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| LTC2641 Datasheet, PDF (13/20 Pages) Linear Technology – 16-/14-/12-Bit VOUT DACs in 3mm × 3mm DFN | |||
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LTC2641/LTC2642
APPLICATIONS INFORMATION
Bipolar Conï¬guration
Figure 3 shows a typical bipolar DAC application for the
LTC2642. The on-chip bipolar offset/gain resistors, RFB
and RINV, are connected to an external ampliï¬er to produce
a bipolar output swing from âVREF to VREF at the RFB pin.
The ampliï¬er circuit provides a gain of +2 from the VOUT
pin, and gain of â1 from VREF. Tables 2a, 2b and 2c show
the bipolar offset binary code tables for 16-bit, 14-bit and
12-bit operation.
5V/3V
9
VDD
LTC2642-16
2 CS
3 SCLK
4 DIN
5 CLR
VREF
2.5V
0.1μF
1
REF
0.1μF
4.7μF
RFB 8
16-BIT DAC
INV 7
VOUT 6
OUT
IN 5V
LT1019CS8-2.5
GND
C1
10pF
â
5V 0.1μF
1/2 LT1678
+
0.1μF
BIPOLAR VOUT
â2.5V TO 2.5V
â5V
GND
10
26412 F02
Figure 3. 16-Bit Bipolar Output (LTC2642-16) VOUT = âVREF to VREF
Table 2a. 16-Bit Bipolar Offset Binary
Code Table (LTC2642-16)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
MSB
LSB
ANALOG OUTPUT
(VOUT)
1111 1111 1111 1111 VREF (32,767/32,768)
1000 0000 0000 0001 VREF (1/32,768)
1000 0000 0000 0000 0V
0111 1111 1111 1111 âVREF (1/32,768)
0000 0000 0000 0000 âVREF
Table 2b. 14-Bit Bipolar Offset Binary
Code Table (LTC2642-14)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
MSB
LSB
ANALOG OUTPUT
(VOUT)
1111 1111 1111 11xx VREF (8,191/8,192)
1000 0000 0000 01xx VREF (1/8,192)
1000 0000 0000 00xx 0V
0111 1111 1111 11xx âVREF (1/8,192)
0000 0000 0000 00xx âVREF
Table 2c. 12-Bit Bipolar Offset Binary
Code Table (LTC2642-12)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
MSB
LSB
ANALOG OUTPUT
(VOUT)
1111 1111 1111 xxxx VREF (2,047/2,048)
1000 0000 0001 xxxx VREF (1/2,048)
1000 0000 0000 xxxx 0V
0111 1111 1111 xxxx âVREF (1/2048)
0000 0000 0000 xxxx âVREF
26412f
13
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