MAX533
2.7V, Low-Power, 8-Bit Quad DAC
with Rail-to-Rail Output Buffers
______________________________________________________________________________________ 13
CS
LDAC
SCLK
DIN
MAX533
CS
LDAC
SCLK
DIN
MAX533
CS
LDAC
SCLK
DIN
MAX533
TO OTHER
SERIAL
DEVICES
DIN
SCLK
LDAC
CS1
CS2
CS3
Figure 7. Multiple MAX533s sharing one DIN line. Simultaneously update by strobing LDAC, or specifically update by enabling an
individual CS.
Output Buffer Amplifiers
All MAX533 voltage outputs are internally buffered by
precision unity-gain followers that slew at about
0.6V/µs. The outputs can swing from GND to V
DD
. With
a 0V to +2.5V (or +2.5V to 0V) output transition, the
amplifier outputs will typically settle to 1/2LSB in 6µs
when loaded with 10kin parallel with 100pF.
The buffer amplifiers are stable with any combination of
resistive (10k) or capacitive loads.
__________Applications Information
DAC Linearity and Voltage Offset
The output buffer can have a negative input offset volt-
age that would normally drive the output negative, but
since there is no negative supply the output stays at 0V
(Figure 9). When linearity is determined using the end-
point method, it is measured between zero code (all
inputs 0) and full-scale code (all inputs 1) after offset
and gain error are calibrated out. However, in single-
supply operation the next code after zero may not
change the output (Figure 9), so the lowest code that
produces a positive output is the lower endpoint.
MAX533
Power Sequencing
The voltage applied to REF should not exceed V
DD
at
any time. If proper power sequencing is not possible,
connect an external Schottky diode between REF and
V
DD
to ensure compliance with the absolute maximum
ratings. Do not apply signals to the digital inputs before
the device is fully powered up.
Power-Supply Bypassing
and Ground Management
Connect AGND and DGND together at the IC. This
ground should then return to the highest-quality ground
available. Bypass V
DD
with a 0.1µF capacitor, located
as close to V
DD
and DGND as possible.
Careful PC board layout minimizes crosstalk among
DAC outputs and digital inputs. Figure 10 shows sug-
gested circuit board layout to minimize crosstalk.
Unipolar-Output,
Two-Quadrant Multiplication
In unipolar operation, the output voltages and the refer-
ence input are the same polarity. Figure 11 shows the
MAX533 unipolar configuration, and Table 2 shows the
unipolar code.
2.7V, Low-Power, 8-Bit Quad DAC
with Rail-to-Rail Output Buffers
14 ______________________________________________________________________________________
Table 2. Unipolar Code Table
1
Note: 1LSB = (V
REF
) (2
-8
) = +V
REF
(––––)
256
1
+V
REF
(––––)
256
0 0 0 10 0 0 0
0V0 0 0 00 0 0 0
127
+V
REF
(––––)
256
1 1 1 10 1 1 1
128
V
REF
+V
REF
(––––)= +
–––
256 2
0 0 0 01 0 0 0
129
+V
REF
(––––)
256
0 0 0 11 0 0 0
255
+V
REF
(––––)
256
1 1 1 11 1 1 1
ANALOG
OUTPUT
LSBMSB
DAC CONTENTS
DAC CODE
0V
NEGATIVE
OFFSET
OUTPUT
VOLTAGE
Figure 9. Effect of Negative Offset (Single Supply)
R1
R0
REF
D7
D5
D6
D4
R15
R16
R255
LSB DECODER
D2D3
DAC A
D1 D0
MSB DECODER
Figure 8. DAC Simplified Circuit Diagram
MAX533
2.7V, Low-Power, 8-Bit Quad DAC
with Rail-to-Rail Output Buffers
______________________________________________________________________________________ 15
_________________________________________________________Functional Diagram
MAX533
OUTA
DAC A
DAC B
DAC C
DAC D
REF
DAC
REGISTER A
DECODE
CONTROL
INPUT
REGISTER A
DAC
REGISTER B
INPUT
REGISTER B
DAC
REGISTER C
INPUT
REGISTER C
DAC
REGISTER D
INPUT
REGISTER D
12-BIT
SHIFT
REGISTER
SR
CONTROL
CS DIN
SCLK
OUTB
OUTC
OUTD
DOUT
LDAC
CLR
V
DD
PDE DGND AGND
UPO
OUTC
OUTD
AGND
OUTB
OUTA
REF
SYSTEM GND
Figure 10. Suggested PC Board Layout for Minimizing
Crosstalk (Bottom View)
DAC A
DAC B
DAC C
DAC D
REFAB
MAX533
OUTA
OUTB
OUTC
OUTD
SERIAL
INTERFACE
NOT SHOWN
REFERENCE INPUT
2
1
16
15
V
DD
+3V
313
14 12
AGND
DGND
Figure 11. Unipolar Output Circuit

MAX533AEPE

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
IC DAC QUAD LP +2.7V 8BIT 16-DIP
Lifecycle:
New from this manufacturer.
Delivery:
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