DAC8560 Datasheet, PDF (23/29 Pages) Burr-Brown (TI) – 16-Bit, Ultra-Low Glitch, Voltage Output DIGITAL-TO-ANALOG CONVERTER with 2.5V, 2ppm/°C Internal Reference

DAC8560
www.ti.com
Long-Term Stability
Long-term stability/aging refers to the change of the
output voltage of a reference over a period of months
or years. This effect lessens as time progresses, as
shown in Figure 6, the typical long-term stability
curve. The typical drift value for the DAC8560
internal reference is 50ppm from 0 hours to 1900
hours. This parameter is characterized by
powering-up and measuring 20 units at regular
intervals for a period of 1900 hours.
Thermal Hysteresis
Thermal hysteresis for a reference is defined as the
change in output voltage after operating the device
at +25°C, cycling the device through the specified
temperature range, and returning to +25°C. It is
expressed in Equation 3:
ǒ Ǔ V_HYST +
Ť Ť _{V * V REF_PRE}
REF_POST
V_{REF_NOM}
10⁶ (ppm)
Where:
V_HYST = thermal hysteresis.
V_{REF_PRE} = output voltage measured at +25°C
pre-temperature cycling.
V_{REF_POST} = output voltage measured after the
device has been cycled through the temperature
range of –40°C to +120°C, and returned to
+25°C.
DAC NOISE PERFORMANCE
Typical noise performance for the DAC8560 with the
internal reference enabled is shown in Figure 39 to
Figure 41. Output noise spectral density at pin V_OUT
versus frequency is depicted in Figure 39 for
full-scale, midscale, and zero scale input codes. The
typical noise density for midscale code is 170nV/√Hz
at 1kHz and 100nV/√Hz at 1MHz. High-frequency
noise can be improved by filtering the reference
noise as shown in Figure 40, where a 4µF load
capacitor is connected to the V_REF pin and compared
to the no-load condition. Integrated output noise
between 0.1Hz and 10Hz is close to 50µV_PP
(midscale), as shown in Figure 41.
BIPOLAR OPERATION USING THE DAC8560
The DAC8560 has been designed for single-supply
operation, but a bipolar output range is also possible
using the circuit in either Figure 69 or Figure 70. The
circuit shown gives an output voltage range of ±V_REF.
Rail-to-rail operation at the amplifier output is
achievable using an OPA703 as the output amplifier.
SLAS464 – DECEMBER 2006
V
REF
V
DD
R₁
10kW
R₂
10kW
+6V
OPA703
±5V
V_DD
V_FB
V_{REF DAC8560} V_OUT
10mF
0.1mF
-6V
GND
Three-Wire
Serial Interface
Figure 69. Bipolar Output Range Using External
Reference at 5V
V
DD
R₁
10kW
V_DD
V_{REF DAC8560}
V_FB
V_OUT
150nF
GND
R₂
10kW
+6V
OPA703
-6V
±2.5V
Three-Wire
Serial Interface
Figure 70. Bipolar Output Range Using Internal
Reference
The output voltage for any input code can be
calculated as using Equation 4:
ƪ ǒ Ǔ ǒ Ǔ ǒ Ǔƫ V_O + V_REF
D
65536
R₁ ) R₂
R₁
* V_REF
R₂
R₁
where D represents the input code in decimal
(0–65535).
With V_REF = 5V, R₁ = R₂ = 10kΩ.
ǒ Ǔ V_O +
10 D
65536
* 5V
This result has an output voltage range of ±5V with
0000h corresponding to a –5V output and FFFFh
corresponding to a 5V output, as shown in Figure 69.
Similarly, using the internal reference, a ±2.5V output
voltage range can be achieved, as shown in
Figure 70.
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