AD7808 Просмотр технического описания (PDF) - Analog Devices

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Компоненты Описание

производитель

AD7808

+3.3 V to +5 V Quad/Octal 10-Bit DACs

Analog Devices 

AD7804/AD7805/AD7808/AD7809

AD7805

Pin No.

1

2, 3

4

5–10,

12, 13

19, 20

11

14

15

16

17

18

21, 22

23

24

25

26, 27

28

AD7805/AD7809 PIN FUNCTION DESCRIPTIONS

AD7809

Pin No.

Mnemonic

Description

1, 11, 13,

20, 33

2, 5, 39, 40

41, 42

43

3, 4, 6, 7, 9,

10, 15, 23

24, 26

8, 12

14

16

17

18

21

19

22, 25

27, 29, 30

31

32

34

35, 36

28, 37, 38

44

NC

AGND

VOUTB, VOUTA

REFOUT

DB9–DB2

DB1, DB0

VOUTF, VOUTE

LDAC

DGND

DVDD

WR

CS

CLR

VOUTH, VOUTG

A2, A1, A0

MODE

REFIN

COMP

VOUTD, VOUTC

AVDD

PD

No Connect. These pins should be left open circuit.

Ground reference point for analog circuitry.

Analog output voltages from the DACs.

Reference Output. This is a bandgap reference and is typically 1.23 V.

Data Inputs. DB9 to DB2 are the 8 MSBs of the data word.

DB1 and DB0 function as the 2 LSBs of the 10-bit word in 10-bit parallel mode but

have other functions when BYTE loading structure is used.

Analog output voltages from the DACs.

LDAC Input. When this digital input is taken low, all DAC registers are simultaneously

updated with the contents of the DAC data registers. If LDAC is permanently tied low, or is

low during the rising edge of WR similar to data inputs, an automatic update will take place.

Ground reference point for digital circuitry.

Digital Power Supply.

Write Input WR is an active low logic input which is used in conjunction with CS and

the address pins to write data to the relevant registers.

Chip Select. Active low logic input.

Asynchronous CLR Input. When this input is taken low, all Main DAC outputs are

cleared either to VBIAS or to VBIAS/16 volts. All Sub DACs are also cleared and thus the

transfer function of the MAIN DAC will remain centered around the VBIAS point.

Analog output voltages from the DACs.

DAC Address Inputs. These digital inputs are used in conjunction with CS and WR to

determine which DAC channel control register or DAC data register is loaded from the

input register. These address bits are don’t cares when writing to the system control register.

Logic Input. Logic high enables writing to the DAC data registers, a logic low enables

writing to the control registers.

This is an external reference input for the DAC. When this reference is selected for the DAC

in the control register, the analog output from the selected DAC swings around this point.

Compensation Pin. This pin provides an output from the internal VDD/2 divider and is

provided for ac bypass purposes only. This pin should be decoupled with 1 nF capacitors

to both AVDD and AGND. This pin can be overdriven with an external reference, thus

giving the facility for two external references on the part.

Analog output voltages from the DACs.

Analog Power Supply.

Active low input used to put the part into low power mode reducing current consump-

tion to 1 µA.

AD7805 PIN CONFIGURATION

AD7809 PIN CONFIGURATION

AGND 1

VOUTB 2

VOUTA 3

REFOUT 4

28 AVDD

27 VOUTC

26 VOUTD

25 COMP

DB9 5

24 REFIN

DB8 6

23 MODE

AD7805

DB7 7 TOP VIEW 22 A0

DB6 8 (Not to Scale) 21 A1

DB5 9

20 DB0

DB4 10

19 DB1

LDAC 11

18 CLR

DB3 12

17 CS

DB2 13

16 WR

DGND 14

15 DVDD

44 43 42 41 40 39 38 37 36 35 34

NC 1

AGND 2

DB9 3

DB8 4

AGND 5

DB7 6

DB6 7

VOUTF 8

DB5 9

DB4 10

NC 11

PIN 1

IDENTIFIER

AD7809

TOP VIEW

(Not to Scale)

33 NC

32 REFIN

31 MODE

30 A0

29 A1

28 AVDD

27 A2

26 DB0

25 VOUTG

24 DB1

23 DB2

12 13 14 15 16 17 18 19 20 21 22

NC = NO CONNECT

–8–

REV. A

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