MCP4921-E/P Microchip Technology Inc., MCP4921-E/P Datasheet - Page 24

• Manufacturer Part Number: MCP4921-E/P
• Description: SINGLE 12-BIT DAC WITH SPI INTERACE
• Manufacturer: Microchip Technology Inc.

Specifications of MCP4921-E/P

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

MCP4921/4922
6.6
In some applications, precision digital control of the
output range is desirable. Example 6-4 illustrates how
to use the MCP4922 to achieve this in a bipolar or
single-supply application.
EXAMPLE 6-4:
DS21897A-page 24
Thevenin
Equivalent
Selectable Gain and Offset Bipolar
Voltage Output Using A Dual DAC
SPI™
V
V
V
REFB
REFA
OUTB
V
V
IN+
V
V
IN+
O
45
3
MCP492X
MCP492X
Bipolar Voltage Source With Selectable Gain and Offset.
=
=
=
V
V
=
=
Offset Adjust Gain Adjust
DD
DD
V
V
----------------------------------------------- -
V
V
---------------------------------------------- -
V
------------------------------------------- -
OUTB
IN+
REFB
CC+
OUTB


R
1
R
R
R
R
DAC
DAC
G
3
+
4
3
R
4
4
+
B
+
+
R
----- -
R
45
+
+
R
2
1
V
V
R
R
-------
2
D
V
V


+
A
B
4
Bipolar “Window” DAC using R
12
5
45
OUTA
OUTB
CC-
B
CC-
–
V
(Gain Adjust)
(Offset Adjust)
V
45
R
R
OUTA
R
5
3
3
R
R


1
3
R
----- -
R
2
1


R
V
V
45
O
OUTA
V
V
=
=
CC
CC
Offset Adjust Gain Adjust
------------------
R
V
R
R
–
+
R
4
IN+
=
4
5
4
+
R


R
V
5
1
This circuit is typically used in Multiplier mode and is
ideal for linearizing a sensor whose slope and offset
varies. Refer to Section 6.9 “Using Multiplier Mode”
for more information on Multiplier mode.
The equation to design a bipolar “window” DAC would
be utilized if R
0.1uF
5
REFA
+
R
----- -
R
2
1
G


A
–
4
V
-------
2
D
and R
12
OUTA
A
V
V
3
CC
G = Gain select (1x or 2x)
R
CC
D = Digital value of DAC (0 – 4096)
, R
AV
5


2
R
----- -
R
+
–
4
SS
2
1


and R
= GND
 2004 Microchip Technology Inc.
5
are populated.
V
O