max5251aepp Maxim Integrated Products, Inc., max5251aepp Datasheet - Page 14

• Manufacturer Part Number: max5251aepp
• Description: Max5251 +3v, Quad, 10-bit Voltage-output Dac With Serial Interface
• Manufacturer: Maxim Integrated Products, Inc.

+3V, Quad, 10-Bit Voltage-Output DAC
with Serial Interface
Figure 10. Unipolar Rail-to-Rail Output Circuit
Figure 11. Bipolar Output Circuit
14
V
A
REF_
MAX5251
REFAB
V
______________________________________________________________________________________
= 1 +
DAC
= V
16k
10k
REFCD
= 2.6
REFAB
MAX5251
= 1.25V
REFERENCE INPUTS
DAC A
DAC B
DAC C
DAC D
R1
REFCD
AGND
OUT_
FB_
R1 = R2 = 10k ± 0.1%
V
DD
+3.3V
DGND
+3.3V
-3.3V
R2
FBA
OUTA
FBB
OUTB
FBC
OUTC
FBD
OUTD
16k
16k
16k
16k
10k
10k
10k
10k
V
OUT
In applications where the reference has AC signal com-
ponents, the MAX5251 has multiplying capability within
the reference input range specifications. Figure 12
shows a technique for applying a sine-wave signal to
the reference input where the AC signal is offset before
being applied to REFAB/REFCD. The reference voltage
must never be more negative than DGND.
The MAX5251’s total harmonic distortion plus noise
(THD + N) is typically less than -72dB (full-scale code),
given a 1V
25kHz. The typical -3dB frequency is 650kHz, as
shown in the Typical Operating Characteristics graphs.
The circuit of Figure 13 places an NPN transistor
(2N3904 or similar) within the op-amp feedback loop to
implement a digitally programmable, unidirectional cur-
rent source. This circuit can be used to drive 4–20mA
current loops, which are commonly used in industrial-
control applications. The output current is calculated
with the following equation:
where NB is the numeric value of the DAC’s binary
input code and R is the sense resistor shown in
Figure 13.
Figure 12. AC Reference Input Circuit
REFERENCE
500mV
+3.3V
INPUT
AC
Digitally Programmable Current Source
P-P
26k
P-P
I
signal swing and input frequencies up to
OUT
10k
= (V
REF
Using an AC Reference
DAC_
/ R) x (NB / 1024)
1/2 MAX492
REF_
AGND
MAX5251
V
DD
DGND
OUT_