CXA1797

Manufacturer Part NumberCXA1797
DescriptionDolby B-C Type Noise Reduction System with Recording Equalizer Amplifier
ManufacturerSONY [Sony Corporation]
CXA1797 datasheet
 
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Dolby B-C Type Noise Reduction System with Recording Equalizer Amplifier
Description
The CXA1797Q is an audio signal processing LSI
designed for use in cassette decks.
Functions include Dolby B-C noise reduction,
recording equalizer amplifier, meter circuit
(logarithmic), bias control circuit, and playback
switching circuit. Serial control of these functions is
possible.
Features
• Few external parts
• Serial control of each functions possible
• Dolby B-C noise reduction
• Dolby S noise reduction select switch
• Recording equalizer amplifier
• Recording volume control
• Playback input select switch
• Meter circuit (logarithmic wave detection)
• Bias control circuit (left and right independent)
Applications
Cassette decks
This IC is available only to the licensees of Dolby Laboratories Licensing Corporation from whom licensing and applications
information may be obtained.
"Dolby" and the double D symbols are trade marks of Dolby Laboratories Licensing Corporation.
Sony reserves the right to change products and specifications without prior notice. This information does not convey any license by
any implication or otherwise under any patents or other right. Application circuits shown, if any, are typical examples illustrating the
operation of the devices. Sony cannot assume responsibility for any problems arising out of the use of these circuits.
CXA1797Q
64 pin QFP (Plastic)
Absolute Maximum Ratings (Ta=25°C)
• Supply voltage
• Operating temperature Topr
• Storage temperature
• Allowable power dissipation
Recommended Operating Conditions
Supply voltage
Structure
Bipolar silicon monolithic IC
—1—
V
+12
V
CC
(between V
and V
)
CC
EE
–20 to +75
°C
Tstg
–65 to +150
°C
P
1.02
W
D
V
±5.25 to ±6.0
V
CC
E94X42-TE

CXA1797 Summary of contents

  • Page 1

    ... Dolby B-C Type Noise Reduction System with Recording Equalizer Amplifier Description The CXA1797Q is an audio signal processing LSI designed for use in cassette decks. Functions include Dolby B-C noise reduction, recording equalizer amplifier, meter circuit (logarithmic), bias control circuit, and playback switching circuit. Serial control of these functions is possible ...

  • Page 2

    ... R1 —2— 10k 130k 22k 600 22k R60 R59 R58 R57 3.3µ 150 R54 C18 4k R52 1.0µ 8.5k R45 C13 10k R43 4.7µ 100k C12 R41 8k R33 GND 0.068µ C8 0.1µ C7 2.2µ 390p 5.6mH 22k R14 50k 50k R10 R9 CXA1797Q ...

  • Page 3

    ... CXA1797Q ...

  • Page 4

    ... V EE –26dBv I 40kΩ (–25dBm) 147 — — — 147 —4— Description Recording volume 147 input buffer output 6.5k Recording volume output 6.5k 147 V CC VCT Recording input Time constant for the HLS V EE CXA1797Q = 5 ...

  • Page 5

    ... I/O Z (in) Equivalent circuit AC — — — 147 — — 147 O 23.5kΩ VCT —5— CXA1797Q Description V CC Time constant for the LLS V EE Line output 8k 147 Dolby S NR output 12k 147 V CC Dolby S NR input V EE ...

  • Page 6

    ... REC EQ OUT2 I/O Z (in) Equivalent circuit — 50kΩ 147 — — — 8. — —6— Description Recording output 147 V CC Recording equalizer amplifier input VCT cut capacitance V EE Recording equalizer amplifier 147 50k output CXA1797Q ...

  • Page 7

    ... V EE —7— Description V CC Recording bias control voltage 147 setting V EE Recording bias control voltage 147 output Time constant for selecting NR mode Time constant for selecting B/C mode 17k 147 Time constant for selecting S and B/C modes Meter output (sensitivity: 100p 65 mV/dB) 76.6k CXA1797Q ...

  • Page 8

    ... DGND — I — 4k DGND — I — — I 100kΩ —8— CXA1797Q Description Negative power supply (Connect to ground when using a single power supply) Positive power supply V CC Reset signal input (active low) 2.5V DGND Load signal input reference Clock input ...

  • Page 9

    ... V CC — I — —9— Description Recording volume balance adjustment DREF High-frequency gain adjustment of recording equalizer amplifier Peak frequency Q adjustment of recording equalizer amplifier Recording equalizer amplifier gain adjustment Logic power supply (DREF = 1/2 DREF (DV + DGND CAL reference.) DGND DVCC CXA1797Q ...

  • Page 10

    ... 50kΩ 147 I 40kΩ 147 — —10— Description Time constant for selecting RECMUTE mode 17k 147 V CC Recording volume input VCT VCT Playback input V EE Head select output of playback 147 equalizer amplifier CXA1797Q ...

  • Page 11

    ... Description V CC Head select input of playback equalizer amplifier VCT V EE Reference current of recording 147 equalizer amplifier V CC Ground (center capacitance when using a single power supply Reference current V +1.25V CXA1797Q ...

  • Page 12

    ... IN pin and then measure the relative deviation from NORM-NS, 315 Hz mode. METAL-tape, NORM-speed mode Input a 12 kHz signal (-20 dB level down) to the REC EQ IN pin and then measure the relative deviation from NORM-NS, 315 Hz mode. —12— CXA1797Q = Specifications Unit Min ...

  • Page 13

    ... With no signal, measure the noise using the "A"-WGT filter. (The measured value is indicated as the relative value compared to the reference level.) NORM-tape, NORM-speed mode With no signal, measure the DC offset voltage of the REC OUT pin. —13— CXA1797Q Specifications Unit Min. Typ. Max. –6.2 –5.2 –4.2 dB –0.5 1 ...

  • Page 14

    ... Input a 1 kHz signal and set the input level so that the THD is 1%. (Measure the distortion when the output is +2 dBv.) REC-VOL = 2.0 V, REC-BAL = 2 2.7 kΩ Input a 1 kHz, -10 dBv signal (reference input level) and measure the distortion. (Measure the distortion as THD + N.) —14— CXA1797Q Specifications Unit Min. Typ. Max. — –88.0 –80.0 dB 4.6 6 ...

  • Page 15

    ... Alternately input a 1 kHz, -18 dBm signal to the DOLBY PB IN pin and measure the channel crosstalk. (Use a 1 kHz BPF.) METER ON, REC mode Input a 1 kHz, -26 dBv signal to the REC IN pin and measure the output DC voltage at the METER pin. —15— CXA1797Q Specifications Unit Min. Typ. Max. 80.0 83.0 — dB – ...

  • Page 16

    ... DC voltage of the BIAS OUT pin. METAL mode Set the external feedback resistance to 56 kΩ, 11 kΩ, 11 kΩ, and 11 kΩ, and measure the output DC voltage of the BIAS OUT pin. —16— CXA1797Q Specifications Unit Min. Typ. Max. 2.75 3.05 3.35 V 1.85 2.15 2. ...

  • Page 17

    ... Input a 1 kHz, +10 dB signal to the REC IN pin and measure the distortion. (Measure the distortion as THD + N.) REC, Dolby B mode Input a 1 kHz, +10 dB signal to the REC IN pin and measure the distortion. (Measure the distortion as THD + N.) —17— CXA1797Q Specifications Unit Min. Typ. Max. — –6.0 — ...

  • Page 18

    ... With no signal, measure the deviation in the output DC offset voltage at the REC OUT pin when switching from NR off mode to C type mode. ViH ViL fck tw tsu(DATA CLK) tH(CLK DATA) tw(DATA) ts(LATCH DATA) tH(CLK LATCH) tw(XRST) —18— CXA1797Q Specifications Unit Min. Typ. Max. — 0.08 0.3 % 60.0 61.0 — dB — –79 –70 dB — ...

  • Page 19

    ... V30 V29 V28 V27 V26 NORMAL METAL OUT1 IN1 OUT1 REC IN1 OUT1 TCL1 TCH1 OUT1 GND —19— CXA1797Q GND 10k OUT1 3.3µ R103 S59 METER C43 10k 4.7µ R101 S57 TC B/C C41 10k 4.7µ R99 S55 TC NR 10k C39 3 ...

  • Page 20

    ... CXA1797Q ...

  • Page 21

    ... Description of Operation 1. Logic Usage The CXA1797Q is controlled by 11-bit serial data. Name D1 SPEED D2 METAL A/B D5 METER D6 PB/REC D7 LMUTE D8 RMUTE D9 BC/S (Note 1) D10 B/C D11 NR ON/OFF Note 1) S mode takes precedence over other noise reduction modes. (When turning noise reduction off, select BC mode.) Note 2) All data is initialized to "1" when a reset is executed. ...

  • Page 22

    ... Timing Chart of 11-bit Serial Data Interface CLK 3.5V DATA 1.5V t SLD LATCH 1.5V CLK D10 DATA LATCH XRESET 3.5V 1. SDK HCD D1 3.5V t HLC t HCL D11 3.5V 1.5V 1. —22— CXA1797Q ...

  • Page 23

    ... Low-frequency boost (external) and DGND) applied to this pin DGND)/2 is applied to this pin or when it is open DGND)/2 is applied to this pin or when it is open.) CC GP/ Frequency (Hz) —23— + DGND)/2 is applied to this pin or when it is RECCAL CXA1797Q ...

  • Page 24

    ... In addition, these functions can be controlled directly by applying voltage from an external source. (In this case, the capability to drive 17 kΩ impedance is required.) 6. Meter circuit The CXA1797Q meter circuit is a logarithmic detector. The circuit has a sensitivity of 65 mV/dB and is designed to generate 2.8 V when the reference signal is input. ...

  • Page 25

    ... Output level (dB) REC EQ frequency response 100 1k Frequency (Hz) 14 ±5. NORM Tape—NORM SPEED 12.0 0dB = —4dBV THD 10.0 8.0 6.0 4.0 2.0 0 100 8 12 —25— CXA1797Q 100k 10k REC EQ load characteristics f=315Hz f=1kHz 500 1k 5k 10k 50k Load resistance ( ) 100k ...

  • Page 26

    ... GH = 2.5V –10 10 100 1k Frequency (Hz) FQ CAL frequency response ±5. NORM Tape—NORM SPEED REC CAL and GH CAL: open 0dB = 315Hz, —24dBV CAL = 5.0V 0 –10 10 100 1k Frequency (Hz) —26— 100k 10k 100k 10k FQ CAL = 0V FQ CAL = 2.5V 100k 10k CXA1797Q ...

  • Page 27

    ... Output level vs. FQ CAL voltage 8 NORM Tape—NORM SPEED REC CAL, GH CAL = 2.5V 6.0 0dB = REC CAL, FQ CAL, GH CAL: open 4.0 2.0 0 –2.0 –4.0 –8.0 0 1.0 2.0 FQ CAL pin voltage (V) —27— 3.0 4.0 315Hz 3kHz 8kHz 12kHz 3.0 4.0 5 =±5.5V EE —20dB (at 315Hz, —4dBv) 315Hz 3kHz 8kHz 12kHz 3.0 4.0 5.0 CXA1797Q 5.0 ...

  • Page 28

    ... REC balance control voltage (V) REC VOL total harmonic distortion ±5. REC LEVEL: 2.0V 0dB = –10dBV f = 1kHz 1.0 0.1 0.01 –8 –4 0 Output level (dB ±5. NORM Tape—NORM SPEED REC CAL, FQ CAL, GH CAL = 2.5V 0dB = REC LEVEL = 5.0V BALANCE = 2.5V Output for –10dBv input —28— CXA1797Q ...

  • Page 29

    ... NR B type total harmonic distortion 2 Encode Mode 0dB = Dolby Level 1.0 0.5 0.2 0.1 0.05 f=1kHz f=10kHz 0.02 0.01 – —29— CXA1797Q –60dB –50dB –40dB –30dB –20dB –10dB 0dB 500 10k Frequency (Hz) = ±5.5V f=100Hz Output level (dB) ...

  • Page 30

    ... Rejection on Split Supply =± 5. off encoding mode 0 NR off decoding mode NR B encoding mode NR B decoding mode – encoding mode $ NR C decoding mode –20 – –40 –50 –60 100 200 10k —30— CXA1797Q $ $ $ $ $ $ 500 10k Frequency (Hz) ...

  • Page 31

    ... SONY CODE EIAJ CODE JEDEC CODE 64PIN QFP(PLASTIC) 23.9 ± 0.4 + 0.4 20.0 – 0 0.15 0.4 – 0.1 2.75 – 0.15 ± 0.12 PACKAGE STRUCTURE PACKAGE MATERIAL LEAD TREATMENT QFP–64P–L01 LEAD MATERIAL QFP064–P–1420 PACKAGE WEIGHT —31— + 0.1 0.15 – 0.05 0.15 + 0.2 0.1 – 0.05 + 0.35 M EPOXY RESIN SOLDER/PALLADIUM PLATING COPPER /42 ALLOY 1.5g CXA1797Q ...