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ADwin
In the bipolar setting you will get a zero offset, also called offset U
lowing text.
For the voltage range of −10V ... +10V applies:
= −10V
U
OFF
The ADwin-Gold has a programmable gain (PGA), with which you can amplify
the input voltage by the factors 1, 2, 4, and 8. At the same time the measure-
ment range gets smaller by the corresponding gain factor k (see Annex "Tech-
nical Data").
Please note that upon applications with k
amplified respectively.
The quantization level (U
ence and is equivalent to the voltage of the least significant bit (LSB). It is dif-
ferent for the two ADCs:
– 16-bit ADC: U
= 20V / 2
LSB
– 14-bit ADC: U
= 20V / 2
LSB
The measured 16-bit value of the ADC is returned in the lower word of the reg-
ister. A DAC value, which is to be output, has to be available there.
Bit No.
31...16
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
0
32-bit-
memory
0
Fig. 9 – Storage of the ADC/DAC bits in the memory
In order to compare the measurement values of the 14-bit ADC with the values
of the 16-bit ADC, the converted value is written left-aligned into the lower word
of the register at the 14-bit ADC. Therefore the lower 2 bits are always 0 (zero).
The 16384 digits of the 14-bit ADC are mapped to the 65536 digits of the 16-
bit ADC. Thus 4 digits of the 16-bit ADC are equivalent to one digit of the 14-
bit ADC.
Therefore the following equations can be used for both ADC types:
Conversion Digit
Voltage
For a DAC:
U OUT
For an ADC (14-bit and 16-bit):
U IN
ADwin-Gold USB / ENET, manual version 3.8, October 2005
>1 the interference signals are
V
) is the smallest digitally displayable voltage differ-
LSB
16
= 305.175µV
14
= 1220.7µV
16-bit value of the 16-bit ADC / DAC in the lower word
14-bit value of the 14-bit ADC in the lower word
⋅
Digits U LSB
=
+
U OUT U OFF
–
Digits
=
-------------------------------------------- -
U LSB
⋅
k v U IN
U OFF
–
Digits
=
--------------------------------------------------- -
U LSB
⋅
Digits U LSB U OFF
+
=
-------------------------------------------------- -
k v
in the fol-
OFF
U OFF
Inputs and Outputs
Zero offset U
Gain factor k
Quantization level U
0
0
DAC
ADC
OFF
v
LSB
13
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