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A-D CONVERTER

7733 Group User’s Manual

9–16

Analog input voltage (mV)

17.5

37.5

q8-bit A-D converter (When VREF = 5.12 V)

Output code

(A-D conversion result)

qM37733MHBXXXFP’s A-D converter with ideal characteristics (When VREF = 5.12 V)

Output code

(A-D conversion result)

8-bit

resolution

10-bit

resolution

(g)

Analog input voltage (mV)

8-bit resolution

10-bit resolution

g: Difference from output code change point

VREF: Reference voltage

(g)

9.4.3 Comparison voltage when resolution = 8 bits

When 8-bit resolution is selected in the M37733MHBXXXFP, the high-order 8 bits of the 10-bit successive

approximation register is the conversion result.

Accordingly, when compared with the 8-bit A-D converter, the comparison reference voltage is different by

3VREF/2048 (refer to the underlined portions in the Table 9.4.1). The difference of the output code change

point is generated as shown in Figure 9.4.3.

M37733MHBXXXFP (When resolution = 8 bits)

8-bit A-D converter

Comparison reference

voltage Vref

VREFV1/28 ! nV2 – VREF/210 ! 0.5

VREF/28 ! n – VREF/28 ! 0.5

VREFV1: Reference voltage

nV2: Contents of successive approximation register

Table 9.4.1 Compare reference voltage

9.4 Absolute accuracy and Differential non-linearity error

Fig. 9.4.3 Difference of output code change point

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