Low-Cost, Triple, 8-Bit Voltage-Output DACs

with Serial Interface

12

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Applications Information

Power-Supply and Reference

Operating Ranges

The MAX512 is fully specified to operate with

2.7V to 3.6V, covering all commonly used supply voltages

in 3V systems. The MAX512/MAX513 can also be used

with a negative supply ranging from -1.5V to -5.5V. Using a

negative supply typically improves zero-code error and

settling time (as shown in the

Typical Operating

Characteristics graphs).

The two separate reference inputs for the DAC pair A/B

and the unbuffered output C allow different full-scale out-

put voltages and, if a negative supply is used, also allow

different polarity. In dual-supply mode, REFAB can vary

Power-supply sequencing is not critical. If a negative sup-

ground. Do not apply signals to the digital inputs until the

device is powered-up. If this is not possible, add current-

limiting resistors to the digital inputs.

Power-Supply Bypassing and

Ground Management

should be connected to the highest quality ground

0.1µF to 0.22µF capacitor to GND. Reference inputs

can be used without bypassing. For optimum line/load-

transient response and noise performance, bypass the

reference inputs with 0.1µF to 4.7µF to GND. Careful

PC board layout minimizes crosstalk among DAC out-

puts, reference inputs, and digital inputs. Separate ana-

log lines with ground traces between them. Make sure

that high-frequency digital lines are not routed in paral-

lel to analog lines.

Unipolar Output

With unipolar output, the output voltage and the refer-

ence voltage are the same polarity. The MAX512/

MAX513 can be used with a single supply if the refer-

ence voltages are positive. With a negative supply,

t h e

REFAB

voltage

can

vary

from

tiplication.

CS

SCLK

DIN

LOUT

Figure 3. MAX512/MAX513 Detailed Serial-Interface Timing Diagram