LMC1992.PDF

December 1994

LMC1992 Digitally-Controlled Stereo Tone and Volume

Circuit with Four-Channel Input-Selector

General Description

The LMC1992 is a monolithic integrated circuit that provides

four stereo inputs, bass and treble tone controls, and vol-

ume, balance, and front-rear fader controls. These functions

are digitally controlled through a three-wire communication

interface. All of the LMC1992s functions are achieved with

only three external capacitors per channel. It is designed for

line level input signals (300 mV b 2V) and has a maximum

gain of 0 dB.

The internal design is optimized for external capacitors hav-

ing values of 0.1 m F or less. This allows the use of chip

capacitors for coupling and tone control functions.

Low noise and distortion result from using analog switches

and thin-film silicon-chromium resistor networks in the sig-

nal path.

Volume and fader are at minimum and tone controls are flat

when supply voltage is first applied.

Additional tone control can be achieved using the LMC835

stereo 7-band graphic equalizer connected to the

LMC1992's select-out/select-in external processor loop.

Features

Y Low noise and distortion

Y Four stereo inputs

Y 40 volume levels including mute

Y 20 fader levels

Y All attenuators havea2dBofattenuation per step

Y Front/back fade control

Y External processor loop

Y Only three external components per channel

Y Serial programmable: standard MICROWIRE TM

interface

Y Single supply operation: 6V to 12V supply voltage

Y Protection address (similar to DS8906)

Y DC-coupled inputs

Y Single supply operation

Applications

Y Automotive audio systems

Y Sound reinforcement systems

Y Home entertainmentÐstereo television and music re-

production systems

Y Electronic music (MIDI)

Block and Connection Diagrams

TL/H/10789±2

Order Number LMC1992CCN

See NS Package Number N28B

TL/H/10789±1

Left channel shown. Pin numbers in parentheses are for the right channel.

DNR É is a registered trademark of National Semiconductor Corporation.

COPS TM and MICROWIRE TM are trademarks of National Semiconductor Corporation.

C 1995 National Semiconductor Corporation

TL/H/10789

RRD-B30M75/Printed in U. S. A.

Absolute Maximum Ratings (Notes 1 and 2)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales

Office/Distributors for availability and specifications.

Supply Voltage (V a b GND)

Storage Temperature

b 65 § Cto a 150 § C

Lead Temperature

N Package, Soldering, 10 sec.

a 260 § C

15V

ESD Susceptibility (Note 5)

2000V

Voltage at Any Pin

GND b 0.2V to V a a 0.2V

Pins 9, 10, 11, 19, 20, 21

850V

Input Current at Any Pin (Note 3)

5 mA

Operating Ratings (Notes 1 and 2)

Temperature Range

Package Input Current (Note 3)

20 mA

Power Dissipation (Note 4)

500 mW

T MIN s T A s T MAX

LMC1992CCN

0 § C s T A s 70 § C

Junction Temperature

125 § C

Supply Voltage Range (V a b V b )

6Vto12V

Electrical Characteristics The following specifications apply for V a e 8V, f IN e 1 kHz, input signal applied to

channel 1, volume e 0 dB, bass e 0 dB, treble e 0 dB, and faders e 0 dB unless otherwise specified. All limits T A e T J e

25 § C.

Symbol

Parameter

Conditions

Typical Limit

Units

(Note 6) (Note 7)

(Limit)

I S

Supply Current

27.0 mA (max)

V IN

Input Voltage

Clipping Level (1.0% THD),

2.3

2.0 V rms (min)

Select Out (Pins 8, 22)

V OUT Output Voltage

Clipping Level (1.0% THD),

1.2

0.65 V rms (min)

Outputs (Pins 13, 14, 16, 17)

THD Total Harmonic Distortion All Four Channels

Volume Attenuator at 0 dB, Input Level 0.3 V rms

0.15

0.3 % (max)

Volume Attenuator at b 20 dB, Input Level 0.6 V rms 0.03

0.1 % (max)

E nOUT Output Noise

All Four Channels CCIR/ARM Filter, R S e 0 X

6.5

30.0 m V rms (max)

E nOUT Output Noise

All Four Channels CCIR/ARM Filter, R S e 0 X

5.0

20.0 m V rms (max)

R OUT DC Output Impedance

Pins 8, 22

100

150 X (max)

Pins 13, 14, 16, 17

120 X (max)

R IN DC Input Impedance

Pins 4, 5, 6, 7, 23, 24, 25, 26

M X

Volume Attenuator Range Pins 16, 17; Volume Attenuation at

0101110100X (0 dB); (Absolute Gain) b 1.0 b 1.5

dB (max)

01011000000 (80 dB); (Relative to Attenuation at

80.0

75.0

dB (min)

the 0 dB setting)

Volume Step Size

All Volume Attenuation Settings from 01011001010 2.0

0.7

dB (min)

(60 dB) to 0101110100X (0 dB) (Note 9)

4.3

dB (max)

Channel-to-Channel Volume Fader Attenuation from 1XXX000000

g 0.5

g 1.0

dB (max)

Tracking Error (40 dB) to 1XXX1010X (0 dB)

Fader Attenuation Range Pins 16, 17; Fader Attenuation at

011XXX1010X (0 dB); (Absolute Gain) b 1.0 b 1.5

dB (max)

011XXX00000 (40 dB); (Relative to Attenuation at

38.0

dB (min)

the 0 dB setting)

Fader Step Size

All Fader Attenuation Settings from 011XXX00000

2.0

1.0

dB (min)

(40 dB) to 011XXX1010X (0 dB) (Note 10)

4.5

dB (max)

Volume Attenuator eb 80 dB

Electrical Characteristics The following specifications apply for V a e 8V, f IN e 1 kHz, input signal applied to

channel 1, volume e 0 dB, bass e 0 dB, treble e 0 dB, and faders e 0 dB unless otherwise specified. All limits T A e T J e

25 § C. (Continued)

Symbol

Parameter

Conditions

Typical Limit Units

(Note 6) (Note 7)

(Limit)

Bass Gain Range

f IN e 100 Hz, Pins 14, 16

g 12 g 10.0 dB (min)

Bass Tracking Error

f IN e 100 Hz, Pins 14, 16

g 0.1 g 1.0 dB (max)

Bass Step Size

f IN e 100 Hz, Pins 14, 16

2.0

1.0

dB (min)

(Relative to Previous Level)

3.0

dB (max)

Treble Gain Range

f IN e 10 kHz, Pins 14, 16

g 12

g 10.0 dB (min)

Treble Tracking Error

f IN e 10 kHz, Pins 14, 16

g 0.1

g 1.0 dB (max)

Treble Step Size

f IN e 10 kHz, Pins 14, 16

2.0

1.0

dB (min)

(Relative to Previous Level)

3.0

dB (max)

Frequency Response

b 3 dB

450

kHz

b 0.3 dB (Relative to Signal Amplitude at 1 kHz)

kHz (min)

Channel Separation

V IN e 1.0 V rms

dB (min)

Input-Input Isolation

V IN e 1.0 V rms (Note 8)

dB (min)

PSRR Power Supply Rejection Ratio V a e 8V DC ; 100 mV P-P ,

dB (min)

100 Hz Sinewave Applied to Pin 28

f CLK Clock Frequency 1.0 0.5 MHz (max)

V IN(1) Logic ``1'' Input Voltage 1.3 2.0 V (min)

V IN(0) Logic ``0'' Input Voltage 0.4 0.8 V (max)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed

specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test

conditions.

Note 2: All voltages are specified with respect to ground.

Note 3: When the input voltage (V IN ) at any pin exceeds the power supply voltages (V IN k V b or V IN l V a ) the absolute value of the current at that pin should be

limited to 5 mA or less. The 20 mA package input current limits the number of pins that can exceed the power supply voltages with 5 mA current limit to four.

Note 4: The maximum power dissipation must be de-rated at elevated temperatures and is dictated by T JMAX , w JA , and the ambient temperature T A . The maximum

allowable power dissipation is PD e (T JMAX b T A )/ i JA or the number given in the Absolute Maximum Ratings, whichever is lower. For the LMC1992CCN, T JMAX

e 125 § C, and the typical junction-to-ambient thermal resistance, when board mounted, is 67 § C/W.

Note 5: Human body model; 100 pF discharged through a 1.5 k X resistor.

Note 6: Typicals are at T J e 25 § C and represent the most likely parametric norm.

Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).

Note 8: The Input-Input Isolation is tested by driving one input and measuring the front outputs when the undriven inputs are selected.

Note 9: The Volume Step Size is defined as the change in attenuation between any two adjacent volume attenuation settings. The nominal Volume Step Size is

2 dB.

Note 10: The Fader Step Size is defined as the change in attenuation between any two adjacent fader attenuation settings. The nominal Volume Step Size is 2 dB.