Datasheet
2010 Microchip Technology Inc. DS22249A-page 17
MCP4802/4812/4822
4.0 GENERAL OVERVIEW
The MCP4802, MCP4812 and MCP4822 are dual
voltage output 8-bit, 10-bit and 12-bit DAC devices,
respectively. These devices include rail-to-rail output
amplifiers, internal voltage reference, shutdown and
reset-management circuitry. The devices use an SPI
serial communication interface and operate with a sin-
gle 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:
• MCP4802 (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.
• MCP4812 (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.
• MCP4822 (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 for these devices is
the maximum deviation between an actual code transi-
tion point and its corresponding ideal transition point
once offset and gain errors have been removed. The
two end points 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)
earlier 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 MCP4802
= 10 for MCP4812
= 12 for MCP4822
TABLE 4-1: LSb OF EACH DEVICE
Device
Gain
Selection
LSb Size
MCP4802
(n = 8)
1x 2.048V/256 = 8 mV
2x 4.096V/256 = 16 mV
MCP4812
(n = 10)
1x 2.048V/1024 = 2 mV
2x 4.096V/1024 = 4 mV
MCP4822
(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