AD565A/AD566A
REV.E
–10–
FIGURE 6. OTHER VOLTAGE RANGES
The AD566A can also be easily configured for a unipolar 0 V to
+5 V range or ±2.5 V and ± 10 V bipolar ranges by using the
additional 5 kΩ application resistor provided at the 20 V span R
terminal, Pin 11. For a 5 V span (0 V to +5 V or ± 2.5 V), the two
5 kΩ resistors are used in parallel by shorting Pin 11 to Pin 9 and
connecting Pin 10 to the op amp output and the bipolar offset
resistor either to ground for unipolar or to V
REF
for the bipolar
range. For the ±10 V range (20 V span), use the 5 kΩ resistors in
series by connecting only Pin 11 to the op amp output and the
bipolar offset connected as shown. The ± 10 V option is shown
in Figure 6.
Table I. Digital Input Codes
DIGITAL INPUT ANALOG OUTPUT
MSB LSB Straight Binary Offset Binary Twos Complement*
0 0 0 0 0 0 0 0 0 0 0 0 Zero –FS Zero
0 1 1 1 1 1 1 1 1 1 1 1 Mid Scale – 1 LSB Zero – 1 LSB +FS – 1 LSB
1 0 0 0 0 0 0 0 0 0 0 0 +1/2 FS Zero –FS
1 1 1 1 1 1 1 1 1 1 1 1 +FS – l LSB +FS – 1 LSB Zero – 1 LSB
*Inverts the MSB of the offset binary code with an external inverter to obtain twos complement.
19.95k⍀
20k⍀
0.5mA
I
REF
DAC
I
OUT
=
4 ⴛ I
REF
ⴛ CODE
AD566A
9.95k⍀
5k⍀
8k⍀
I
O
20V SPAN
10V SPAN
DAC
OUT
POWER
GND
–V
EE
REF
GND
BIPOLAR OFF
5k⍀
CODE
INPUT
LSB
MSB
R2
5k⍀
10pF
AD509
2.4k⍀
7.5V
E
REF
AD561
–V
REF
IN
R1
5k⍀
14k⍀
*
THE PARALLEL COMBINATION OF THE BIPOLAR OFFSET RESISTOR
AND R3 ESTABLISHES A CURRENT TO BALANCE THE MSB CURRENT.
THE EFFECT OF TEMPERATURE COEFFICIENT MISMATCH BETWEEN
THE BIPOLAR RESISTOR COMBINATION AND DAC RESISTORS IS
EXPANDED ON PREVIOUS PAGE.
R3
26k⍀*
Figure 6.
±
10 V Voltage Output
