Datasheet

DAC7734
22
SBAS138A
www.ti.com
(1)
VVL
VHVLN
OUT REF
REF REF
=+
()
–•
,65 536
FIGURE 11. Daisy-Chaining DAC7734.
SERIAL-DATA OUTPUT
The Serial-Data Output (SDO) is the internal shift register
output. For DAC7734, the SDO is a driven output and does
not require an external pull-up. Any number of DAC7734s
can be daisy-chained by connecting the SDO pin of one
device to the SDI pin of the following device in the chain,
as shown in Figure 11.
DIGITAL TIMING
Figure 12 and Table III provide detailed timing for the
digital interface of the DAC7734.
DIGITAL INPUT CODING
The DAC7734 input data is in Straight Binary format. The
output voltage is given by Equation 1.
(2)
I
VHVL
R
VLR
OUT
REF REF
SENSE
REF SENSE
=


















+
()
–
•
,
/
N
65 536
DIGITALLY-PROGRAMMABLE
CURRENT SOURCE
The DAC7734 offers a unique set of features that allows a
wide range of flexibility in designing applications circuits
such as programmable current sources. The DAC7734 offers
both a differential reference input, as well as an open-loop
configuration around the output amplifier. The open-loop
configuration around the output amplifier allows a transistor
to be placed within the loop to implement a digitally-
programmable, unidirectional current source. The availabil-
ity of a differential reference allows programmability for
both the full-scale and zero-scale currents. The output cur-
rent is calculated as:
where N is the digital input code. This equation does not
include the effects of offset (zero-scale) or gain (full-scale)
errors.
DAC7734
CLK
SDI
CS
SCK
DIN
CS
LDAC
SDO
DAC7734
CLK
SDI
CS
SDO
LOAD
DAC7734
LOAD LOAD LOAD
CLK
SDI
CS
LDAC LDAC LDAC
SDO
To
Other
Serial
Devices