MCP4725 datasheet(31/42 Pages) MICROCHIP

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DS22039C-page 31

MCP4725

8.5.4

BIPOLAR OPERATION

Bipolar operation is achievable using the MCP4725 by

using an external operational amplifier (op amp). This

allows a general purpose DAC, with its cost and

availability advantages, to meet almost any desired

output voltage range, power and noise performance.

Example 8-3 illustrates a simple bipolar voltage source

configuration. R1 and R2 allow the gain to be selected,

while R3 and R4 shift the DAC's output to a selected

offset. Note that R4 can be tied to VDD (= VREF) instead

of VSS, if a higher offset is desired. Note that a pull-up

to VDD could be used, instead of R4, if a higher offset is

desired.

EXAMPLE 8-3:

Digitally-Controlled Bipolar Voltage Source.

VDD

VOUT

VIN+

0.1 µF

VCC+

VCC–

IN+

OUTR4

--------------------

IN+ 1

------

⎝⎠

⎛⎞

------

⎝⎠

⎛⎞

–

To MCU

(MASTER)

R R

MCP4725

VDD

VOUT

SCL

VSS

VDD

SDA

10 µF

0.1 µF

VDD

where D = DAC Input Code (0 – 4095)

OUT

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