LTC1650 Linear Technology, LTC1650 Datasheet - Page 9

• Manufacturer Part Number: LTC1650
• Description: Low Glitch 16-Bit Voltage Output DAC
• Manufacturer: Linear Technology

OPERATIO
Serial Interface
The data on the D
on the rising edge of the clock. Data is loaded as one
16-bit word, MSB first. The DAC register loads the data
from the shift register when CS/LD is pulled high. The
clock is disabled internally when CS/LD is high. Note: CLK
must be low before CS/LD is pulled low to avoid an extra
internal clock pulse.
The buffered output of the 16-bit shift register is available
on the D
Multiple LTC1650s may be daisy-chained together by
connecting the D
while the clock and CS/LD signals remain common to all
chips in the daisy chain. The serial data is clocked to all of
the chips, then the CS/LD signal is pulled high to update all
of them simultaneously.
When CLR is pulled low or when the part powers up, the
output connects through an internal pass gate to V
will go to whatever voltage is on V
supplies (DV
RSTOUT pin goes low and stays low as long as the supply
is below 2.5V. The power-on reset is also activated when
one of the supplies drops below 2.5V and the output is
then connected to V
when any of three conditions occur: CLR goes low, the part
OUT
pin which swings from DGND to DV
DD
, AV
OUT
U
IN
input is loaded into the shift register
DD
RST
pin to the D
, |AV
. The output connects to V
SS
|) goes below 2.5V, the
RST
IN
pin of the next chip
. When any of three
DD
RST
.
and
RST
powers up or one of the supplies drops below 2.5V. This
condition exists as long as CS/LD is low. As soon as CS/
LD goes high, the DAC register is loaded with the data in
the shift register and the output will settle to its new value.
Voltage Output
The LTC1650 rail-to-rail buffered output can source or
sink 5mA over the entire operating temperature range. The
output can swing to within a few millivolts of either supply
rail when unloaded and has an equivalent output resis-
tance of 50 when driving a load to the rails. The buffer
amplifier can drive 1000pF without going into oscillation.
The LTC1650 has a deglitched voltage output. The midscale
glitch is less than 2nV-s. The digital feedthrough is about
0.05nV-s.
Output Ranges
The LTC1650 is capable of unipolar or bipolar output
swing. When the UNI/BIP pin is connected to V
is configured for unipolar operation and the output will
swing from REFLO to REFHI. When UNI/BIP is connected
to REFHI the part is configured in bipolar mode and the
output will swing from (2 • REFLO – REFHI) to REFHI and
will be at REFLO at midscale. With REFLO = 0V the output
swing is REFHI in bipolar mode and 0V to REFHI in
unipolar mode.
LTC1650
OUT
the part
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