Rainbow-electronics MAX5302 Bedienungsanleitung PDF herunterladen (Seite 10)

MAX5302

Low-Power, 12-Bit Voltage-Output DAC

with Serial Interface

10 ______________________________________________________________________________________

DAC

OUT

V+

+5V

V-

R1 = R2 = 10kΩ ±0.1%

REF

OUT

MAX5302

GND

Figure 10. Bipolar Output Circuit

Digitally Programmable Current Source

The circuit of Figure 12 places an NPN transistor (2N3904

or similar) within the op amp feedback loop to implement

a digitally programmable, unidirectional current source.

The output current is calculated with the following

equation:

OUT

= (V

REF

/ R) (NB / 4096)

where NB is the numeric value of the DAC’s binary input

code, and R is the sense resistor shown in Figure 12.

Power-Supply Considerations

On power-up, the input and DAC registers are cleared

(set to zero code).

For rated MAX5302 performance, V

REF

must be at least

1.4V below V

. Bypass V

with a 4.7µF capacitor in

parallel with a 0.1µF capacitor to GND. Use short lead

lengths and place the bypass capacitors as close to

the supply pins as possible.

Grounding and Layout Considerations

Digital or AC transient signals on GND can create noise

at the analog output. Connect GND to the highest-quality

ground available.

Good PC board ground layout minimizes crosstalk

between the DAC output, reference input, and digital

input. Reduce crosstalk by keeping analog lines away

from digital lines. Wire-wrapped boards are not recom-

mended.

Table 3. Bipolar Code Table

MAX5302

DAC

REF

OUT

10k

GND

+5V

Figure 9. Unipolar Rail-to-Rail Output Circuit

ANALOG OUTPUT

1111 1111 1111 (0)

1000 0000 0001 (0)

DAC CONTENTS

MSB LSB

1000 0000 0000 (0) 0V

0111 1111 1111 (0)

0000 0000 0000 (0)

0000 0000 0001 (0)

2047

2048

REF













2048

REF













-V

2048

REF













-V

2047

2048

REF













-V

2048

-V

REF REF













Note: ( ) are for sub-bit.

1 2 ... 5 6 7 8 9 10 11 12

Kommentare zu diesen Handbüchern

Keine Kommentare

Rainbow-electronics MAX5302 Bedienungsanleitung Seite 10

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Sensoren Rainbow-electronics MAX5302