AD5330 Analog Devices, AD5330 Datasheet - Page 20

• Manufacturer Part Number: AD5330
• Manufacturer: Analog Devices

Specifications of AD5330

• Resolution (bits): 8bit
• Dac Update Rate: 167kSPS
• Dac Settling Time: 6µs
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Voltage Out
• Dac Input Format: Par

AD5330/AD5331/AD5340/AD5341
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.
X = UNUSED BIT
BUF
BUF
BUF
GAIN
GAIN
GAIN
X
X
X
Figure 40. GAIN and BUF Data on a 16-Bit Bus
X
X
X
DB
X
X
11
DB
X
X
10
DB
DB
X
9
9
DB
DB
AD5330
AD5331
AD5340
X
8
8
DB
DB
DB
7
7
7
DB
DB
DB
6
6
6
DB
DB
DB
5
5
5
DB
DB
DB
4
4
4
DB
DB
DB
3
3
3
DB
DB
DB
2
2
2
DB
DB
DB
1
1
1
DB
DB
DB
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0
0
0
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.
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.
X = UNUSED BIT
Figure 41. AD5341 Data Format for Byte Load with GAIN and BUF Data
DB
BUF
7
Figure 42. AD5341 with GAIN and BUF Data on 8-Bit Bus
GAIN
DB
DATA BUS
6
8-BIT
DB
5
X
DB
6
DB
DB
HIGH BYTE
on 8-Bit Bus
LOW BYTE
X
7
4
BUF
GAIN
LDAC
CLR
CS
WR
HBEN
DB
DB
DATA
INPUTS
11
3
AD5341
DB
DB
10
2
DB
DB
9
1
DB
DB
0
8