HT46R46/C46/R47/C47/R48A/C48A/R49
Rev. 1.41
33
December 30, 2008
A/D Transfer Function
As the HT46R46 device contain an 8-bit A/D converter,
their full-scale converted digitized value is equal to
0FFH. Since the full-scale analog input value is equal to
the voltage, this gives a single bit analog input value of
V
DD
/256. For the other devices which each contain a
9-bit A/D converter, their full-scale converted digitised
value is equal to 1FFH giving a single bit analog input
value of V
DD
/512. The following graphs show the ideal
transfer function between the analog input value and the
digitised output value for the A/D converters.
Note that to reduce the quantisation error, a 0.5 LSB off-
set is added to the A/D Converter input. Except for the
digitised zero value, the subsequent digitised values will
change at a point 0.5 LSB below where they would
change without the offset, and the last full scale digitised
value will change at a point 1.5 LSB below the V
DD
level.
1 F E H
( )
A / D C o n v e r s i o n
R e s u l t
1 F F H
1 F D H
0 3 H
0 2 H
0 1 H
0 . 5 L S B
0
1
2
3
5 0 9
5 1 0
5 1 1
5 1 2
A n a l o g I n p u t V o l t a g e
1 . 5 L S B
V
D D
5 1 2
Ideal A/D Transfer Function
-
Other Devices
F E H
( )
A / D C o n v e r s i o n
R e s u l t
F F H
F D H
0 3 H
0 2 H
0 1 H
0 . 5 L S B
0
1
2
3
2 5 3
2 5 4
2 5 5
2 5 6
A n a l o g I n p u t V o l t a g e
1 . 5 L S B
V
D D
2 5 6
Ideal A/D Transfer Function
-
HT46R46
