MCP4922-E/P Microchip Technology, MCP4922-E/P Datasheet - Page 28

• Manufacturer Part Number: MCP4922-E/P
• Description: IC DAC 12BIT DUAL W/SPI 14DIP
• Manufacturer: Microchip Technology

Specifications of MCP4922-E/P

• Number Of Converters: 2
• Package / Case: 14-DIP (0.300", 7.62mm)
• Settling Time: 4.5µs
• Number Of Bits: 12
• Data Interface: Serial, SPI™
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Resolution: 12 bit
• Interface Type: Serial (3-Wire, SPI, Microwire)
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.7 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

MCP4902/4912/4922
6.4
The MCP4902/4912/4922 family of devices are rail-to-
rail voltage output DAC devices designed to operate
with a V
robust enough to drive small-signal loads directly.
Therefore, it does not require any external output buffer
for most applications.
6.4.1
A common application for the DAC devices is
digitally-controlled set points and/or calibration of
variable parameters, such as sensor offset or slope.
For example, the MCP4922 provides 4096 output
steps. If the external voltage reference (V
4.096V, the LSb size is 1 mV. If a smaller output step
size is desired, a lower external voltage reference is
needed.
EXAMPLE 6-1:
DS22250A-page 28
(b) Dual Output DAC:
(a) Single Output DAC:
DD
Single-Supply Operation
range of 2.7V to 5.5V. Its output amplifier is
DC SET POINT OR CALIBRATION
SPI
V
REF
V OUT
V trip
3-wire
EXAMPLE CIRCUIT OF SET POINT OR THRESHOLD CALIBRATION
MCP4912
MCP4922
MCP4902
MCP4901
MCP4911
MCP4921
=
=
V
V
V OUT
DD
DAC
REF




G
--------------------
R 1

D
------
2
R 2
+
V
N
n
OUT
R 2



REF
R
1
) is
R
D
N = DAC Bit Resolution
G = Gain selection (1x or 2x)
2
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
R
SENSE
6.4.1.1
If the application is calibrating the bias voltage of a
diode or transistor, a bias voltage range of 0.8V may be
desired with about 200 µV resolution per step. Two
common methods to achieve a 0.8V range is to either
reduce V
DAC’s output.
Using a V
the
occasionally, when using a low-voltage V
floor causes SNR error that is intolerable. Using a
voltage divider method is another option and provides
some advantages when V
when the desired output voltage is not available. In this
case, a larger value V
scale the output range down to the precise desired
level.
Example 6-1
bypass capacitor on the output of the voltage divider
plays a critical function in attenuating the output noise
of the DAC and the induced noise from the
environment.
V
DD
desired
REF
REF
0.1 uF
Decreasing Output Step Size
to 0.82V or use a voltage divider on the
illustrates this concept. Note that the
is an option if the V
output
V
TRIP
REF
 2010 Microchip Technology Inc.
voltage
Comparator
REF
is used while two resistors
needs to be very low or
V
V
CC
CC
REF
+
–
range.
is available with
REF
, the noise
However,
V
O