AD7849AR-REEL Analog Devices Inc, AD7849AR-REEL Datasheet - Page 16

• Manufacturer Part Number: AD7849AR-REEL
• Description: IC DAC 16BIT SRL INP 20-SOIC
• Manufacturer: Analog Devices Inc

Specifications of AD7849AR-REEL

• Rohs Status: RoHS non-compliant
• Settling Time: 7µs
• Number Of Bits: 16
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Analog and Digital, Dual ±
• Power Dissipation (max): 100mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)

AD7849-to-TMS320C2x Interface
Figure 25 shows a serial interface between the AD7849 and the
TMS320C2x DSP processor. In this interface, the CLKX and
FSX signals for the TMS320C2x should be generated using
external clock/timer circuitry. The FSX pin of the TMS320C2x
must be configured as an input. Data from the TMS320C2x is
valid on the falling edge of CLKX.
The clock/timer circuitry generates the LDAC signal for the
AD7849
transmission. Alternatively, the automatic update mode can be
selected by connecting
AD7849-to-68HC11 Interface
Figure 26 shows a serial interface between the AD7849 and the
68HC11 microcontroller. SCK of the 68HC11 drives SCLK of
the AD7849, while the MOSI output drives the serial data line
of the AD7849. The SYNC signal is derived from a port line
(PC0 shown).
For correct operation of this interface, the 68HC11 should be
configured such that its CPOL bit is a 0 and its CPHA bit is a 1.
When data is transmitted to the part, PC0 is taken low. When
the 68HC11 is configured like this, data on MOSI is valid on the
falling edge of SCK. The 68HC11 transmits its serial data in 8-bit
bytes with only eight falling clock edges occurring in the transmit
cycle. To load data to the AD7849, PC0 is left low after the first
eight bits are transferred, and a second byte of data is then
transferred serially to the AD7849. When the second serial
transfer is complete, the PC0 line is taken high.
AD7849
*ADDITIONAL PINS OMITTED FOR CLARITY.
TMS320C2x
to synchronize the update of the output with the serial
Figure 25. AD7849-to-TMS320C2x Interface
CLKX
FSX
DX
LDAC to DGND.
CLOCK/TIMER
SYNC
SCLK
SDIN
AD7849*
LDAC
Rev. C | Page 16 of 20
Figure 26 shows the LDAC input of the
from another bit programmable port line (PC1). As a result, the
DAC can be updated by taking
register has been loaded.
AD7849-to-87C51 Interface
A serial interface between the
microcontroller is shown in Figure 27. TXD of the 87C51 drives
SCLK of the AD7849, while RXD drives the serial data line of
the part. The SYNC signal is derived from the P3.3 port line,
and the LDAC line is driven from the P3.2 port line.
The 87C51 provides the LSB of its SBUF register as the first bit
in the serial data stream. Therefore, ensure that the data in the
SBUF register is arranged correctly so that the most significant
bits are the first to be transmitted to the AD7849, and the last
bit to be sent is the LSB of the word to be loaded to the AD7849.
When data is transmitted to the part, P3.3 is taken low. Data on
RXD is valid on the falling edge of TXD. The 87C51 transmits
its serial data in 8-bit bytes, with only eight falling clock edges
occurring in the transmit cycle. To load data to the AD7849, P3.3 is
left low after the first eight bits are transferred, and a second byte of
data is then transferred serially to the AD7849. When the second
serial transfer is complete, the P3.3 line is taken high.
Figure 27 shows the LDAC input of the
the bit programmable P3.2 port line. As a result, the DAC output
can be updated by taking the
completion of the write cycle. Alternatively, LDAC can be
hardwired low, and the analog output is updated on the 16th
falling edge of TXD after the SYNC signal for the DAC goes low.
*ADDITIONAL PINS OMITTED FOR CLARITY.
*ADDITIONAL PINS OMITTED FOR CLARITY.
68HC11*
87C51*
Figure 26. AD7849-to-68HC11 Interface
MOSI
Figure 27. AD7849-to-87C51 Interface
PC1
PC0
SCK
RXD
P3.3
TXD
P3.2
LDAC line low following the
AD7849
LDAC low after the DAC input
and the 87C51
AD7849
AD7849
LDAC
SYNC
SCLK
SDIN
SCLK
SDIN
LDAC
SYNC
AD7849*
AD7849*
being driven
driven from