Rainbow Electronics MAX5531 - Manual (Page 17)

MAX5530/MAX5531
Ultra-Low-Power, 12-Bit,
Voltage-Output DACs
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R
2N3904
N
DAC
IS THE NUMERIC VALUE OF THE DAC INPUT CODE.
I
LED
REFIN
LED
MAX5530
V+
DAC
VOUT
I LED =
V REFIN × N DAC
4096 × R
FB
Figure 4. Programmable Current Source Driving an LED
DAC
BAND
GAP
TO ADC
OUT
REFOUT
MAX5531
TO ADC
TO ADC
FB
WE
SENSOR
CE
I F R F
C L
REF
Figure 6. Self-Biased Two-Electrode Potentiostat Application
R
FB
N
DAC
IS THE NUMERIC VALUE
OF THE DAC INPUT CODE.
I
T
REFIN
MAX5530
VOUT
V OUT = V BIAS + (I T × R)
V
OUT
V
BIAS
TRANSDUCER
V BIAS =
V REFIN × N DAC
4096
DAC
Figure 5. Transimpedance Configuration for a Voltage-Biased
Current-Output Transducer
N A IS THE DAC INPUT CODE
(0 TO 4095 DECIMAL).
REFIN
MAX5530
OUT
FB
V OUT =
V
REFIN
× N
A
4096
DAC
Figure 7. Unipolar Output Circuit
DAC CONTENTS
MSB LSB
ANALOG OUTPUT
1111 1111 1100 +V REF (4095/4096)
1000 0000 0001 +V REF (2049/4096)
1000 0000 0000 +V REF (2048/4096) = +V REF / 2
0111 1111 1111 +V REF (2047/4096)
0000 0001 0001 +V REF (1/4096)
0000 0000 0000 0V
Table 4. Unipolar Code Table (Gain = +1)
DAC CONTENTS
MSB LSB
ANALOG OUTPUT
1111 1111 1111 +V REF (2047/2048)
1000 0000 0001 +V REF (1/2048)
1000 0000 0000 0V
0111 1111 1111 -V REF (1/2048)
0000 0000 0001 -V REF (2047/2048)
0000 0000 0000 -V REF (2048/2048) = -V REF
Table 5. Bipolar Code Table (Gain = +1)