4501 datasheet(49/212 Pages) RENESAS

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4501 Group

HARDWARE

Rev.2.01

Feb 07, 2005

REJ09B0192-0201

FUNCTION BLOCK OPERATIONS

(15) Definition of A/D converter accuracy

The A/D conversion accuracy is defined below (refer to Figure 32).

• Relative accuracy

➀ Zero transition voltage (V0T)

This means an analog input voltage when the actual A/D con-

version output data changes from “0” to “1.”

➁ Full-scale transition voltage (VFST)

This means an analog input voltage when the actual A/D con-

version output data changes from “1023” to ”1022.”

➂ Linearity error

This means a deviation from the line between V0T and VFST of

a converted value between V0T and VFST.

➃ Differential non-linearity error

This means a deviation from the input potential difference re-

quired to change a converter value between V0T and VFST by 1

LSB at the relative accuracy.

• Absolute accuracy

This means a deviation from the ideal characteristics between 0

to VDD of actual A/D conversion characteristics.

Fig. 32 Definition of A/D conversion accuracy

VFST–V0T

1022

VDD

1024

Vn: Analog input voltage when the output data changes from “n” to

“n+1” (n = 0 to 1022)

• 1LSB at relative accuracy

→

(V)

• 1LSB at absolute accuracy

→

(V)

VDD

V1022

Vn+1

n+1

1022

1023

Output data

Differential non-linearity error =

Linearity error =

[LSB]

b–a

[LSB]

Actual A/D conversion

characteristics

a: 1LSB by relative accuracy

b: Vn+1–Vn

c: Difference between ideal Vn

and actual Vn

Zero transition voltage (V0T)

Analog voltage

Full-scale transition voltage (VFST)

Ideal line of A/D conversion

between V0–V1022

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