MCP4912-E/ST Microchip Technology, MCP4912-E/ST Datasheet - Page 29

• Manufacturer Part Number: MCP4912-E/ST
• Description: DAC 10BIT DUAL W/SPI 14TSSOP
• Manufacturer: Microchip Technology

Specifications of MCP4912-E/ST

• Number Of Converters: 2
• Settling Time: 4.5µs
• Package / Case: 14-TSSOP
• Number Of Bits: 10
• Data Interface: Serial, SPI™
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Number Of Dac Outputs: 2
• Resolution: 10 bit
• Interface Type: SPI
• Supply Voltage (max): 6.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 55 C
• Supply Current: 350 uA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

6.4.1.2
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:
D
V OUT
G = Gain selection (1x or 2x)
N = DAC Bit Resolution
Thevenin
Equivalent
n
= Digital value of DAC (0-4095) for MCP4921/MCP4922
= Digital value of DAC (0-255) for MCP4901/MCP4902
= Digital value of DAC (0-1023) for MCP4911/MCP4912
=
Building a “Window” DAC
V
REF
SPI
V

REF
G
MCP4902
MCP4912
MCP4922
MCP4921
MCP4901
MCP4911
SINGLE-SUPPLY “WINDOW” DAC
R
V
V

3
23
23
trip
D
------
2
N
n
=
=
V
=
------------------
R

---------------------------------------------------- -
DD
DAC
V
R
V
------------------------------------------- -
2
CC+
2
OUT
+
R
R
3
R
R
3
R
R
2
2
2
23

+
+
+
+
R
V
R

23
V
OUT
V
3
23
CC-
R
R
1
3
R

1
R
R
3
2
V
V
CC+
CC-
V
OUT
If the threshold is not near V
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 and pull-down resistor.
Example 6-4
R
sense
MCP4902/4912/4922
R
1
V
23
illustrate this concept.
R
0.1 µF
V
23
V
trip
O
REF
Comparator
or V
V
V
CC+
CC-
Example 6-2
DS22250A-page 29
SS
, then creating
and