MP7226KS 查看數據表（PDF） - Exar Corporation

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MP7226KS

BiCMOS Fixed, Quad, Voltage Output, Single or Dual Supply 8-Bit Digital-to-Analog Converter

Exar Corporation 

MP7226

VREF

VREF

–

DAC

+

R1

R2

–

VOUT +

Bipolar Binary Operation

VOUT

The Bipolar Mode configuration for each DAC requires one

external op-amp and two resistors per channel.

Figure 5. shows a typical Bipolar Operation circuit using the

MP7226. Table 3. shows the code relationship for the circuit of

Figure 5. assuming R1 = R2 .

AC Reference Signal

VSS

AGND

VOUT = Dn X VREF X (1+R2/R1) – VREF X R2/R1

if R1 = R2

VOUT = VREF X (2Dn – 1)

Where Dn is the digital input code and can vary from 0 to 255

Figure 5. Bipolar Output Circuit

+15 V

+4 V

AC

Reference

R1

C

+

Input

R2

–

–4 V

An AC signal can be applied to the reference of the MP7226

for multiplying capability within the upper (+10V) and lower

(+2V) limits of the reference voltage input, with either single or

dual supplies . This signal must be level shifted or AC coupled

with proper bias level before being applied to the reference in-

put. Figure 6. shows techniques for applying an AC signal to the

MP7226. Since all four DACs share a common reference, they

will all share this AC modulated reference. Input frequencies up

to 50kHz will typically be distorted less than 0.1% .

+10 V

DC

Offset

+2 V

VREF

VDD

–

DAC

+

VOUT

DCOFFSET = VDD (+15) X R2/R1+R2

VSS

–5 V or GND

AGND

Figure 6. AC Reference Input Signal Circuit (AC Couple)

Rev. 2.00

10

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