dac1008 National Semiconductor Corporation, dac1008 Datasheet - Page 12

• Manufacturer Part Number: dac1008
• Description: Up Compatible, Double-buffered D To A Converters
• Manufacturer: National Semiconductor Corporation

5 4 2 Current Switching with Bipolar Output Voltage
The circuit of Figure 12 shows the 3 adjustments needed
The first step is to set all of the digital inputs LOW (to force
I
inverting input (pin 2) of 0A1 Next with a code of all zeros
still applied adjust ‘‘
V
be opposite that of the applied reference
Finally set all of the digital inputs HIGH and adjust ‘‘
adj ’’ for V
this time will be the same as that of the reference voltage
The addition of the 200X resistor in series with the V
of the DAC is to force the circuit gain error from the DAC to
be negative This insures that adding resistance to R
the 500X pot will always compensate the gain error of the
DAC
OUT1
OUT
e
to 0) and then trim ‘‘zero adj ’’ for zero volts at the
g
l
OUT
(ideal V
e
V
REF
REF
FIGURE 13 Full Scale Adjust
b
FIGURE 12 Full Scale Adjust
)
l
(511 512) The sign of the output at
FS adj ’’ the reference voltage for
The sign of the output voltage will
REF
fb
Voltage Switching with a Unipolar Output Voltage
a
with
Current Switching with Bipolar Output Voltage
pin
FS
12
5 4 3 Voltage Switching with a Unipolar Output Voltage
Refer to the circuit of Figure 13 and set all digital inputs
LOW Trim the ‘‘zero adj ’’ for V
set all digital inputs HIGH and trim the ‘‘FS Adj ’’ for
V
5 4 4 Voltage Switching with a Bipolar Output Voltage
Refer to Figure 14 and set all digital inputs LOW Trim the
‘‘
HIGH and trim the ‘‘
V
all the rest LOW Adjust V
recheck the full-scale values
b
OUT
DC
FS Adj ’’ for V
Test the zero by setting the MS digital input HIGH and
e
(
a
V)
b
V

REF s
1
a
OUT
R
R
V
1
2
OUT s
a
eb
J
1023
1024
FS Adj ’’ for V
a
2 5 V
OS
V
REF
of amp
DC

OUT
511
512
Then set all digital inputs
J
e
OUT
0 V
3 if necessary and
e a
DC g
2 5 (511 512)
1 mV Then
TL H 5688 – 14