Analog-to-Digital Converter - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 595

Analog
comparator

+ V IN (analog input)

-

V RH

Successive-
approximation
register (SAR)

Control
logic

Digital-to-analog
converter

Clock

V RL

Output
latch

Digital
code

Figure 12.4 ■ Block diagram of a successive-approximation A/D converter

Start

SAR[n - 1, . . . , 0] ← 0

i ← n - 1

SAR[i] ← 1

Convert the value in
SAR to a voltage

← i - 1

Is the
converted voltage
greater than
the input?

Yes

SAR[i] ← 0

No

No

i = 0?

Yes

Stop

Figure 12.5 ■ Successive-approximation A/D conversion method