MAX5104 データシートの表示（PDF） - Maxim Integrated
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MAX5104 Datasheet PDF : 12 Pages
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Low-Power, Dual, Voltage-Output, 12-Bit DAC
with Serial Interface
VOUT = VREF [((2 · NB) / 4096) - 1]
where NB represents the numeric value of the DAC’s
binary input code. Table 3 shows digital codes and the
corresponding output voltage for Figure 11’s circuit.
Using an AC Reference
In applications where the reference has an AC signal
component, the MAX5104 has multiplying capabilities
within the reference input voltage range specifications.
Figure 12 shows a technique for applying a sinusoidal
input to REF_, where the AC signal is offset before
being applied to the reference input.
Harmonic Distortion and Noise
The total harmonic distortion plus noise (THD+N) is typ-
ically less than -78dB at full scale with a 1Vp-p input
swing at 5kHz.
Digital Calibration and
Threshold Selection
Figure 13 shows the MAX5104 in a digital calibration
application. With a bright-light value applied to the pho-
todiode (on), the DAC is digitally ramped until it trips
the comparator. The microprocessor (µP) stores this
“high” calibration value. Repeat the process with a dim
light (off) to obtain the dark current calibration.
Table 3. Bipolar Code Table
DAC CONTENTS
MSB
LSB
ANALOG OUTPUT
1111 1111 1 111 (0)
+VREF
2047
2048
1000 0000 0 001 (0)
1000 0000 0 000 (0)
+VREF
1
2048
0V
0111 1111 1 111 (0)
-VREF
1
2048
0000 0000 0 001 (0)
+VREF
2047
4096
⋅
2
0000 0000 0 000 (0)
-VREF
2048
2048
= - VREF
Note: ( ) are for the sub-bit.
REF_
+5V/+3V
10k
10k
OS_
VDD
R
V+
MAX5104
R
10k
VOUT
DAC _
OUT_
DGND AGND
10k
V-
+5V/
+3V
AC 26k
REFERENCE
INPUT
+5V/+3V
MAX495
500mVp-p
10k
REF
DAC_
VDD
R
OS_
R
OUT_
MAX5104
AGND
DGND
Figure 12. AC Reference Input Circuit
REF_
+5V/+3V
VDD
R
MAX5104
R
µP
DIN
DAC _
AGND
DGND
V+
PHOTODIODE
OS_
OUT_
V+
VOUT
V-
RPULLDOWN
Figure 11. Bipolar Output Circuit
Figure 13. Digital Calibration
______________________________________________________________________________________ 11
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