necessary for the input frequency and resolution.

This value ranges from zero to a maximum dependent

on the oscillator frequency which can be set using reg-

ister FCTR.

Serial data output

For SSI output the maximum possible converter fre-

quency can be adjusted to suit the maximum input fre-

quency; an automatic converter resolution step-down

feature can be enabled via the FCTR register. Should

the input frequency exceed the frequency limit of the

selected converter resolution, the LSB is kept stable

and not resolved any further; the interpolation resolu-

tion halves.

If the next frequency limit is overshot, the LSB and the

LSB+1 are kept stable and so on. When the input fre-

quency again sinks below this frequency limit, the fine

resolution automatically returns.

Max. Possible Converter Frequency For Serial Data Output

Resolution

Protocol

Max. Input Frequency

Restrictions

Examples*

Requirements

at high input frequency

FCTR

Min. Res.

bin

dec SSI

8192

1024

200

0x0004

X

X

X

fosc()min / 40 / Resolution

–

0.16

1.27

6.5

0x4102

≥ 8

X

X

X

fosc()min / 24 / Resolution

Rel. angle error 2x increased

0.26

2.1

10.8

0x4202

≥ 16

X

X

X

2 x fosc()min / 24 / Res.

Rel. angle error 4x increased

0.53

4.2

21.6

0x4304

≥ 32

X

X

X

4 x fosc()min / 40 / Res.

Rel. angle error 8x increased

0.64

5.1

26.0

0x4602

≥ 64

X

-

X

4 x fosc()min / 24 / Res.

Resolution lowered by factor of 2

1.1

8.5

-

0x4A02

≥ 128

X

-

X

8 x fosc()min / 24 / Res.

Res. lowered by factor of 2-4

2.1

16.9

-

0x4E02

≥ 256

X

-

X

16 x fosc()min / 24 / Res.

Res. lowered by factor of 2-8

4.2

33.8

-

0x5202

≥ 512

X

-

X

32 x fosc()min / 24 / Res.

Res. lowered by factor of 2-16

8.5

67.7

-

0x5602

≥ 1024

X

-

X

64 x fosc()min / 24 / Res.

Res. lowered by factor of 2-32

16.9

135

-

0x5A02

≥ 2048

X

-

X

128 x fosc()min / 24 / Res.

Res. lowered by factor of 2-64

33.8

250

-

0x5E02

≥ 4096

X

-

X

256 x fosc()min / 24 / Res.

Res. lowered by factor of 2-128

67.7

-

-

0x6202

8192

X

-

X

512 x fosc()min / 24 / Res.

Res. lowered by factor of 2-256

135

-

-

Notes

*) Calculated with fosc()min taken from Electrical Characteristics item A01.

Table 14: Maximum converter frequency for serial data output.