Rainbow-electronics MAX5295 Bedienungsanleitung PDF herunterladen (Seite 28)

MAX5290–MAX5295

Buffered, Fast-Settling, Dual, 12-/10-/8-Bit,

Voltage-Output DACs

28 ______________________________________________________________________________________

Applications Information

Unipolar Output

Figure 7 shows the unity gain of the MAX5290 in a

unipolar output configuration. Table 24 lists the unipolar

output codes.

Bipolar Output

The MAX5290 outputs can be configured for bipolar

operation, as shown in Figure 8. The output voltage is

given by the following equation:

OUT_

= V

REF

x (CODE - 2048) / 2048

where CODE represents the numeric value of the

DAC’s binary input code (0 to 4095 decimal). Table 25

shows digital codes and the corresponding output volt-

age for the Figure 8 circuit.

Configurable Output Gain

The MAX5291/MAX5293/MAX5295 have force-sense out-

puts, which provide a connection directly to the inverting

terminal of the output op amp, yielding the most flexibility.

The advantage of the force-sense output is that specific

gains can be set externally for a given application. The

gain error for the MAX5291/MAX5293/MAX5295 is speci-

fied in a unity-gain configuration (op-amp output and

inverting terminals connected) and additional gain error

results from external resistor tolerances. The force-sense

DACs allow many useful circuits to be created with only a

few simple external components.

An example of a custom, fixed gain using the

MAX5291’s force-sense output is shown in Figure 9. In

this example, the external reference is set to 1.25V, and

the gain is set to +1.1V/V with external discrete resis-

tors to provide an approximate 0 to 1.375V DAC output

voltage range.

OUT_

= [(0.5 x V

REF

x CODE) / 4096] x [1 + (R2 / R1)]

where CODE represents the numeric value of the

DAC’s binary input code (0 to 4095 decimal).

In this example, if R2 = 12kΩ and R1 = 10kΩ, set the

gain = 1.1V/V:

OUT_

= [(0.5 x 1.25V x CODE) / 4096] x 2.2

Table 25. Bipolar 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 0

0111 1111 1111 +V

REF

(1 / 2048)

0000 0000 0001 -V

REF

(2047 / 2048)

0000 0000 0000 -V

REF

(2048 / 2048) = -V

REF

Figure 8. Bipolar Output Circuit

MAX5290

DAC_

REF

OUT_

10kΩ 10kΩ

V+

V-

OUT_

MAX5291

DAC_

REF

OUT_

FB_

R2 = 12kΩ

0.1%

25ppm

R1 = 10kΩ

0.1%

25ppm

Figure 9. Configurable Output Gain

1 2 ... 23 24 25 26 27 28 29 30 31 32 33

Kommentare zu diesen Handbüchern

Keine Kommentare

Rainbow-electronics MAX5295 Bedienungsanleitung Seite 28

Kommentare zu diesen Handbüchern

Verwandte Produkte und Handbücher für Sensoren Rainbow-electronics MAX5295