DAC7541 Burr-Brown Corporation, DAC7541 Datasheet - Page 8

• Manufacturer Part Number: DAC7541
• Description: Low Cost 12-Bit CMOS Four-Quadrant Multiplying DIGITAL-TO-ANALOG CONVERTER
• Manufacturer: Burr-Brown Corporation

DIGITALLY CONTROLLED GAIN BLOCK
The DAC7541A may be used in a digitally controlled gain
block as shown in Figure 7. This circuit gives a range of gain
from one (all bits = one) to 4096 (LSB = one). The transfer
function is:
All bits off is an illegal state, as division by zero is impos-
sible (no op amp feedback). Also, errors increase as gain
increases, and errors are minimized at major carries (only
one bit on at a time).
V
OUT
®
=
DAC7541A
B
2
1
+
B
4
2
+
–V
B
8
IN
3
+ • • • +
4096
B
12
8
FIGURE 7. Digitally Programmable Gain Block.
V
IN
18
1
DAC7541A
Bits 1 to 12
OPA604
2
3
16
17
V
V
OUT
DD