MCP4821-E/SN Microchip Technology, MCP4821-E/SN Datasheet - Page 26

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

Specifications of MCP4821-E/SN

• Number Of Converters: 1
• Package / Case: 8-SOIC (3.9mm Width)
• 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: Surface Mount
• 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: SMD/SMT
• 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

MCP4801/4811/4821
6.5
The MCP4801/4811/4821 devices are rail-to-rail
voltage output DAC devices designed to operate with a
V
enough to drive small-signal loads directly. Therefore, it
does not require any external output buffer for most
applications.
6.5.1
A common application for the devices is a digitally-
controlled set point and/or calibration of variable
parameters, such as sensor offset or slope. For
example, the MCP4821 and MCP4822 provide
4096 output steps. If G = 1x is selected, the internal
2.048V V
G = 2x is selected, the internal 2.048 V
produce 1 mV of resolution.
EXAMPLE 6-1:
DS22244B-page 26
DD
(a) Single Output DAC:
(b) Dual Output DAC:
range of 2.7V to 5.5V. Its output amplifier is robust
Single-Supply Operation
REF
DC SET POINT OR CALIBRATION
would produce 500 µV of resolution. If
MCP4801
MCP4811
MCP4821
MCP4802
MCP4812
MCP4822
V OUT
V trip
EXAMPLE CIRCUIT OF SET POINT OR THRESHOLD CALIBRATION
SPI
=
=
2.048 G
V OUT
3-wire




V
--------------------
R 1

DD
DAC
D
------
2
R 2
+
N
n
R 2



REF
V
would
OUT
D
G
N
n
R
1
=
=
=
=
=
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
R
R
6.5.1.1
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 are to either
reduce V
device that uses external reference) or use a voltage
divider on the 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.
SENSE
2
desired
V
DD
REF
REF
Decreasing Output Step Size
illustrates this concept. Note that the
is an option if the V
to 0.82V (using the MCP49XX family
0.1 µF
output
REF
V
 2010 Microchip Technology Inc.
TRIP
voltage
REF
is used while two resistors
needs to be very low or
Comparator
REF
V
V
range.
CC
CC
is available with
+
–
REF
, the noise
However,