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PDF PCM63P-J Data sheet ( Hoja de datos )
| Número de pieza | PCM63P-J | |
| Descripción | Colinear 20-Bit Monolithic Audio DIGITAL-TO-ANALOG CONVERTER | |
| Fabricantes | Burr-Brown Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de PCM63P-J (archivo pdf) en la parte inferior de esta página. Total 10 Páginas | ||
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®
PCM63P
PCM63P
DEMO BOARD
AVAILABLE
See Appendix A
Colinear ™ 20-Bit Monolithic Audio
DIGITAL-TO-ANALOG CONVERTER
FEATURES
DESCRIPTION
q COLINEAR 20-BIT AUDIO DAC
q NEAR-IDEAL LOW LEVEL OPERATION
q GLITCH-FREE OUTPUT
q ULTRA LOW –96dB max THD+N
(Without External Adjustment)
q 116dB SNR min (A-Weight Method)
q INDUSTRY STD SERIAL INPUT FORMAT
q FAST (200ns) CURRENT OUTPUT
(±2mA; ±2% max)
q CAPABLE OF 16x OVERSAMPLING
q COMPLETE WITH REFERENCE
The PCM63P is a precision 20-bit digital-to-analog
converter with ultra-low distortion (–96dB max with a
full scale output; PCM63P-K). Incorporated into the
PCM63P is a unique Colinear dual-DAC per channel
architecture that eliminates unwanted glitches and
other nonlinearities around bipolar zero. The PCM63P
also features a very low noise (116dB max SNR;
A-weighted method) and fast settling current output
(200ns typ, 2mA step) which is capable of 16-times
oversampling rates.
Applications include very low distortion frequency
synthesis and high-end consumer and professional
digital audio applications.
+5V
Analog
2
+5V
Digital
13
–5V
Analog
28
–5V
Digital
11
Upper Lower
B2 Adj B2 Adj
23 24
Clock 18
Latch Enable 20
Data 21
Input Shift
Register
and
Control
Logic
Upper DAC
Positive
Data Latches
Lower DAC
Negative
Data Latches
19-Bit
Upper
DAC
PCM63P
Colinear 20-Bit DAC
9 RFEEDBACK
19-Bit
Lower
DAC
10 RFEEDBACK
6 IOUT
Buried
Zener
Reference
Servo
Amp
Ref
Amp
5 Bipolar Offset Current
4 Offset Decouple
31
25 7 12
Reference
Decouple
Servo
Decouple
Potentiometer Analog
Voltage
Common
Digital
Common
Colinear ™, Burr-Brown Corp.
International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111
Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1990 Burr-Brown Corporation
PDS-11083F
PCM63PPrinted in U.S.A. January, 1998
®
1 page  
THEORY OF OPERATION
DUAL-DAC COLINEAR ARCHITECTURE
Digital audio systems have traditionally used laser-trimmed,
current-source DACs in order to achieve sufficient accuracy.
However even the best of these suffer from potential low-
level nonlinearity due to errors at the major carry bipolar
zero transition. More recently, DACs employing a different
architecture which utilizes noise shaping techniques and
very high oversampling frequencies, have been introduced
(“Bitstream”, “MASH”, or 1-bit DACs). These DACs over-
come the low level linearity problem, but only at the expense
of signal-to-noise performance, and often to the detriment of
channel separation and intermodulation distortion if the
succeeding circuitry is not carefully designed.
The PCM63 is a new solution to the problem. It combines all
the advantages of a conventional DAC (excellent full scale
performance, high signal-to-noise ratio and ease of use) with
superior low-level performance. Two DACs are combined
in a complementary arrangement to produce an extremely
linear output. The two DACs share a common reference and
a common R-2R ladder to ensure perfect tracking under all
conditions. By interleaving the individual bits of each DAC
and employing precise laser trimming of resistors, the highly
accurate match required between DACs is achieved.
This new, complementary linear or dual-DAC Colinear
approach, which steps away from zero with small steps in
both directions, avoids any glitching or “large” linearity
errors and provides an absolute current output. The low level
performance of the PCM63P is such that real 20-bit resolu-
tion can be realized, especially around the critical bipolar
zero point.
Table I shows the conversion made by the internal logic of
the PCM63P from binary two’s complement (BTC). Also,
the resulting internal codes to the upper and lower DACs
(see front page block diagram) are listed. Notice that only
the LSB portions of either internal DAC are changing
around bipolar zero. This accounts for the superlative per-
formance of the PCM63P in this area of operation.
DISCUSSION OF SPECIFICATIONS
DYNAMIC SPECIFICATIONS
Total Harmonic Distortion + Noise
The key specification for the PCM63P is total harmonic
distortion plus noise (THD+N). Digital data words are read
into the PCM63P at eight times the standard compact disk
audio sampling frequency of 44.1kHz (352.8kHz) so that a
sine wave output of 991Hz is realized. For production
testing, the output of the DAC goes to an I to V converter,
then to a programmable gain amplifier to provide gain at
lower signal output test levels, and then through a 40kHz
low pass filter before being fed into an analog type distortion
analyzer. Figure 1 shows a block diagram of the production
THD+N test setup.
For the audio bandwidth, THD+N of the PCM63P is essen-
tially flat for all frequencies. The typical performance curve,
“THD+N vs Frequency,” shows four different output signal
levels: 0dB, –20dB, –40dB, and –60dB. The test signals are
derived from a special compact test disk (the CBS CD-1). It
is interesting to note that the –20dB signal falls only about
10dB below the full scale signal instead of the expected
20dB. This is primarily due to the superior low-level signal
performance of the dual-DAC Colinear architecture of the
PCM63P.
In terms of signal measurement, THD+N is the ratio of
DistortionRMS + NoiseRMS / SignalRMS expressed in dB. For
the PCM63P, THD+N is 100% tested at all three specified
output levels using the test setup shown in Figure 1. It is
significant to note that this test setup does not include any
output deglitching circuitry. All specifications are achieved
without the use of external deglitchers.
Dynamic Range
Dynamic range in audio converters is specified as the measure
of THD+N at an effective output signal level of –60dB
referred to 0dB. Resolution is commonly used as a theoretical
measure of dynamic range, but it does not take into account
the effects of distortion and noise at low signal levels. The
ANALOG OUTPUT
INPUT CODE
(20-bit Binary Two’s Complement)
LOWER DAC CODE
(19-bit Straight Binary)
+Full Scale
+Full Scale – 1LSB
Bipolar Zero + 2LSB
Bipolar Zero + 1LSB
Bipolar Zero
Bipolar Zero – 1LSB
Bipolar Zero – 2LSB
–Full Scale + 1LSB
–Full Scale
011...111
011...110
000...010
000...001
000...000
111...111
111...110
100...001
100...000
111...111 + 1LSB*
111...111 + 1LSB*
111...111 + 1LSB*
111...111 + 1LSB*
111...111 + 1LSB*
111...111
111...110
000...001
000...000
*The extra weight of 1LSB is added at this point to make the transfer function symmetrical around bipolar zero.
TABLE I. Binary Two’s Complement to Colinear Conversion Chart.
UPPER DAC CODE
(19-bit Straight Binary)
111...111
111...110
000...010
000...001
000...000
000...000
000...000
000...000
000...000
®
5 PCM63P
5 Page | ||
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| PDF Descargar | [ Datasheet PCM63P-J.PDF ] | |
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