MCP4725 Microchip Technology, MCP4725 Datasheet - Page 12

• Manufacturer Part Number: MCP4725
• Description: 12-Bit Digital-to-Analog Converter
• Manufacturer: Microchip Technology

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MCP4725
FIGURE 4-2:
4.5
Offset error
age output when the digital input code is zero. This
error affects all codes by the same amount. In the
MCP4725, the offset error is not trimmed at the factory.
However, it can be calibrated by software in application
circuits.
FIGURE 4-3:
4.6
Gain error (see
the actual full-scale output voltage from the ideal output
voltage on the transfer curve. The gain error is
calculated after nullifying the offset error, or full scale
error minus the offset error.
The gain error indicates how well the slope of the actual
transfer function matches the slope of the ideal transfer
function. The gain error is usually expressed as percent
of full-scale range (% of FSR) or in LSB.
DS22039C-page 12
Offset
Error
Analog
Output
(LSB)
Analog
Output
Offset Error
Gain Error
6
5
0
7
4
3
2
1
0
000
(Figure
Actual Transfer Function
001
Actual Transfer Function
Ideal Transfer Function
Figure
DNL = 2LSB
4-3) is the deviation from zero volt-
010
DAC Input Code
DNL Accuracy.
Offset Error.
4-4) is the difference between
011
DNL = 0.5 LSB
DAC Input Code
Ideal Transfer Function
100 101
110
111
In the MCP4725, the gain error is not calibrated at the
factory and most of the gain error is contributed by the
output op amp saturation near the code range beyond
4000. For the applications which need the gain error
specification less than 1% maximum, the user may
consider using the DAC code range between 100 and
4000 instead of using full code range (code 0 to 4095).
The DAC output of the code range between 100 and
4000 is much linear than full-scale range (0 to 4095).
The gain error can be calibrated by software in applica-
tions.
4.7
Full-scale error
plus gain error. It is the difference between the ideal
and measured DAC output voltage with all bits set to
one (DAC input code = FFFh).
EQUATION 4-4:
FIGURE 4-4:
Error.
4.8
Gain error drift is the variation in gain error due to a
change in ambient temperature. The gain error drift is
typically expressed in ppm/
Output
Analog
Where:
V
V
Ideal
REF
0
Full-Scale Error (FSE)
Actual Transfer Function
Gain Error Drift
=
=
FSE
(Figure
(V
The reference voltage.
V
REF
REF
=
Gain Error and Full-Scale
= V
) (1 - 2
(
-------------------------------------- -
© 2007 Microchip Technology Inc.
4-4) is the sum of offset error
V
OUT
DAC Input Code
DD
o
C.
LSB
after Offset Error Removed
-n
in the MCP4725
Actual Transfer Function
–
Ideal Transfer Function
) - V
V
Ideal
OFFSET
)
Full-Scale
Error
Gain Error