Datenblatt-pdf.com


PCM1750P Schematic ( PDF Datasheet ) - Burr-Brown Corporation

Teilenummer PCM1750P
Beschreibung Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTER
Hersteller Burr-Brown Corporation
Logo Burr-Brown Corporation Logo 




Gesamt 18 Seiten
PCM1750P Datasheet, Funktion
® PCM1750P
PCM1750U
Dual CMOS 18-Bit Monolithic Audio
ANALOG-TO-DIGITAL CONVERTER
FEATURES
q DUAL 18-BIT LOW-POWER CMOS AUDIO
A/D CONVERTER
q FAST 4.5µs MIN CONVERSION TIME
INCLUDING S/H
q VERY LOW MAX THD+N: –88dB Without
External Adjust
q COMPLETE WITH INTERNAL
REFERENCE AND DUAL S/H FUNCTION
q TWO CO-PHASE SAMPLED, ±2.75V
AUDIO INPUTS
q CAPABLE OF 4X PER CHANNEL
OVERSAMPLING RATE
q RUNS ON ±5V SUPPLIES AND
DISSIPATES 300mW MAX
q COMPACT 28-PIN PLASTIC DIP OR SOIC
DESCRIPTION
The PCM1750 is a low cost, dual 18-bit CMOS
analog-to-digital converter optimized for dynamic sig-
nal applications. The PCM1750 features true co-phased
inputs with an internal sample/hold function for each
channel. The PCM1750 also comes complete with an
internal reference. Total power dissipation is less than
300mW max using ±5V voltage supplies. Low maxi-
mum Total Harmonic Distortion + Noise (–88dB max)
is 100% tested. The very fast PCM1750 is capable
of 4X x audio bandwidth oversampling rates on both
input channels simultaneously, providing greater free-
dom to designers in selecting input anti-aliasing fil-
ters.
PCM1750 outputs serial data in a format that is com-
patible with many digital filter chips and comes pack-
aged in a space saving 28-pin plastic DIP or SOIC.
MSB Adj Left
Offset Adj Left
VIN Left
S OUT Left
SOUT Right
VIN Right
Offset Adj Right
MSB Adj Right
CDAC
S/H Left
CDAC
S/H Right
Reference
Comp
18-Bit SAR
Latch
Latch
Shift Register
Control Logic
Comp
18-Bit SAR
Reference
Clock
Convert
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 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1990 Burr-Brown Corporation
PDS-11084B
PPCrintMed i1n 7U.5S.A0. October, 1993
®






PCM1750P Datasheet, Funktion
THEORY OF OPERATION
OVERVIEW
The PCM1750 is a dual 18-bit successive approximation
CMOS analog-to-digital converter with serial data outputs
designed especially for digital audio and similar applica-
tions. The single-chip converter is fabricated on a 3µ P-well
CMOS process which includes poly-poly capacitors, laser-
trimmable nichrome resistors, and two layers of interconnect
metal. The dual converter employs a switched capacitor
architecture which provides separate, simultaneous S/H
(sample/hold) functions for each input channel. The separate
S/H for each channel results in a desired feature called
co-phase sampling which means that both S/H circuits are
switched at the same time into the HOLD mode to capture
their respective input signals simultaneously. This elimi-
nates phasing errors produced by alternative architecture
ADCs which do not sample the two input channels at the
same time.
Switched binary-weighted poly-poly capacitors are used in
CDAC (capacitive digital-to-analog converter) configura-
tions to form the successive approximation converter sec-
VREF
VIN
CDAC
S1 C1 (MSB)
20PF
S2 C2
10PF
S3 C3
5PF
H1
H2
A1
AZ1
CAZ1
CAZ2
AZ2
AZ3
CAZ3
A2
CAZ4
AZ4
Comparator
Latch Data Out
L
Auto-Zeroed Comparator
P18, P25
VREFIN
+VA (+5V)
P18, P25
600
VREFIN
917
Simplified
VREFIN Circuit
VREF = 2.75V
Ra
C1T
Rb
TDAC
S1T
C2T
S2T
C3T
0 to 120pF
(Code
dependent)
S3T
R1a
13.25k
R1b
500
R2a
R2b
R3a
R 3b
C12T
R12a
S12T
Coff
R12b
100mV
Soff
Roffa
13.25k
Roffb
500
P19, P24
VREFOUT
150k
47k
5k
+VA (+5V)
P16, P27
47k
MSB Adj
.01µF
25k
+VA (+5V)
P15, P28
Off Adj
.01µF
5k
25k
FIGURE 1. PCM1750 Simplified Circuit Diagram.
®
PCM1750
6
Optional External
Adjustment Circuitry

6 Page









PCM1750P pdf, datenblatt
plots are shown at four different input signal levels (with and
without a 4X decimation filter): 0dB, –20dB, –40dB, and –
60dB.
CHANNEL SEPARATION
To test channel separation a 1kHz signal sampled at 192kHz
is placed on one input of the PCM1750 while the other input
is held at 0V. An FFT is performed on the idle (0V) channel
and the result checked to insure that the 1kHz tone is
suppressed by a minimum of 96dB.
GAIN AND OFFSET ERRORS
Initial gain and bipolar offset errors are laser trimmed at the
wafer level and 100% final tested to insure compliance with
the electrical specifications. Bipolar offset errors can be
further reduced to zero by using the optional offset adjust-
ment circuitry shown in the connection diagram (Figure 7).
Gain errors can be adjusted by varying VREF to either
channel of the converter. This is accomplished by either
using an adjustable external reference or by placing buffer
amplifiers with adjustable gain between VREFOUT and
VREFIN as shown in Figure 8a.
INTEGRAL AND DIFFERENTIAL LINEARITY
DC Linearity Testing
The absolute linearity of the PCM1750 is on the order of 15
bits or more as can be seen from the THD versus Frequency
plots in the Typical Performance Curves. Not every code in
the converter must be 15-bit linear to achieve the specified
THD+N performance, but a very high percentage will be
that linear. The same observation also applies to differential
linearity errors in the PCM1750. Because the PCM1750 is
not 100% tested for DC linearity specifications, no mini-
mum or maximum specifications are given for integral or
differential linearity errors.
No Missing Codes Operation
A no missing codes specification is not given for the
PCM1750 for the same reasons as given above. The
PCM1750, however, typically has fewer than 16 codes (less
than 0.01%) missing at a 14-bit resolution level. A 100% no
missing codes specification cannot be maintained above the
12-bit level, although this has very little impact on overall
dynamic performance (THD+N). The few missing codes
that do occur at higher resolution levels are at the bit-2 and
lower major carry transitions of the converter. There are
typically no missing codes (at 14 bits) around the critical
bipolar zero operation zone (±1/8 of full scale range around
bipolar zero or 0V). The critical bipolar differential linearity
error can be reduced from its initial value to zero using the
optional MSB adjustment circuitry shown in the connection
diagram (Figure 7).
REFERENCE
The gain drift of the PCM1750 is primarily due to the drift
associated with the reference. Better drift performance can
be achieved using an external reference like the ones ex-
plained in the applications section (Figures 8b, 8c). The
Typical Performance Curves plot of VREF Output versus
Temperature shows the full range of operation including
initial error and typical gain drift. Pertinent performance
data are found in the electrical specification table.
Reference Bypass
Both P18 and P25 (VREFIN) should be bypassed with a
10µF to 47µF tantalum capacitor. If there are important
system reasons for using the PCM1750 reference externally,
the outputs of P19 and P24 must be appropriately buffered,
and bypassed (see Figure 8).
High
Accuracy
Sine Wave
Generator
Timing
Control
fIN = 1kHz
fs = 192kHz
Low Pass
Filter
Serial Data Left
Serial Data Right
PCM1750
V INL
VINR
FTT
Analyzer
FIGURE 6. PCM1750 Production Test Setup.
®
PCM1750
Parametric
Tester
12

12 Page





SeitenGesamt 18 Seiten
PDF Download[ PCM1750P Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
PCM1750Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTERBurr-Brown Corporation
Burr-Brown Corporation
PCM1750Dual CMOS 18-Bit Monolithic Audio A/D ConverterTexas Instruments
Texas Instruments
PCM1750PDual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTERBurr-Brown Corporation
Burr-Brown Corporation
PCM1750UDual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTERBurr-Brown Corporation
Burr-Brown Corporation

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche