PCM1600 Burr-Brown Corporation, PCM1600 Datasheet - Page 22

• Manufacturer Part Number: PCM1600
• Description: 24-Bit/ 96kHz Sampling/ 6-Channel/ Enhanced Multi-Level/ Delta-Sigma DIGITAL-TO-ANALOG CONVERTER
• Manufacturer: Burr-Brown Corporation

ANALOG OUTPUTS
The PCM1600 includes six independent output channels,
V
capable of driving 3.1Vp-p typical into a 5k AC load with
V
V
voltage, equal to V
The output amplifiers include a RC continuous-time filter,
which helps to reduce the out-of-band noise energy present
at the DAC outputs due to the noise shaping characteristics
of the PCM1600’s delta-sigma D/A converters. The fre-
quency response of this filter is shown in Figure 11. By
itself, this filter is not enough to attenuate the out-of-band
noise to an acceptable level for most applications. An
external low-pass filter is required to provide sufficient out-
of-band noise rejection. Further discussion of DAC post-
filter circuits is provided in the Applications Information
section of this data sheet.
FIGURE 11. Output Filter Frequency Response.
V
Two unbuffered common-mode voltage output pins, V
(pin 16) and V
purposes. These pins are nominally biased to a DC voltage
level equal to V
external circuitry, a voltage follower is required for buffer-
ing purposes. Figure 12 shows an example of using the
V
FIGURE 12. Biasing External Circuits Using the V
OUT
CC
OUT
COM
COM
–100
PCM1600
PCM1601
= +5V. The internal output amplifiers for V
1 through V
6 are DC biased to the common-mode (or bipolar zero)
–20
–40
–60
–80
1 AND V
1 and V
20
0
V
V
COM
COM
1
1
2
®
and V
COM
16
15
COM
10
COM
PCM1600, PCM1601
CC
OUT
2 pins for external biasing applications.
2 (pin 15), are brought out for decoupling
/2. If these pins are to be used to bias
CC
2 OUTPUTS
COM
6. These are unbalanced outputs, each
100
/2.
+
2 Pins.
10 F
Log Frequency (Hz)
1k
4
3
OPA337
10k
100k
1
OUT
V
1M
BIAS
1 through
V
10M
2
CC
COM
COM
1
1
22
ZERO FLAG AND INFINITE ZERO DETECT MUTE
FUNCTIONS
The PCM1600 includes circuitry for detecting an all ‘0’ data
condition for the data input pins, DATA1 through DATA3.
This includes two independent functions: Zero Output Flags
and Zero Detect Mute.
Although the flag and mute functions are independent of one
another, the zero detection mechanism is common to both
functions.
Zero Detect Condition
Zero Detection for each output channel is independent from
the others. If the data for a given channel remains at a ‘0’
level for 1024 sample periods (or LRCK clock periods), a
Zero Detect condition exists for the that channel.
Zero Output Flags
Given that a Zero Detect condition exists for one or more
channels, the Zero flag pins for those channels will be set to
a logic ‘1’state. There are Zero Flag pins for each channel,
ZERO1 through ZERO6 (pins 1 through 6). In addition, all
six Zero Flags are logically ANDed together and the result
provided at the ZEROA pin (pin 48), which is set to a logic
‘1’ state when all channels indicate a zero detect condition.
The Zero Flag pins can be used to operate external mute
circuits, or used as status indicators for a microcontroller,
audio signal processor, or other digitally controlled func-
tions.
Infinite Zero Detect Mute
Infinite Zero Detect Mute is an internal logic function. The
Zero Detect Mute can be enabled or disabled using the INZD
bit of Control Register 8. The reset default is Zero Detect
Mute disabled, INZD = 0. Given that a Zero Detect Condi-
tion exists for one or more channels, the zero mute circuitry
will immediately force the corresponding DAC output(s) to
the bipolar zero level, or V
switching the input of the DAC output amplifier from the
delta-sigma modulator output to the DC common-mode
reference voltage.
APPLICATIONS INFORMATION
CONNECTION DIAGRAMS
A basic connection diagram is shown in Figure 13, with the
necessary power supply bypassing and decoupling compo-
nents. Burr-Brown recommends using the component values
shown in Figure 13 for all designs.
A typical application diagram is shown in Figure 14. Burr-
Brown’s REG1117-3.3 is used to generate +3.3V for V
from the +5V analog power supply. Burr-Brown’s PLL1700E
is used to generate the system clock input at SCLKI, as well
as generating the clock for the audio signal processor.
The use of series resistors (22 to 100 ) are recommended
for SCLKI, LRCK, BCK, DATA1, DATA2, and DATA3.
The series resistor combines with the stray PCB and device
input capacitance to form a low-pass filter which removes
high frequency noise from the digital signal, thus reducing
high frequency emission.
CC
/2. This is accomplished by
DD