MB4053 Fujitsu Microelectronics, Inc., MB4053 Datasheet - Page 11

• Manufacturer Part Number: MB4053
• Description: 6-channel 8-bit A/D Converter
• Manufacturer: Fujitsu Microelectronics, Inc.

ZERO OFFSET AND FULL-SCALE FACTOR CORRECTIONS
High precision conversions can be achieved by correcting for zero offset and full scale factor as follows:
The channel select address (A
and converted. This results in ramp time t
converted. This results in ramp time, t
This results in ramp time t
needed each time a channel is converted but only as required for calibration. The relationships between the
inputs and ramp times are shown below.
The conversion error can then be minimized by using the above results in the expression below to calculate the
corrected analog input voltage.
The GND and V
a channel (I
1
to I
REF
6
) is converted.
conversion sequence is arbitary, the GND and V
X
. This conversion sequence is arbitrary and the GND and V
Where: V
0
V
to A
REF
V
IN
+ V
+ V
2
(V
REF
V
V
V
V
V
V
) is set to 000. Ground (GND) is selected (internally) as the analog input
BE1
BE1
BE1
BE2
IN
IN
REF
BE1
BE2
CH
. Finally the desired analog input (one of I
)
= Analog input voltage to be measured
C
= C
V
= Reference voltage
= Shift voltage in sample/ramp amplifer
= Threshold voltage of comparator
R
= (V
CH
(V
(V
(V
(V
(V
. Next the address is set to 111. V
(V
(V
H
BE1
REF
IN
REF
IN
REF
t
voltage
IN
Z
REF
)
+ V
C
)
)
)
C
)
C
+ V
C
)
= t
C
C
= t
= t
BE1
=
X
BE1
Z
REF
t
– t
)
X
t
C
t
REF
)
t
X
REF
C
t
= t
Z
X
– t
– t
= t
– t
– t
– t
X
Z
Z
REF
Z
Z
Z
t
REF
REF
conversions not being needed each time
t
R
REF
1
to I
is selected (internally) and
6
) is selected and converted.
REF
conversions are not
MB4053
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