LTC1599BIN View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1599BIN' PDF : 20 Pages View PDF
LTC1599
APPLICATIONS INFORMATION
configured in unipolar or bipolar modes of operation
(Figures 1 and 3). These are the changes the op amp can
cause to the INL, DNL, unipolar offset, unipolar gain error,
bipolar zero and bipolar gain error. Table 4 contains a
partial list of LTC precision op amps recommended for use
with the LTC1599. The two sets of easy-to-use design
equations simplify the selection of op amps to meet the
system’s specified error budget. Select the amplifier from
Table 4 and insert the specified op amp parameters in
either Table 2 or Table 3. Add up all the errors for each
category to determine the effect the op amp has on the
accuracy of the LTC1599. Arithmetic summation gives an
(unlikely) worst-case effect. RMS summation produces a
more realistic effect.
Op amp offset will contribute mostly to output offset and
gain error and has minimal effect on INL and DNL. For the
LTC1599, a 500µV op amp offset will cause about 0.55LSB
INL degradation and 0.15LSB DNL degradation with a 10V
full-scale range (20V range in bipolar). For the LTC1599
configured in the unipolar mode, the same 500µV op amp
offset will cause a 3.3LSB zero-scale error and a 3.45LSB
gain error with a 10V full-scale range.
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 amp’s data sheet to find the worst-case VOS and IB
over temperature. Then, plug these numbers in the VOS
and IB equations from Table 2 or Table 3 and calculate the
temperature induced effects.
For applications where fast settling time is important,
Application Note 74, entitled “Component and Measure-
ment Advances Ensure 16-Bit DAC Settling Time,” offers
a thorough discussion of 16-bit DAC settling time and op
amp selection.
Table 2. Easy-to-Use Equations Determine Op Amp Effects on DAC Accuracy in Unipolar Applications
OP AMP
INL (LSB)
DNL (LSB)
UNIPOLAR OFFSET (LSB)
UNIPOLAR GAIN ERROR (LSB)
VOS (mV)
IB (nA)
AVOL (V/V)
VOS • 1.2 • (10V/VREF)
IB • 0.00055 • (10V/VREF)
10k/AVOL
VOS • 0.3 • (10V/VREF)
IB • 0.00015 • (10V/VREF)
3k/AVOL
VOS • 6.6 • (10V/VREF)
IB • 0.065 • (10V/VREF)
0
VOS • 6.9 • (10V/VREF)
0
131k/AVOL
Table 3. Easy-to-Use Equations Determine Op Amp Effects on DAC Accuracy in Bipolar Applications
OP AMP
INL (LSB)
DNL (LSB)
BIPOLAR ZERO ERROR (LSB)
VOS1 (mV)
IB1 (nA)
AVOL1
VOS2 (mV)
IB2 (nA)
AVOL2
VOS1 • 1.2 • (10V/VREF)
IB1 • 0.00055 • (10V/VREF)
10k/AVOL
0
0
0
VOS1 • 0.3 • (10V/VREF)
IB1 • 0.00015 • (10V/VREF)
3k/AVOL1
0
0
0
VOS1 • 9.9 • (10V/VREF)
IB1 • 0.065 • (10V/VREF)
0
VOS2 • 6.7 • (10V/VREF)
IB2 • 0.065 • (10V/VREF)
65k/AVOL2
BIPOLAR GAIN ERROR (LSB)
VOS1 • 6.9 • (10V/VREF)
0
196k/AVOL1
VOS2 • 13.2 • (10V/VREF)
IB2 • 0.13 • (10V/VREF)
131k/AVOL2
Table 4. Partial List of LTC Precision Amplifiers Recommended for Use with the LTC1599, with Relevant Specifications
Amplifier Specifications
VOS
AMPLIFIER
µV
VOLTAGE CURRENT SLEW GAIN BANDWIDTH tSETTLING
IB
AOL
NOISE
NOISE
RATE
PRODUCT
with LTC1599
nA
V/mV
nV/√Hz
pA/√Hz
V/µs
MHz
µs
LT1001
25
2
800
10
0.12
0.25
0.8
120
LT1097
50
0.35
1000
14
0.008
0.2
0.7
120
LT1112 (Dual) 60
0.25
1500
14
0.008
0.16
0.75
115
LT1124 (Dual) 70
20
4000
2.7
0.3
4.5
12.5
19
LT1468
75
10
5000
5
0.6
22
90
2.5
POWER
DISSIPATION
mW
46
11
10.5/Op Amp
69/Op Amp
117
sn1599 1599fs
10
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