AD7865 查看數據表（PDF） - Analog Devices

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AD7865

Four-Channel, Simultaneous Sampling, Fast, 14-Bit ADC

Analog Devices 

Pin

Mnemonic

24

VREF

25

26

27–34

AVDD

AGND

DB13–DB6

35

DVDD

36

VDRIVE

37

DGND

38, 39

40–43

DB5, DB4

DB3–DB0

44

EOC

AD7865

Description

Reference Input/Output. This pin provides access to the internal reference (2.5 V ± 20 mV)

and also allows the internal reference to be overdriven by an external reference source (2.5 V

± 5%). A 0.1 µF decoupling capacitor should be connected between this pin and AGND.

Analog Positive Supply Voltage, 5.0 V ± 5%. A 0.1 µF decoupling capacitor should be con-

nected between this pin and AGND.

Analog Ground. General Analog Ground. This AGND pin should be connected to the system’s

AGND plane.

Data Bit 13 is the MSB, followed by Data Bit 12 to Data Bit 6. Three-state TTL outputs.

Output coding is twos complement for AD7865-1 and AD7865-3, and straight binary for

AD7865-2.

Positive Supply Voltage for Digital section, 5.0 V ± 5%. A 0.1 µF decoupling capacitor should

be connected between this pin and AGND. Both DVDD and AVDD should be externally tied

together.

This pin provides the positive supply voltage for the output drivers (DB0 to DB13), BUSY,

EOC and FRSTDATA. It is normally tied to DVDD. VDRIVE should be decoupled with a

0.1 µF capacitor. It allows improved performance when reading during the conversion

sequence. Also, the output data drivers may be powered by a 3 V ± 10% supply to facilitate

interfacing to 3 V processors and DSPs.

Digital Ground. Ground reference for Digital circuitry. This DGND pin should be connected

to the system’s DGND plane. The system’s DGND and AGND planes should be connected

together at one point only, preferably at an AGND pin.

Data Bit 5 to Data Bit 4. Three-state TTL outputs.

Data Bit 3 to Data Bit 0. Bidirectional data pins. When a read operation takes place, these

pins are three-state TTL outputs. The channel select register is programmed with the data on

the DB0–DB3 pins with standard CS and WR signals. DB0 represents Channel 1 and DB3

represents Channel 4.

End-of-Conversion. Active low logic output indicating conversion status. The end of each

conversion in a conversion sequence is indicated by a low going pulse on this line.

REV. B

–7–

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