Datasheet
LTC2641/LTC2642
14
26412fd
For more information www.linear.com/LTC2641
APPLICATIONS INFORMATION
Bipolar Configuration
Figure 3 shows a typical bipolar DAC application for the
LTC2642. The on-chip bipolar offset/gain resistors, R
FB
and R
INV
, are connected to an external amplifier to produce
a bipolar output swing from –V
REF
to V
REF
at the R
FB
pin.
The amplifier circuit provides a gain of +2 from the V
OUT
pin, and gain of –1 from V
REF
. Tables 2a, 2b and 2c show
the bipolar offset binary code tables for 16-bit, 14-bit and
12-bit operation.
–
+
16-BIT DAC
1/2 LT1678
5V
–5V
5V/3V
V
REF
2.5V
V
DD
LTC2642-16
BIPOLAR V
OUT
–2.5V TO 2.5V
4.7µF
C1
10pF
0.1µF
0.1µF
REF
1
6
10
V
OUT
7
INV
8
R
FB
GND
26412 F02
0.1µF
0.1µF
9
5
4
3
2
CS
SCLK
DIN
CLR
LT1019CS8-2.5
GND
OUT 5VIN
Table 2b. 14-Bit Bipolar Offset Binary
Code Table (LTC2642-14)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(V
OUT
)
MSB LSB
1111 1111 1111 11xx V
REF
(8,191/8,192)
1000 0000 0000 01xx V
REF
(1/8,192)
1000 0000 0000 00xx 0V
0111 1111 1111 11xx –V
REF
(1/8,192)
0000 0000 0000 00xx –V
REF
Figure 3. 16-Bit Bipolar Output (LTC2642-16) V
OUT
= –V
REF
to V
REF
Table 2a. 16-Bit Bipolar Offset Binary
Code Table (LTC2642-16)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(V
OUT
)
MSB LSB
1111 1111 1111 1111 V
REF
(32,767/32,768)
1000 0000 0000 0001 V
REF
(1/32,768)
1000 0000 0000 0000 0V
0111 1111 1111 1111 –V
REF
(1/32,768)
0000 0000 0000 0000 –V
REF
Table 2c. 12-Bit Bipolar Offset Binary
Code Table (LTC2642-12)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(V
OUT
)
MSB LSB
1111 1111 1111 xxxx V
REF
(2,047/2,048)
1000 0000 0001 xxxx V
REF
(1/2,048)
1000 0000 0000 xxxx 0V
0111 1111 1111 xxxx –V
REF
(1/2048)
0000 0000 0000 xxxx –V
REF
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