Rainbow Electronics MAX5259 User Manual

Page 17

Power Sequencing

The voltage applied to REF should not exceed V

any time. If proper power sequencing is not possible,
connect an external Schottky diode between REF and
V

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

Bypass V

with a 0.1µF capacitor, located as close to

and GND as possible. Careful PC board layout

minimizes crosstalk among DAC outputs and digital
inputs. Figure 10 shows suggested 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
MAX5258/MAX5259 unipolar configuration, and Table 2
shows the unipolar code.

MAX5258/MAX5259

+3V/+5V, Low-Power, 8-Bit Octal DAC

with Rail-to-Rail Output Buffers

______________________________________________________________________________________

REF

R15

R16

R255

DAC A

MSB DECODER

LSB DECODER

Figure 8. DAC Simplified Circuit Diagram

OUTC

OUTD

DOUT

DIN

SYSTEM GND

OUTB

OUTA

GND

REF

LDAC

Figure 10. Suggested PC Board Layout for Minimizing
Crosstalk (Bottom View)

DAC CODE

NEGATIVE

OFFSET

OUTPUT

VOLTAGE

Figure 9. Effect of Negative Offset (Single Supply)