SAB80C517-16-N-T40/85 Siemens Semiconductor Group, SAB80C517-16-N-T40/85 Datasheet - Page 24

• Manufacturer Part Number: SAB80C517-16-N-T40/85
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: Siemens Semiconductor Group

A/D Converter
The SAB 80C517 contains an 8-bit A/D Converter with 12 multiplexed input channels which
uses the successive approximation method. It takes 7 machine cycles to sample an analog
signal (during this sample time the input signal should be held constant); the total conversion
time (including sample time) is 13 machine cycles (13 s at 12 MHz oscillator frequency).
Conversion can be programmed to be single or continuous; at the end of a conversion an
interrupt can be generated.
A unique feature is the capability of internal reference voltage programming. The internal
reference voltages V
of 16 steps with respect to the external reference voltages. This feature permits a conversion
with a smaller internal reference voltage range to gain a higher resolution. In addition, the
internal reference voltages can easily be adapted by software to the desired analog input
voltage range (see table 2).
Table 2
Adjustable Internal Reference Voltages
Step
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Semiconductor Group
IntAREF
DAPR (.3-.0)
DAPR (.7-.4)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
and V
IntAGND
for the A/D converter are both programmable to one
23
V
0.0
0.3125
0.625
0.9375
1.25
1.5625
1.875
2.1875
2.5
2.8125
3.125
3.4375
3.75
–
–
–
IntAGND
SAB 80C517/80C537
V
5.0
–
–
–
1.25
1.5625
1.875
2.1875
2.5
2.8125
3.125
3.4375
3.75
4.0625
4.375
4.68754
IntAREF