
LTC2641/LTC2642
14
26412fc
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, RFB
andRINV,areconnectedtoanexternalamplifiertoproduce
a bipolar output swing from –VREF to VREF at the RFB pin.
The amplifier circuit provides a gain of +2 from the VOUT
pin, and gain of –1 from VREF. 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
VREF
2.5V
VDD
LTC2642-16
BIPOLAR VOUT
–2.5V TO 2.5V
4.7F
C1
10pF
0.1F
REF
1
6
10
VOUT
7
INV
8
RFB
GND
26412 F02
0.1F
9
5
4
3
2
CS
SCLK
DIN
CLR
LT1019CS8-2.5
GND
OUT
5V
IN
Table 2b. 14-Bit Bipolar Offset Binary
Code Table (LTC2642-14)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(VOUT)
MSB
LSB
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 –VREF (1/8,192)
0000 0000 0000 00xx –VREF
Figure 3. 16-Bit Bipolar Output (LTC2642-16) VOUT = –VREF to VREF
Table 2a. 16-Bit Bipolar Offset Binary
Code Table (LTC2642-16)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(VOUT)
MSB
LSB
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 –VREF (1/32,768)
0000 0000 0000 0000 –VREF
Table 2c. 12-Bit Bipolar Offset Binary
Code Table (LTC2642-12)
DIGITAL INPUT
BINARY NUMBER
IN DAC LATCH
ANALOG OUTPUT
(VOUT)
MSB
LSB
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 –VREF (1/2048)
0000 0000 0000 xxxx –VREF