Datasheet
2010 Microchip Technology Inc. DS22244B-page 17
MCP4801/4811/4821
4.0 GENERAL OVERVIEW
The MCP4801, MCP4811 and MCP4821 are single
channel voltage-output 8-bit, 10-bit and 12-bit DAC
devices, respectively. These devices include rail-to-rail
output amplifier, internal voltage reference, shutdown
and reset-management circuitry. The devices use an
SPI serial communication interface and operate with a
single supply voltage from 2.7V to 5.5V.
The DAC input coding of these devices is straight
binary. Equation 4-1 shows the DAC analog output
voltage calculation.
EQUATION 4-1: ANALOG OUTPUT
VOLTAGE (V
OUT
)
The ideal output range of each device is:
• MCP4801 (n = 8)
(a) 0.0V to 255/256 * 2.048V when gain setting = 1x.
(b) 0.0V to 255/256 * 4.096V when gain setting = 2x.
•MCP4811 (n = 10)
(a) 0.0V to 1023/1024 * 2.048V when gain setting = 1x.
(b) 0.0V to 1023/1024 * 4.096V when gain setting = 2x.
• MCP4821 (n = 12)
(a) 0.0V to 4095/4096 * 2.048V when gain setting = 1x.
(b) 0.0V to 4095/4096 * 4.096V when gain setting = 2x.
1 LSb is the ideal voltage difference between two
successive codes. Table 4-1 illustrates the LSb
calculation of each device.
4.0.1 INL ACCURACY
Integral Non-Linearity (INL) error is the maximum
deviation between an actual code transition point and
its corresponding ideal transition point once offset and
gain errors have been removed. The two endpoints
method (from 0x000 to 0xFFF) is used for the
calculation. Figure 4-1 shows the details.
A positive INL error represents transition(s) later than
ideal. A negative INL error represents transition(s) ear-
lier than ideal.
FIGURE 4-1: Example for INL Error.
Note:
See the output swing voltage specification in
Section 1.0 “Electrical Characteristics”
.
V
OUT
2.048V D
n
2
n
----------------------------------- G=
Where:
2.048V = Internal voltage reference
D
n
= DAC input code
G = Gain selection
=2 for <GA
> bit = 0
=1 for <GA> bit = 1
n = DAC Resolution
=8 for MCP4801
=10 for MCP4811
= 12 for MCP4821
TABLE 4-1: LSb OF EACH DEVICE
Device
Gain
Selection
LSb Size
MCP4801
(n = 8)
1x 2.048V/256 = 8 mV
2x 4.096V/256 = 16 mV
MCP4811
(n = 10)
1x 2.048V/1024 = 2 mV
2x 4.096V/1024 = 4 mV
MCP4821
(n = 12)
1x 2.048V/4096 = 0.5 mV
2x 4.096V/4096 = 1 mV
111
110
101
100
011
010
001
000
Digital
Input
Code
Actual
Transfer
Function
INL < 0
Ideal Transfer
Function
INL < 0
DAC Output