Datasheet

11
LTC1821
Figure 2. Bipolar Operation (4-Quadrant Multiplication) V
OUT
= –V
REF
to V
REF
Bipolar Mode
(4-Quadrant Multiplying, V
OUT
= –V
REF
to V
REF
)
The LTC1821 contains on chip all the 4-quadrant resistors
necessary for bipolar operation. 4-quadrant multiplying
APPLICATIONS INFORMATION
WUU
U
operation can be achieved with a minimum of external
components—a capacitor and a single op amp, as shown
in Figure 2. With a fixed 10V reference, the circuit shown
gives a precision bipolar –10V to 10V output swing.
V
CC
LTC1821
R
FB
R
FB
R
OFS
R
OFS
5V
LD
LD
10
9
24 23
718
2
13
15
20
117 16
R1
R
COM
8
6
3
2
REF
11
12
0.1µF
0.1µF
15V
–15V
14
I
OUT
V
OUT
22pF
V
OUT
=
–V
REF
TO V
REF
1821 F02
AGNDF AGNDS
DGND
WR
25 TO 36,
3 TO 6
WR
CLR DNC* DNC*
CLR
V
REF
–
+
16-BIT DAC
R1
R2
16
DATA
INPUTS
0.1µF
19
DNC*
21
NC
22
V
–
V
+
–
+
LT1001
Bipolar Offset Binary Code Table
DIGITAL INPUT
BINARY NUMBER
IN DAC REGISTER
V
REF
(32,767/32,768)
V
REF
(1/32,768)
0V
–V
REF
(1/32,768)
–V
REF
LSB
1111 1111 1111
0000 0000 0001
0000 0000 0000
1111 1111 1111
0000 0000 0000
ANALOG OUTPUT
V
OUT
MSB
1111
1000
1000
0111
0000
*DO NOT CONNECT