AD5330_08 datasheet(20/28 Pages) AD

20 / 28 page

AD5330/AD5331/AD5340/AD5341

Rev. A | Page 20 of 28

SUGGESTED DATABUS FORMATS

In most applications, GAIN and BUF are hard-wired. However,

if more flexibility is required, they can be included in a databus.

This enables the user to software program GAIN, giving the

option of doubling the resolution in the lower half of the DAC

range. In a bused system, GAIN and BUF can be treated as data

inputs because they are written to the device during a write

operation and take effect when LDAC is taken low. This means

that the reference buffers and the output amplifier gain of

multiple DAC devices can be controlled using common GAIN

and BUF lines.

In the case of the AD5330, this means that the databus must be

wider than eight bits. The AD5331 and AD5340 databuses must

be at least 10 bits and 12 bits wide, respectively, and are best

suited to a 16-bit databus system.

Examples of data formats for putting GAIN and BUF on a

16-bit databus are shown in Figure 40. Note that any unused bits

above the actual DAC data can be used for BUF and GAIN. DAC

devices can be controlled using common GAIN and BUF lines.

AD5331

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

GAIN

BUF

AD5330

AD5340

X = UNUSED BIT

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

GAIN

BUF

DB9 DB8

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

GAIN

BUF

DB9 DB8

DB10

DB11

Figure 40. GAIN and BUF Data on a 16-Bit Bus

The AD5341 is a 12-bit device that uses byte load, so only four

bits of the high byte are actually used as data. Two of the unused

bits can be used for GAIN and BUF data by connecting them to

the GAIN and BUF inputs; for example, Bit 6 and Bit 7, as

shown in Figure 41 and Figure 42.

DATA

INPUTS

BUF

GAIN

LDAC

CLR

HBEN

AD5341

DB7

DB6

8-BIT

DATA BUS

Figure 41. AD5341 Data Format for Byte Load with GAIN and BUF Data

on 8-Bit Bus

In this case, the low byte is written to first in a write operation

with HBEN = 0. Bit 6 and Bit 7 of DAC data are written into

GAIN and BUF registers but have no effect. The high byte is

then written to. Only the lower four bits of data are written into

the DAC high byte register, so Bit 6 and Bit 7 can be GAIN and

BUF data.

LDAC is used to update the DAC, GAIN, and BUF values.

DB8

DB9

HIGH BYTE

LOW BYTE

X = UNUSED BIT

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

DB10

DB11

BUF

GAIN

Figure 42. AD5341 with GAIN and BUF Data on 8-Bit Bus

AD5330 датащи(PDF) 20 Page - Analog Devices

AD5330 датащи(HTML) 20 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 24 25 26 27 28

датащи скачать

ссылки URL