DAC7741Y Burr-Brown Corporation, DAC7741Y Datasheet - Page 14

• Manufacturer Part Number: DAC7741Y
• Description: 16-Bit/ Single Channel DIGITAL-TO-ANALOG CONVERTER With Internal Reference and Parallel Interface
• Manufacturer: Burr-Brown Corporation

ANALOG OUTPUTS
The output amplifier can swing to within 1.4V of the supply
rails, specified over the –40 C to +85 C temperature range.
This allows for a 10V DAC voltage output operation from
When the DAC7741 is configured for a unipolar, 0V to 10V
output, a negative voltage supply is required. This is due to
internal biasing of the output stage. Please refer to the
“Electrical Characteristics” table for more information.
The minimum and maximum voltage output values are de-
pendent upon the output configuration implemented and
reference voltage applied to the DAC7741. Please note that
V
–4.75V to –15.75V for unipolar operation. The voltage on V
sets several bias points within the converter and is required
in all modes of operation. If V
configurations, the bias values may be in error and proper
operation of the device is not ensured.
Supply sequence is important in establishing the correct
startup of the DAC. The digital supply (V
lish correct bias conditions before the analog supplies (V
V
up first, it must come up before either analog supply (V
V
V
REFERENCE INPUTS
The DAC7741 provides a built-in +10V voltage reference and
on-chip buffer to allow external component reference drive. To
use the internal reference, REFEN must be LOW, enabling the
reference circuitry of the DAC7741 (see Table I) and the
REF
the on-chip reference buffer. The buffers output is provided at
TABLE I. REFEN Action.
14
TABLE II. DAC7741 Logic Truth Table.
12V supplies with a typical 5% tolerance.
R/W CS
SS
SS
SS
DD
X
H
X
X
X
L
L
) are brought up. If the digital supply cannot be brought
), with the preferred sequence of: V
OUT
then V
(the negative power supply) must be in the range of
REFEN
1
0
pin must be connected to REF
H
H
L
L
L
X
X
CC
CONTROL STATUS
.
RST RSTSEL
H
H
H
H
H
L
L
H
X
X
X
X
X
L
Internal Reference disabled;
REF
Internal Reference enabled;
OUT
SS
REF
LDAC
= HIGH Impedance
H, L,
H, L,
H, L,
is not in one of these two
ACTION
OUT
X
X
= +10V
SS
IN
. This is the input to
DD
(device substrate),
Reset to Min-Scale Reset to Min-Scale Reset to Input and DAC Register (0000
Reset to Mid-Scale Reset to Mid-Scale Reset to Input and DAC Register (8000
) needs to estab-
Input Register
Transparent
Read
Write
Hold
Hold
CC
CC
www.ti.com
SS
or
,
DAC Register
the V
DAC7741 output amplifier into one of three voltage output
modes as discussed earlier. V
other system components requiring an external reference.
The internal reference of the DAC7741 can be disabled when
use of an external reference is desired. When using an
external reference, the reference input, REF
voltage between 4.75V (or V
and V
DIGITAL INTERFACE
Table III shows the data format for the DAC7741 and
Table II illustrates the basic control logic of the device. The
interface consists of a chip select input (CS), read/write
control input (R/W), data inputs (DB0-DB15) and a load DAC
input (LDAC). An asynchronous reset input (RST) which is
active low, is provided to simplify start-up conditions, periodic
resets, or emergency resets to a known state, depending on
the status of the reset select (RSTSEL) signal. The DAC
code is provided via a 16-bit parallel interface, as shown in
Table II. The input word makes up the DAC code to be
loaded into the data input register of the device. The data is
latched into the input register on rising CS and is loaded into
the DAC register upon reception of a rising edge on the
LDAC input. This action updates the analog output, V
the desired value. LDAC inputs of multiple DAC7741 devices
can be connected when a synchronized update of numerous
DAC outputs is desired. Please refer to the timing section for
more detailed data I/O information.
TABLE III. DAC7741 Data Format.
DIGITAL INPUT
Write
Write
Hold
Hold
Hold
0xFFFF
0x0000
0x0001
0x8000
0x8001
REF
CC
:
:
– 1.4V.
pin. In this configuration, V
COMMAND
Write Data to Input Register
Update DAC register with data from input
register.
Write DAC register directly from data bus
Read data in input register.
No Change
Min-Scale
Mid-Scale
Full-Scale (V
Unipolar Straight Binary
Unipolar Configuration
1/2 Full-Scale + 1LSB
1/2 Full-Scale
Zero + 1LSB
Zero (0V)
:
:
REF
SS
ANALOG OUTPUT
– 1LSB)
REF
+ 14V, whichever is greater)
can also be used to drive
Mode
REF
–Full-Scale (–V
+Full-Scale (+V
is used to setup the
Bipolar Configuration
Bipolar Offset Binary
Bipolar Zero + 1LSB
–Full-Scale + 1LSB
or +V
Bipolar Zero
IN
REF
DAC7741
, can be any
/2 – 1LSB)
:
:
REF
SBAS248A
REF
or –V
– 1LSB
OUT
H
H
REF
)
)
, to
/2)