Datasheet

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APPLICATION INFORMATION
V
OUT
+
ǒ
D
32768
* 1
Ǔ
V
REF
DAC8812
(SeeNote A)
Cross-Reference
DAC8812
SBAS349B – AUGUST 2005 – REVISED FEBRUARY 2007
The DAC8812, a 2-quadrant multiplying DAC, can be used to generate a unipolar output. The polarity of the
full-scale output I
OUT
is the inverse of the input reference voltage at V
REF
.
Some applications require full 4-quadrant multiplying capabilities or bipolar output swing, as shown in Figure 35 .
An additional external op amp (A2) is added as a summing amp. In this circuit, the first and second amps (A1
and A2) provide a gain of 2X that widens the output span to 20 V. A 4-quadrant multiplying circuit is
implemented by using a 10-V offset of the reference voltage to bias A2. According to the following circuit transfer
equation (Equation 2 ), input data (D) from code 0 to full scale produces output voltages of V
OUT
= –10 V to
V
OUT
= 10 V.
A. Figure represents one channel only. X is channel A or B (i.e. V
REF
x = V
REF
A or V
REF
B).
Figure 35. Four-Quadrant Multiplying Application Circuit
The DAC8812 has an industry-standard pinout. Table 4 provides the cross-reference information.
Table 4. Cross-Reference
SPECIFIED CROSS-
INL DNL TEMPERATURE PACKAGE PACKAGE REFERENCE
PRODUCT (LSB) (LSB) RANGE DESCRIPTION OPTION PART NUMBER
16-Lead Thin Shrink
DAC8812ICPW ± 1 ± 1 –40 ° C to 85 ° C TSSOP-16 N/A
Small-Outline Package
16-Lead Thin Shrink
DAC8812IBPW ± 2 ± 1 –40 ° C to 85 ° C TSSOP-16 AD5545BRU
Small-Outline Package
15
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