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NOTES:
(1)10pF tantalum tor
optimum settling
performance.
(2) Unipolar offset adjust is
not necessary In most
applications.
(3) For the ceramic pack-
age, the lid is corinec-
ted to -Vcc •
FIGURE 5. Power Supply, Gain and Offset Connections.
Brown DAC667 increases the settling time about one micro-
second. The DAC667 settling time is specified at 7jis maxi-
mum. The AD667 is specified at 4(is maximum.
INSTALLATION
POWER SUPPLY CONNECTIONS
Note that the metal lid of the ceramic-packaged DAC667 is
connected to -V^. Take care to avoid accidental short
circuits in tightly spaced iastallations.
Power supply decoupling capacitors should be added as
shown in Figure 5. Best settling performance occurs using a
l^iF to 10|iF tantalum capacitor at -Vgp. Applications with
less critical settling time may be able to use
0.01
pF at -V^
as well as at +V
CC
. The capacitors should be located close to
the DAC667 package.
DAC667 features separate digital and analog power supply
returns to permit optimum connections for low noise and
high speed performance. It is recommended that both power
ground (pin 16) and analog ground (AGND, pin 5) be
connected directly to a ground plane under the package. If a
ground plane is not used, connect the AGND and power
ground pins together close to the package. Since the refer-
ence point for V
OUT
and V^q^ is the AGND pin, it is also
important to connect the load directly to the AGND pin.
The change in current in the AGND pin due to an input data
word change from OOOhex to FFFjjgx is only I mA.
OUTPUT VOLTAGE SWING
AND RANGE CONNECTIONS
The DAC667 output amplifier can provide ±10V output
swing while operating on ± 11.4V supplies. The Analog
Devices AD667 requires a minimum of 112.5V to achieve
an output swing of ±10V.
Internal scaling resistors provided in the DAC667 may be
connected to produce bipolar output voltage ranges of ± 10V,
±5 V or ±2.5 V or unipolar output voltage ranges of 0 to +5V
or 0 to +10V. Refer to Figures 6, 7 and 8. Connections for
various output ranges are shown in Table III.
The internal feedback resistors (5kfl) and the bipolar offset
resistor (9.95kO) are trimmed to an absolute tolerance of
about ±10%.
FIGURE 6. Output Amplifier Voltage Range Scaling Circuit.
3.52
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