SAB80C517 Datasheet, PDF (24/61 Pages) Siemens Semiconductor Group – 8-Bit CMOS Single-Chip Microcontroller

SAB 80C517/80C537
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 µs 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_IntAREF and V_IntAGND for the A/D converter are both programmable to one
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
DAPR (.3-.0)
DAPR (.7-.4)
0
0000
1
0001
2
0010
3
0011
4
0100
5
0101
6
0110
7
0111
8
1000
9
1001
10
1010
11
1011
12
1100
13
1101
14
1110
15
1111
V_IntAGND
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
–
–
–
V_IntAREF
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
Semiconductor Group
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