MCP4922-E/SL Microchip Technology Inc., MCP4922-E/SL Datasheet - Page 22

• Manufacturer Part Number: MCP4922-E/SL
• Description: DUAL 12-BIT DAC WITH SPI INTERACE
• Manufacturer: Microchip Technology Inc.

Specifications of MCP4922-E/SL

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

MCP4921/4922
6.4.1.2
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, then the resolution is sacri-
ficed without consequences. If greater accuracy is
needed, then the output range will need to be reduced
to increase the resolution around the desired threshold.
EXAMPLE 6-2:
DS21897B-page 22
Thevenin
Equivalent
SPI™
V
Building a “Window” DAC
REF
3
MCP492X
V
V
DD
OUT
Single-Supply “Window” DAC.
R
V
V
23
23
trip
=
=
=
V
=
REF
------------------
R
(
----------------------------------------------------- -
V
R
V
------------------------------------------- -
V
2
CC+
2
OUT
+
OUT
G
R
R
3
-------
2
R
D
R
3
12
R
R
2
2
2
23
)
+
R
+
+
+
R
1
R
(
23
R
R
V
V
3
3
2
23
CC-
V
V
R
CC+
CC-
1
R
3
)
R
sense
V
OUT
If the threshold is not near V
a “window” around the threshold has several advan-
tages. One simple method to create this “window” is to
use a voltage divider network with a pull-up and pull-
down resistor.
illustrates this concept.
The MCP492X’s low, ±0.75 (max.) DNL performance
is critical to meet calibration accuracy in production.
R
0.1 µF
1
V
trip
V
23
G = Gain select (1x or 2x)
D = Digital value of DAC (0 – 4096)
R
23
V
Example 6-2 and
O
Comparator
© 2007 Microchip Technology Inc.
V
V
CC+
CC-
REF
or AV
SS
, then creating
Example 6-4