AD7538 データシートの表示（PDF） - Analog Devices

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AD7538

LC2MOS Microprocessor-Compatible 14-Bit DAC

Analog Devices 

AD7538

DIGITAL FEEDTHROUGH

The digital inputs to the AD7538 are directly connected to the

microprocessor bus in the preceding interface configurations.

These inputs are constantly changing even when the device is

not selected. The high frequency logic activity on the bus can

feed through the DAC package capacitance to show up as noise

on the analog output. To minimize this digital feedthrough

isolate the DAC from the noise source. Figure 13 shows an

interface circuit, which uses this technique. All data inputs are

latched from the bus by the CS signal. One may also use other

means, such as peripheral interface devices, to reduce the digital

feedthrough.

A0 TO A15

MICRO-

PROCESSOR

SYSTEM

WR

D0 TO D15

ADDRESS

DECODE

EN

16-BIT

LATCH

AD75381

CS

LDAC

WR

DB0 TO DB13

1LINEAR CIRCUITRY OMITTED FOR CLARITY.

Figure 13. AD7538 Interface Circuit Using Latches to Minimize Digital

Feedthrough

Rev. B | Page 14 of 16

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