MAX535/MAX5351
Low-Power, 13-Bit Voltage-Output DACs
with Serial Interface
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The MAX535’s total harmonic distortion plus noise (THD
+ N) is typically less than -77dB (full-scale code), and
the MAX5351’s THD + N is typically less than -72dB
(full-scale code), given a 1Vp-p signal swing and input
frequencies up to 25kHz. The typical -3dB frequency is
650kHz for both devices, as shown in the
Typical
Operating Characteristics
graphs.
Digitally Programmable Current Source
The circuit of Figure 12 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:
I
OUT
= (V
REF
/ R) x (NB / 8192)
where NB is the numeric value of the DAC’s binary
input code and R is the sense resistor shown in
Figure 12.
MAX535
MAX5351
DAC
REF
OUT
FB
GND
+5V/+3.3V
V
DD
Figure 8. Unipolar Output Circuit
Table 3. Bipolar Code Table
MAX535
MAX5351
DAC
REF
OUT
10k
10k
GND
+5V/+3.3V
V
DD
FB
Figure 9. Unipolar Rail-to-Rail Output Circuit
ANALOG OUTPUT
11111 1111 1111
10000 0000 0001
DAC CONTENTS
MSB LSB
10000 0000 0000 0V
01111 1111 1111
00000 0000 0000
00000 0000 0001
+V
4095
4096
REF
+V
1
4096
REF
-V
1
4096
REF
-V
4095
4096
REF
-V
4096
4096
-V
REF REF
=
