ANALOG OUTPUTS
THEORY OF OPERATION
When VSS = –5V (dual supply operation), the output
amplifier can swing to within 2.25V of the supply rails,
over the –40°C to +85°C temperature range. With VSS = 0V
(single-supply operation), the output can swing to ground.
Note that the settling time of the output op amp will be
longer with voltages very near ground. Also, care must be
taken when measuring the zero-scale error when VSS = 0V.
If the output amplifier has a negative offset, the output
voltage may not change for the first few digital input codes
(000H, 001H, 002H, etc.) since the output voltage cannot
swing below ground.
The DAC7614 is a quad, serial input, 12-bit, voltage output
DAC. The architecture is a classic R-2R ladder configuration
followed by an operational amplifier that serves as a buffer.
Each DAC has its own R-2R ladder network and output op
amp, but all share the reference voltage inputs. The minimum
voltage output (“zero-scale”) and maximum voltage output
(“full-scale”) are set by external voltage references (VREFL
and VREFH, respectively). The digital input is a 16-bit serial
word that contains the 12-bit DAC code and a 2-bit address
code that selects one of the four DACs (the two remaining
bits are unused). The converter can be powered from a single
+5V supply or a dual ±5V supply. Each device offers a reset
function which immediately sets all DAC output voltages and
internal registers to either zero-scale (code 000H) or mid-scale
(code 800H). The reset code is selected by the state of the
RESETSEL pin (LOW = 000H, HIGH = 800H). See Figures
1 and 2 for the basic operation of the DAC7614.
The behavior of the output amplifier can be critical in some
applications. Under short-circuit conditions (DAC output
shorted to ground), the output amplifier can sink a great deal
more current than it can source. See the Specifications table
for more details concerning short-circuit current.
+5V
DAC7614(1)
+
1µF to 10µF
0.1µF
0.1µF
1
2
3
4
5
6
7
8
VDD
RESETSEL 16
Reset DACs(2)
VOUTD
VOUTC
VREFL
VREFH
VOUTB
VOUTA
VSS
RESET 15
LOADDACS 14
NIC 13
0V to +2.5V
0V to +2.5V
Update Selected Register
+2.500V
Chip Select
Clock
CS 12
CLK 11
0V to +2.5V
0V to +2.5V
Serial Data In
SDI 10
GND
9
NOTES: (1) P and U package pin configurations shown. (2) As configured, RESET LOW sets all internal registers
to code 000H (0V). If RESETSEL is HIGH, RESET LOW sets all internal registers to code 800H (1.25V).
FIGURE 1. Basic Single-Supply Operation of the DAC7614.
DAC7614(1)
+5V
+
1µF to 10µF
0.1µF
+5V
1
2
3
4
5
6
7
8
VDD
RESETSEL 16
Reset DACs(2)
VOUTD
VOUTC
VREFL
VREFH
VOUTB
VOUTA
VSS
RESET 15
LOADDACS 14
NIC 13
–2.5V to +2.5V
–2.5V to +2.5V
Update Selected Register
–2.500V
0.1µF
0.1µF
Chip Select
Clock
CS 12
+2.500V
CLK 11
Serial Data In
SDI 10
–2.5V to +2.5V
–2.5V to +2.5V
GND
9
–5V
1µF to 10µF
0.1µF
+
NOTES: (1) P and U package pin configurations shown. (2) As configured, RESET LOW sets all internal register
to code 800H (0V). If RESETSEL is LOW, RESET LOW sets all internal registers to code 000H (–2.5V).
FIGURE 2. Basic Dual-Supply Operation of the DAC7614.
®
9
DAC7614
BB [ BURR-BROWN CORPORATION ]
