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17. Raw ADC Values and Calibration
The raw ADC values, selectable from the ‘
’ setting, can be used to adjust, or confirm, the
calibration settings of the RD60xx.
Vout = ADC(V) * backVoltageScale / 100000 - backVoltageZero
Iout = ADC(I) * backCurrentScale / 100000 - backCurrentZero
For example, let's calibrate the "backVoltage" values:
1) Find
ADC(V)
0
,
the ADC ‘Zero’ value:
● Ensure the output is OFF and the output capacitors are discharged.
○ Observe the value of ADC(V) for a while.
● Take the highest value and add 1.
(In this example, the highest value observed was: 143.)
○
ADC(V)
0
= 143 + 1 =
144
2) Find
ADC(V)
x
,
the ADC reading of a known (calibrated) value.
(For this example let it be
50
V)
● Set output to
50.00
V and turn ON.
● Using the
“
ENCODER
”
Knob, adjust output voltage to be as close to 50V, as measured
using a calibrated multimeter.
○ Observe the value of ADC(V) for a while.
● Take the most stable value (usually a middle one).
(In this example,
ADC(V)
x
=
29109
)
3) Calculate calibration constants:
Scale
= (Calibrated Value *
100,000
) / (ADC(V)
x
- ADC(V)
0
)
(In this example, ‘Calibrated Value’ =
50
V, in tens of mV =
5000
)
=
(5000 * 100,000) / (29109 - 144)
=
17262
Zero
=
(
ADC(V)
0
* Scale)
/ 100,000
=
(144 * 17262) / 100,000
=
24
Notes:
When calculating with the ADC values for current:
● RD60
06
the ‘Calibrated Value’ is in:
mA
(ie. 1А = 1000)
● RD60
1x
the ‘Calibrated Value’ is in:
tens of mA
(ie. 1A = 100)
