DAC8420FSZ datasheet(17/23 Pages) AD

17 / 23 page

Data Sheet

DAC8420

Rev. C | Page 17 of 23

Like all amplifiers, the DAC8420 output buffers do generate

voltage noise, 52 nV/√Hz typically. This is easily reduced by

adding a simple RC low-pass filter on each output.

REFERENCE CONFIGURATION

The two reference inputs of the DAC8420 allow a great deal

of flexibility in circuit design. The user must take care, however,

to observe the minimum voltage input levels on VREFHI and

VREFLO to maintain the accuracy shown in the data sheet.

These input voltages can be set anywhere across a wide range

within the supplies, but must be a minimum of 2.5 V apart in

any case (see Figure 30). A wide output voltage range can be

obtained with ±5 V references, which can be provided by the

AD588 as shown in Figure 33. Many applications utilize the

DACs to synthesize symmetric bipolar waveforms, which

require an accurate, low drift bipolar reference.

The AD588 provides both voltages and needs no external

components. Additionally, the device is trimmed in production

for 12-bit accuracy over the full temperature range without user

calibration. Performing a clear with the reset select CLSEL high

allows the user to easily reset the DAC outputs to midscale, or

0 V in these applications.

When driving the reference inputs VREFHI and VREFLO, it is

important to note that VREFHI both sinks and sources current,

and that the input currents of both are code dependent. Many

voltage reference products have a limited current sinking capability

and must be buffered with an amplifier to drive VREFHI in order

to maintain overall system accuracy. The input VREFLO, however,

has no such requirement.

DAC8420

0.1µF

+15V

SUPPLY

–15V

SUPPLY

SYSTEM

GROUND

+5V

–5V

+VS

–VS

AD588

1µF

DAC A

DAC B

DAC C

DAC D

DIGITAL

CONTROLS

GND

DIGITAL INPUTS

VREFHI

+5V

VREFLO

–5V

+15V SUPPLY

0.1µF

–15V SUPPLY

0.1µF

VOUTA

VOUTB

VOUTC

VOUTD

Figure 33. ±10 V Bipolar Reference Configuration Using the AD588

DAC8420FSZ датащи(PDF) 17 Page - Analog Devices

DAC8420FSZ датащи(HTML) 17 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

датащи скачать

ссылки URL