LTC1599BIN View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1599BIN' PDF : 20 Pages View PDF
LTC1599
APPLICATIONS INFORMATION
VREF
5+
7
1/2 LT1112
6–
5V
0.1µF
4
3
2 1 20 5
6
R1
RCOM
R2 REF VCC ROFS
RFB
15pF
8
R1
DATA
INPUTS
14 TO 18,
21 TO 23
R2
LTC1599
13
MLBYTE
MLBYTE
WR LD CLR CLVL
WR
LD
CLR
CLVL
12 11 24 10
ROFS RFB
16-BIT DAC
IOUT1 7
2–
1
1/2 LT1112
IOUT2F 8 3 +
IOUT2S 9
19
DGND
Bipolar Offset Binary Code Table
DIGITAL INPUT
BINARY NUMBER
IN DAC REGISTER
MSB
LSB
1111 1111 1111 1111
1000 0000 0000 0001
1000 0000 0000 0000
0111 1111 1111 1111
0000 0000 0000 0000
ANALOG OUTPUT
VOUT
VREF (32,767/32,768)
VREF (1/32,768)
0V
–VREF (1/32,768)
–VREF
VOUT
–VREF TO VREF
1599 F03
Figure 3. Bipolar Operation (4-Quadrant Multiplication) VOUT = – VREF to VREF
Precision Voltage Reference Considerations
Much in the same way selecting an operational amplifier
for use with the LTC1599 is critical to the performance of
the system, selecting a precision voltage reference also
requires due diligence. As shown in the section describing
the basic operation of the LTC1599, the output voltage of
the DAC circuit is directly affected by the voltage reference;
thus, any voltage reference error will appear as a DAC
output voltage error.
There are three primary error sources to consider when
selecting a precision voltage reference for 16-bit applica-
tions: output voltage initial tolerance, output voltage tem-
perature coefficient and output voltage noise.
Initial reference output voltage tolerance, if uncorrected,
generates a full-scale error term. Choosing a reference
with low output voltage initial tolerance, like the LT1236
(±0.05%), minimizes the gain error caused by the refer-
ence; however, a calibration sequence that corrects for
system zero- and full-scale error is always recommended.
12
A reference’s output voltage temperature coefficient af-
fects not only the full-scale error, but can also affect the
circuit’s INL and DNL performance. If a reference is
chosen with a loose output voltage temperature coeffi-
cient, then the DAC output voltage along its transfer
characteristic will be very dependent on ambient condi-
tions. Minimizing the error due to reference temperature
coefficient can be achieved by choosing a precision refer-
ence with a low output voltage temperature coefficient
and/or tightly controlling the ambient temperature of the
circuit to minimize temperature gradients.
As precision DAC applications move to 16-bit and higher
performance, reference output voltage noise may contrib-
ute a dominant share of the system’s noise floor. This in
turn can degrade system dynamic range and signal-to-
noise ratio. Care should be exercised in selecting a voltage
reference with as low an output noise voltage as practical
for the system resolution desired. Precision voltage refer-
ences, like the LT1236, produce low output noise in the
0.1Hz to 10Hz region, well below the 16-bit LSB level in 5V
sn1599 1599fs
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