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IBIS4-6600
Datasheet
Cypress Semiconductor Corporation
3901 North First Street
San Jose, CA 95134
408-943-2600
Contact: info@Fillfactory.com
Document #: 38-05708 Rev.**(Revision 1.3 )
Page 18 of 63
3.5.4 Offset DACs
Figure 10 shows how the DAC registers influence the black reference voltages of the
two different channels. The offset is mainly given through DAC_raw. DAC_fine can
be used to shift the reference voltage of bus 2 up or down to compensate for different
offsets in the two channels.
DAC_raw
DAC_RAW_REG<0:7>
out
DAC_fine
VDDA
out
10K
200K
50K
50K
10K
200K
blackref
bus1
blackref
bus2
GNDA
DAC_FINE_REG<0:7>
rcal
rcal
pad RCAL_DAC_OUT
floating
RCAL
VCAL
+
Figure 10: Offset for the two channels through DAC_raw and DAC_fine
Assume that Voutfull is the voltage that depends on the bit values that are applied to the
DAC and ranges from
)
11111111
(
)
2
1
1
(
)
00000000
(
0
:
8
values
bit
VDDA
values
bit
V
outfull
−
→
Externally, the output range of DAC_raw can be changed by connecting a resistor Rcal
to RCAL_DAC_OUT and applying a voltage Vcal. The output voltage Vout of DAC_raw
follows relation (R = 10 kΩ)
cal
cal
outfull
cal
cal
out
V
R
R
R
V
R
R
R
R
V
+
+
+
+
=
2
2
Special case: Rcal = ∞
then Vout = Voutfull (e.g. for DAC_fine)