MCP4728 Microchip Technology Inc., MCP4728 Datasheet - Page 47

• Manufacturer Part Number: MCP4728
• Description: 12-bit, Quad Digital-to-analog Converter With Eeprom Memory
• Manufacturer: Microchip Technology Inc.

6.0
6.1
The resolution is the number of DAC output states that
divide the full scale range. For the 12-bit DAC, the
resolution is 2
to 4095.
6.2
The least significant bit or the ideal voltage difference
between two successive codes.
EQUATION 6-1:
6.3
Integral nonlinearity (INL) error is the maximum
deviation of an actual transfer function from an ideal
transfer function (straight line). In the MCP4728, INL is
calculated using two end-points (zero and full scale).
INL can be expressed as a percentage of full scale
range (FSR) or in fraction of an LSB. INL is also called
relative accuracy.
the INL error in LSB and
of INL accuracy.
EQUATION 6-2:
© 2009 Microchip Technology Inc.
Where
Where:
INL is expressed in LSB
V
V
V
Ideal
OUT
REF
n
TERMINOLOGY
Resolution
LSB
Integral Nonlinearity (INL)
=
=
=
LSB
=
=
12
The number of digital input bits,
n = 12 for MCP4728.
2.048V If internal reference is
, meaning the DAC code ranges from 0
INL
V
=
Code*LSB
The output voltage measured at
the given input code
DD
Equation 6-2
=
=
V
------------ -
=
REF
2
(
---------------------------------------------------------
(
---------------------------------------------------------
n
V
V
INL ERROR
(
-------------------------------------- -
If external reference is
selected
selected
Full Scale
Full Scale
V
Figure 6-1
OUT
LSB
2
4095
–
12
shows how to calculate
–
–
V
–
Ideal
V
V
1
Zero Scale
Zero Scale
shows an example
)
)
)
FIGURE 6-1:
6.4
Differential nonlinearity (DNL) error (see
the measure of step size between codes in actual
transfer function. The ideal step size between codes is
1 LSB. A DNL error of zero would imply that every code
is exactly 1 LSB wide. If the DNL error is less than
1 LSB, the DAC guarantees monotonic output and no
missing codes. The DNL error between any two
adjacent codes is calculated as follows:
EQUATION 6-3:
Where:
DNL is expressed in LSB.
Analog
Output
Δ
(LSB)
V
OUT
6
5
7
1
0
4
3
2
Differential Nonlinearity (DNL)
000
INL = 0.5 LSB
=
001
DNL
The measured DAC output
voltage difference between two
adjacent input codes.
010
Actual Transfer Function
Ideal Transfer Function
INL Accuracy.
=
DNL ERROR
011
DAC Input Code
ΔV
--------------------------------- -
INL = - 1 LSB
OUT
100 101
LSB
MCP4728
–
INL = < -1 LSB
LSB
DS22187A-page 47
110
Figure
111
6-2) is