MCP4821-E/SN Microchip Technology, MCP4821-E/SN Datasheet - Page 20

• 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

MCP4821/MCP4822
6.5
The MCP482X devices are Rail-to-Rail (R-R) input and
output DACs designed to operate with a V
2.7V to 5.5V. Its output amplifier is robust enough to
drive common, small-signal loads directly, thus eliminat-
ing the cost and size of an external buffer for most
applications.
6.5.1
A common application for a DAC with the MCP482X
family’s performance is a digitally-controlled set point
and/or calibration of variable parameters, such as sen-
sor offset or slope. 12-bit resolution provides 4096 out-
put steps. If G = 1 is selected, then the internal 2.048
V
selected, the internal 2.048 V
of resolution.
EXAMPLE 6-1:
DS21953A-page 20
REF
would produce 500 µV of resolution. If G = 2 is
SPI™
Single-Supply Operation
DC SET POINT OR CALIBRATION
3
MCP482X
V
DD
Set Point or Threshold Calibration.
V OUT
V trip
REF
V
would produce 1 mV
=
OUT
=
2.048 G
V OUT
R
DD
⎛
⎜
⎝
1
--------------------
R 1
-------- -
2
range of
D
12
R 2
+
R
2
R 2
⎞
⎟
⎠
R
SENSE
V
DD
6.5.1.1
If the application is calibrating the threshold of a diode,
transistor or resistor tied to AV
0.8V may be desired to provide 200 µV resolution. Two
common methods to achieve a 0.8V range is to either
reduce V
and external voltage reference) or use a voltage divider
on the DAC’s output. Typically, when using a low-
voltage V
intolerable. The voltage divider method provides some
advantages when V
the desired output voltage is not available. Using two
resistors to scale the output range down to the precise
desired level is a simple, low-cost method to achieve
very small step sizes. Example 6-1 illustrates this
concept. Note that the 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.
The MCP482X family’s low ±0.75 (max.) DNL
performance is critical to meeting calibration accuracy
in production.
0.1 uF
REF
REF
G = Gain select (1x or 2x)
D = Digital value of DAC (0 – 4096)
, the noise floor causes SNR error that is
to 0.82V (would require MCP492X device
V
Decreasing The Output Step Size
TRIP
REF
Comparator
© 2005 Microchip Technology Inc.
needs to be very low or when
V
V
CC
CC
+
–
SS
, a threshold range of