PCM55 BURR-BROWN [Burr-Brown Corporation], PCM55 Datasheet - Page 5

• Manufacturer Part Number: PCM55
• Description: 16-Bit Monolithic DIGITAL-TO-ANALOG CONVERTERS
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

FIGURE 3. Full-Scale Range Settling Time vs Accuracy.
POWER SUPPLY SENSITIVITY
Changes in the DC power supplies will affect accuracy.
The PCM54 and PCM55 power supply sensitivity is shown
by Figure 2. Normally, regulated power supplies with 1% or
less ripple are recommended for use with the DAC. See also
Power Supply Connections paragraph in the Installation and
Operating Instructions section.
FIGURE 2. Effects of V
SETTLING TIME
Settling time is the total time (including slew time) required
for the output to settle within an error band around its final
value after a change in input (see Figure 3).
Settling times are specified to 0.006% of FSR; one for a
large output voltage change of 3V and one for a 1LSB
change. The 1LSB change is measured at the major carry
(0111…11 to 10000.00), the point at which the worst-case
settling time occurs.
0.003
0.001
0.003
0.001
10.0
0.30
0.10
0.03
0.01
0.03
0.01
3.0
1.0
1.0
0.3
0.1
0.01
(PCM54JP; V
R
L
= 200
5
0.1
CC
CC
Settling Time ( s)
V
10
s with approximately 2% ripple).
Current
CC
Output
on Total Harmonic Distortion
Mode
Supplies (V)
15
1.0
–60dB
–20dB
Voltage
0dB
Output
Mode
10.0
5
STABILITY WITH TIME AND TEMPERATURE
The parameters of a D/A converter designed for audio
applications should be stable over a relatively wide tempera-
ture range and over long periods of time to avoid undesirable
periodic readjustment. The most important parameters are
bipolar zero, differential linearity error, and total harmonic
distortion. Most of the offset and gain drift with temperature
or time is due to the drift of the internal reference zener
diode. The PCM54 and PCM55 are designed so that these
drifts are in opposite directions so that the bipolar zero
voltage is virtually unaffected by variations in the reference
voltage. Both DLE and THD are dependent upon the match-
ing and tracking of resistor ratios and upon V
the current-source transistors. The PCM54 and PCM55 were
designed so that any absolute shift in these components has
virtually no effect on DLE or THD. The resistors are made
of identical links of ultra-stable nichrome thin-film. The
current density in these resistors is very low to further
enhance their stability.
DYNAMIC RANGE
The dynamic range is a measure of the ratio of the smallest
signals the converter can produce to the full-scale range and
is usually expressed in decibels (dB). The theoretical dy-
namic range of a converter is approximately 6 x n, or about
96dB for a 16-bit converter. The actual, or useful, dynamic
range is limited by noise and linearity errors and is therefore
somewhat less than the theoretical limit. However, this does
point out that a resolution of at least 16 bits is required to
obtain a 90dB minimum dynamic range, regardless of the
accuracy of the converter. Another specification that is
useful for audio applications is total harmonic distortion.
TOTAL HARMONIC DISTORTION
THD is useful in audio applications and is a measure of the
magnitude and distribution of the linearity error, differential
linearity error, and noise as well as quantization error. To be
useful, THD should be specified for both high level and low
level input signals. This error is unadjustable and is the most
meaningful indicator of D/A converter accuracy for audio
applications.
The THD is defined as the ratio of the square root of the sum
of the squares of the values of the harmonics to the value of
the fundamental input frequency and is expressed in percent
or dB. The rms value of the PCM54/55 error referred to the
input can be shown to be:
where n is the number of samples in one cycle of any given
sine wave, E
PCM55 at each sampling point, and E
L
(i) is the linearity error of the PCM54 or
rms
1
n
i
n
1
[
PCM54/55
L
( )
i
Q
(i) is the quantization
Q
( )]
i
2
BE
and h
FE
(1)
of
®