AD5445 Analog Devices, AD5445 Datasheet - Page 17

• Manufacturer Part Number: AD5445
• Description: High Bandwidth CMOS 12-Bit Parallel Interface Multiplying D/A Converter
• Manufacturer: Analog Devices

Specifications of AD5445

• Resolution (bits): 12bit
• Dac Update Rate: 20.4MSPS
• Dac Settling Time: 80ns
• Max Pos Supply (v): +5.5V
• Single-supply: Yes
• Dac Type: Current Out
• Dac Input Format: Par

Data Sheet
TERMINOLOGY
Relative Accuracy
Relative accuracy or endpoint nonlinearity is a measure of the
maximum deviation from a straight line passing through the
endpoints of the DAC transfer function. It is measured after
adjusting zero scale and full scale and is normally expressed in
LSBs or as a percentage of full-scale reading.
Differential Nonlinearity
Differential nonlinearity is the difference between the measured
change and the ideal 1 LSB change between any two adjacent
codes. A specified differential nonlinearity of –1 LSB maximum
over the operating temperature range ensures monotonicity.
Gain Error
Gain error or full-scale error is a measure of the output error
between an ideal DAC and the actual device output. For these
DACs, ideal maximum output is V
DACs is adjustable to 0 with external resistance.
Output Leakage Current
Output leakage current is current that flows in the DAC ladder
switches when these are turned off. For the I
can be measured by loading all 0s to the DAC and measuring
the I
when the DAC is loaded with all 1s.
Output Capacitance
Capacitance from I
Output Current Settling Time
This is the amount of time it takes for the output to settle to a
specified level for a full-scale input change. For these devices, it
is specified with a 100 Ω resistor to ground.
The settling time specification includes the digital delay from
the CS rising edge to the full-scale output change.
Digital-to-Analog Glitch lmpulse
The amount of charge injected from the digital inputs to the
analog output when the inputs change state. This is normally
specified as the area of the glitch in either pA seconds or nV
seconds, depending upon whether the glitch is measured as a
current or voltage signal.
OUT
1 current. Minimum current flows in the I
OUT
1, or I
OUT
2, to AGND.
REF
– 1 LSB. Gain error of the
OUT
1 terminal, it
OUT
2 line
Rev. C | Page 17 of 28
Digital Feedthrough
When the device is not selected, high frequency logic activity
on the device digital inputs may be capacitively coupled
through the device to show up as noise on the I
subsequently in the following circuitry. This noise is called
digital feedthrough.
Multiplying Feedthrough Error
This is the error due to capacitive feedthrough from the DAC
reference input to the DAC I
loaded to the DAC.
Total Harmonic Distortion (THD)
The DAC is driven by an ac reference. The ratio of the rms sum
of the harmonics of the DAC output to the fundamental value is
the THD. Usually only the lower order harmonics are included,
such as second to fifth.
Digital Intermodulation Distortion
Second-order intermodulation distortion (IMD) measurements
are the relative magnitude of the fa and fb tones generated
digitally by the DAC and the second-order products at 2fa − fb
and 2fb − fa.
Spurious-Free Dynamic Range (SFDR)
SFDR is the usable dynamic range of a DAC before spurious
noise interferes or distorts the fundamental signal. It is measured
by the difference in amplitude between the fundamental and the
largest harmonically or nonharmonically related spur from dc
to full Nyquist bandwidth (half the DAC sampling rate, or f
Narrow-band SFDR is a measure of SFDR over an arbitrary
window size, in this case, 50% of the fundamental. Digital SFDR
is a measure of the usable dynamic range of the DAC when the
signal is a digitally generated sine wave.
THD
=
20
log
(
V
2
2
AD5424/AD5433/AD5445
+
V
OUT
3
V
2
+
1
1 terminal when all 0s are
V
4
2
+
V
5
2
)
OUT
pins and
S
/2).