Data Sheet
Table Of Contents
- 1.0 Electrical Characteristics
- 2.0 Typical Performance Curves
- Figure 2-1: DNL vs. Code.
- Figure 2-2: DNL vs. Code and Ambient Temperature.
- Figure 2-3: Absolute DNL vs. Ambient Temperature.
- Figure 2-4: INL vs. Code and Ambient Temperature.
- Figure 2-5: Absolute INL vs. Ambient Temperature.
- Figure 2-6: INL vs. Code.
- Figure 2-7: Full-Scale VOUTA w/G = 1 (VREF) vs. Ambient Temperature and VDD.
- Figure 2-8: Full-Scale VOUTA w/G = 2 (2VREF) vs.Ambient Temperature and VDD.
- Figure 2-9: Output Noise Voltage Density (VREF Noise Density w/G = 1) vs. Frequency.
- Figure 2-10: Output Noise Voltage (VREF Noise Voltage w/G = 1) vs. Bandwidth.
- Figure 2-11: MCP4821 IDD vs. Ambient Temperature and VDD.
- Figure 2-12: MCP4821 IDD Histogram (VDD = 2.7V).
- Figure 2-13: MCP4821 IDD Histogram (VDD = 5.0V).
- Figure 2-14: MCP4822 IDD vs. Ambient Temperature and VDD.
- Figure 2-15: MCP4822 IDD Histogram (VDD = 2.7V).
- Figure 2-16: MCP4822 IDD Histogram (VDD = 5.0V).
- Figure 2-17: Hardware Shutdown Current vs. Ambient Temperature and VDD.
- Figure 2-18: Software Shutdown Current vs. Ambient Temperature and VDD.
- Figure 2-19: Offset Error vs. Ambient Temperature and VDD.
- Figure 2-20: Gain Error vs. Ambient Temperature and VDD.
- Figure 2-21: VIN High Threshold vs. Ambient Temperature and VDD.
- Figure 2-22: VIN Low Threshold vs. Ambient Temperature and VDD.
- Figure 2-23: Input Hysteresis vs. Ambient Temperature and VDD.
- Figure 2-24: VOUT High Limit vs. Ambient Temperature and VDD.
- Figure 2-25: VOUT Low Limit vs. Ambient Temperature and VDD.
- Figure 2-26: IOUT High Short vs. Ambient Temperature and VDD.
- Figure 2-27: IOUT vs. VOUT. Gain = 2.
- Figure 2-28: VOUT Rise Time 100%.
- Figure 2-29: VOUT Fall Time.
- Figure 2-30: VOUT Rise Time 50%.
- Figure 2-31: VOUT Rise Time 25% - 75%.
- Figure 2-32: VOUT Rise Time Exit Shutdown.
- Figure 2-33: PSRR vs. Frequency.
- 3.0 Pin descriptions
- 4.0 General Overview
- 5.0 Serial Interface
- 6.0 Typical Applications
- 6.1 Digital Interface
- 6.2 Power Supply Considerations
- 6.3 Output Noise Considerations
- 6.4 Layout Considerations
- 6.5 Single-Supply Operation
- 6.6 Bipolar Operation
- 6.7 Selectable Gain and Offset Bipolar Voltage Output Using A Dual DAC
- 6.8 Designing A Double-Precision DAC Using A Dual DAC
- 6.9 Building A Programmable Current Source
- 7.0 Development support
- 8.0 Packaging Information
MCP4821/MCP4822
DS21953A-page 20 © 2005 Microchip Technology Inc.
6.5 Single-Supply Operation
The MCP482X devices are Rail-to-Rail (R-R) input and
output DACs designed to operate with a V
DD
range of
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 DC SET POINT OR CALIBRATION
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
REF
would produce 500 µV of resolution. If G = 2 is
selected, the internal 2.048 V
REF
would produce 1 mV
of resolution.
6.5.1.1 Decreasing The Output Step Size
If the application is calibrating the threshold of a diode,
transistor or resistor tied to AV
SS
, a threshold range of
0.8V may be desired to provide 200 µV resolution. Two
common methods to achieve a 0.8V range is to either
reduce V
REF
to 0.82V (would require MCP492X device
and external voltage reference) or use a voltage divider
on the DAC’s output. Typically, when using a low-
voltage V
REF
, the noise floor causes SNR error that is
intolerable. The voltage divider method provides some
advantages when V
REF
needs to be very low or when
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.
EXAMPLE 6-1: Set Point or Threshold Calibration.
MCP482X
V
DD
SPI™
3
V
TRIP
R
1
R
2
0.1 uF
Comparator
G = Gain select (1x or 2x)
D = Digital value of DAC (0 – 4096)
V
OUT
2.048 G
D
2
12
---------
⋅
=
V
CC
+
V
CC
–
V
OUT
V
trip
V
OUT
R
2
R
1
R
2
+
--------------------
⎝⎠
⎜⎟
⎛⎞
=
V
DD
R
SENSE