MCP4821T-E/P MICROCHIP [Microchip Technology], MCP4821T-E/P Datasheet - Page 21

• Manufacturer Part Number: MCP4821T-E/P
• Manufacturer: MICROCHIP [Microchip Technology]

6.5.1.2
When calibrating a set point or threshold of a sensor,
rarely does the sensor utilize the entire output range of
the DAC. If the LSb size is adequate to meet the appli-
cation’s accuracy needs, the resolution is sacrificed
without consequences. If greater accuracy is needed,
then the output range will need to be reduced to
increase the resolution around the desired threshold. If
the threshold is not near V
EXAMPLE 6-2:
© 2005 Microchip Technology Inc.
Thevenin
Equivalent
SPI™
Building a “Window” DAC
3
V
MCP482X
V
OUT
DD
Single-Supply “Window” DAC.
R
V
V
23
23
trip
=
=
=
REF
2.048 G
=
------------------
R
----------------------------------------------------- -
, 2V
V
R
V
------------------------------------------- -
2
CC+
V
2
OUT
+
R
OUT
R
3
REF
R
R
3
R
R
-------
2
2
D
2
23
12
2
+
+
+
or AV
R
R
+
R
23
1
V
V
3
R
R
23
CC-
3
2
R
SS
V
V
R
1
CC+
CC-
, then
3
R
SENSE
V
OUT
creating a “window” around the threshold has several
advantages. One simple method to create this
“window” is to use a voltage divider network with a pull-
up
Example 6-4 illustrates this concept.
The MCP482X family’s low ±0.75 (max.) DNL
performance is critical to meet calibration accuracy in
production.
MCP4821/MCP4822
R
and
1
0.1 µF
V
TRIP
V
pull-down
23
G = Gain select (1x or 2x)
D = Digital value of DAC (0 – 4096)
R
23
V
O
Comparator
resistor.
V
V
CC+
CC-
Example 6-2
DS21953A-page 21
and