MCP4821-E/MS Microchip Technology, MCP4821-E/MS Datasheet - Page 27

• Manufacturer Part Number: MCP4821-E/MS
• Description: IC DAC 12BIT W/SPI 8MSOP
• Manufacturer: Microchip Technology

Specifications of MCP4821-E/MS

• Data Interface: Serial, SPI™
• Settling Time: 4.5µs
• Number Of Bits: 12
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Resolution (bits): 12bit
• Input Channel Type: Serial
• Supply Voltage Range - Analog: 2.7V To 5.5V
• Supply Current: 350µA
• Digital Ic Case Style: MSOP
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

6.5.1.2
When calibrating a set point or threshold of a sensor,
typically only a small portion of the DAC output range is
utilized. If the LSb size is adequate enough to meet the
application’s accuracy needs, the unused range 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.
EXAMPLE 6-2:
 2010 Microchip Technology Inc.
(a) Single Output DAC:
(b) Dual Output DAC:
V OUT
D
Thevenin
Equivalent
G
N
n
=
=
=
=
=
=
2.048 G
Gain selection (1x or 2x)
Digital value of DAC (0-255) for MCP4801/MCP4802
Digital value of DAC (0-1023) for MCP4811/MCP4812
Digital value of DAC (0-4095) for MCP4821/MCP4822
DAC bit resolution
Building a “Window” DAC
MCP4801
MCP4811
MCP4821
MCP4802
MCP4812
MCP4822

SPI

SINGLE-SUPPLY “WINDOW” DAC
R
V
V
D
------
2
23
23
trip
N
n
=
=
3-wire
=
------------------ -
R

------------------------------------------------------
V
R
V
-------------------------------------------- -
2
V
CC+
OUT
2
+
DD
R
DAC
R
3
R
R
3
R
R
1
2
2
23

+
+
+
+
R
R

23
V
V
3
23
V
CC-
OUT
R
1
R
3

R
1
R
R
2
3
V
V
CC+
V
CC-
OUT
If the threshold is not near V
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
MCP4801/4811/4821
R
SENSE
R
and
1
V
23
pull-down
illustrate this concept.
R
23
V
0.1 µF
O
V
TRIP
resistor.
REF
, 2V
Comparator
Example 6-2
DS22244B-page 27
REF
V
V
CC+
CC-
or V
SS
, then
and