12
LTC1588/LTC1589/LTC1592
1588992fa
While not directly addressed by the simple equations in
Tables 2 and 3, temperature effects can be handled just as
easily for unipolar and bipolar applications. First, consult
an op amps data sheet to find the worst-case V
OS
and I
B
over temperature. Then, plug these numbers in the V
OS
and I
B
equations from Table 3 and calculate the tempera-
ture induced effects.
For applications where fast settling time is important, Appli-
cation Note 74, entitled
Component and Measurement
Advances Ensure 16-Bit DAC Settling Time
, offers a thor-
ough discussion of 16-bit DAC settling time and op amp
selection.
Precision Voltage Reference Considerations
Much in the same way selecting an operational amplifier
for use with the LTC1592 is critical to the performance of
the system, selecting a precision voltage reference also
requires due diligence. The output voltage of the LTC1592
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
APPLICA TIO S I FOR A TIO
WUUU
Table 4. Partial List of LTC Precision Amplifiers Recommended for Use with the LTC1588/LTC1589/LTC1592,
with Relevant Specifications
AMPLIFIER SPECIFICATIONS
VOLTAGE CURRENT SLEW GAIN BANDWIDTH t
SETTLING
POWER
V
OS
I
B
A
OL
NOISE NOISE RATE PRODUCT with LTC1592 DISSIPATION
AMPLIFIER mV nA V/mV nV/ Hz pA/ Hz V/ms MHz msmW
LT1001 25 2 800 10 0.12 0.25 0.8 120 46
LT1097 50 0.35 1000 14 0.008 0.2 0.7 120 11
LT1112 (Dual) 60 0.25 1500 14 0.008 0.16 0.75 115 10.5/Op Amp
LT1124 (Dual) 70 20 4000 2.7 0.3 4.5 12.5 19 69/Op Amp
LT1468 75 10 5000 5 0.6 22 90 2.5 117
LT1469 (Dual) 125 10 2000 5 0.6 22 90 2.5 123/Op Amp
()
5V
V
REF
()
5V
V
REF
()
16.5k
A
VOL1
V
OS1
(mV)
I
B1
(nA)
A
VOL1
(V/V)
V
OS2
(mV)
I
B2
(mV)
A
VOL2
(V/V)
V
OS1
¥ 2.4 ¥
I
B1
¥ 0.0003 ¥˚
A1 ¥
0
0
0
()
5V
V
REF
()
5V
V
REF
()
1.5k
A
VOL1
()
66k
A
VOL2
()
131k
A
VOL1
()
131k
A
VOL1
()
131k
A
VOL2
()
131k
A
VOL2
V
OS1
¥ 0.6 ¥
I
B1
¥ 0.00008 ¥˚
A2 ¥
0
0
0
()
5V
V
REF
()
5V
V
REF
V
OS1
¥ 13.2 ¥
I
B1
¥ 0.13 ¥˚
0
0
0
0
()
5V
V
REF
()
5V
V
REF
()
5V
V
REF
V
OS1
¥ 13.2 ¥
I
B1
¥ 0.0018 ¥
A5 ¥
V
OS2
¥ 26.2 ¥
I
B2
¥ 0.1 ¥
()
5V
V
REF
()
5V
V
REF
()
()
()
5V
V
REF
()
5V
V
REF
A3 ¥ V
OS1
¥ 19.8 ¥
I
B1
¥ 0.01 ¥˚
0
A4 ¥ V
OS2
¥ 13.1 ¥
A4 ¥ I
B2
¥ 0.05 ¥˚
A4 ¥
()
5V
V
REF
()
5V
V
REF
()
5V
V
REF
()
5V
V
REF
()
5V
V
REF
V
OS1
¥ 13.2 ¥
I
B1
¥ 0.0018 ¥
A5 ¥
V
OS2
¥ 26.2 ¥
I
B2
¥ 0.1 ¥
Table 3. Easy-to-Use Equations Determine Op Amp Effects on DAC Accuracy in All Output Ranges
Table 2. Variables for Each Output Range That Adjust the
Equations in Table 3
OUTPUT RANGE A1 A2 A3 A4 A5
5V 1.1 2 1
10V 2.2 3 1.5
–5V 2 2 1.2 1 1.5
–10V 4 4 1.2 1 2.5
–2.5V 1 1 1.6 1 1
—2.5V to 7.5V 1.9 3 1 0.5 1.5
