SAB80515 Datasheet, PDF (72/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

On-Chip Peripheral Components
7.4 A/D Converter
The SAB 80(C)515 provides an A/D converter with the following features:
– Eight multiplexed input channels
– The possibility of using the analog input channels (port 6) as digital inputs (ACMOS version
only).
– Programmable internal reference voltages (16 steps each) via resistor array
– 8-bit resolution within the selected reference voltage range
– 13 machine cycles conversion time for ACMOS versions (including sample time)
– 15 machine cycles conversion time for MYMOS versions (including sample time)
– Internal start-of-conversion trigger
– Interrupt request generation after each conversion
For the conversion, the method of successive approximation via capacitor array is used. The
externally applied reference voltage range has to be held on a fixed value within the specifications
(see section "A/D Converter Characteristics" in the data sheet). The internal reference voltages can
be varied to reduce the reference voltage range of the A/D converter and thus to achieve a higher
resolution.
Figure 7-25 shows a block diagram of the A/D converter. There are three user-accessible special
function registers:
ADCON (A/D converter control register), ADDAT (A/D converter data register) and DAPR (D/A
converter program register) for the programmable reference voltages.
Semiconductor Group
72