LTC2753_15 datasheet(19/24 Pages) LINER

19 / 24 page

LTC2753

2753f

APPLICATIONS INFORMATION

Op amp offset will contribute mostly to output offset and

gain error, and has minimal effect on INL and DNL. For

example, for the LTC2753-16 with a 5V reference in 5V

unipolar mode, a 250μV op amp offset will cause a 3.3LSB

zero-scale error and a 3.3LSB gain error; but only 0.8LSB

of INL degradation and 0.2LSB of DNL degradation.

While not directly addressed by the simple equations in

Tables 4 and 5, 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 5 and calculate the tempera-

ture-induced effects.

For applications where fast settling time is important, Ap-

plication Note 74, Component and Measurement Advances

Ensure 16-Bit DAC Settling Time, offers a thorough discus-

sion 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 LTC2753 is critical to the performance of

the system, selecting a precision voltage reference also

requires due diligence. The output voltage of the LTC2753

is directly affected by the voltage reference; thus, any

voltage reference error will appear as a DAC output volt-

age error.

There are three primary error sources to consider when

selecting a precision voltage reference for 16-bit appli-

cations: output voltage initial tolerance, output voltage

temperature 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 reference;

however, a calibration sequence that corrects for system

zero- and full-scale error is always recommended.

A reference’s output voltage temperature coefﬁcient af-

fects not only the full-scale error, but can also affect the

circuit’s apparent INL and DNL performance. If a refer-

ence is chosen with a loose output voltage temperature

coefﬁcient, then the DAC output voltage along its transfer

characteristic will be very dependent on ambient conditions.

Minimizing the error due to reference temperature coef-

ﬁcient can be achieved by choosing a precision reference

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 con-

tribute 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 practi-

cal for the system resolution desired. Precision voltage

references, like the LT1236, produce low output noise in

the 0.1Hz to 10Hz region, well below the 16-bit LSB level

in 5V or 10V full-scale systems. However, as the circuit

bandwidths increase, ﬁltering the output of the reference

may be required to minimize output noise.

Table 7. Partial List of LTC Precision References Recommended

for Use with the LTC2753 with Relevant Speciﬁcations

REFERENCE

INITIAL

TOLERANCE

TEMPERATURE

DRIFT

0.1Hz to 10Hz

NOISE

LT1019A-5,

LT1019A-10

±0.05%

5ppm/°C

12μVP-P

LT1236A-5,

LT1236A-10

±0.05%

5ppm/°C

3μVP-P

LT1460A-5,

LT1460A-10

±0.075%

10ppm/°C

20μVP-P

LT1790A-2.5

±0.05%

10ppm/°C

12μVP-P

LTC2753 数据表(PDF) 19 Page - Linear Technology

LTC2753 数据表(HTML) 19 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

数据表下载

链接网址

LTC2753 数据表(PDF) 19 Page - Linear Technology

LTC2753 数据表(HTML) 19 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

数据表 下载

链接网址

数据表下载