Datasheet BA3880AS, BA3880AFS Datasheet (ROHM)

BA3880AS / BA3880AFS

Audio ICs

High-definition sound processor

BA3880AS / BA3880AFS

The BA3880AS and BA3880AFS are sound processor ICs that perform phase and harmonic compensation on audio signals to accurately reproduce the "rise" section of audio signals that determines the characteristics of the sound, and thus reproduce the original recording as naturally as possible.

Applications

!!!!

Component stereo systems, radio cassette players, car stereo systems, televisions, VCRs, and active speakers.

Features

!!!!

1) Correct distortion in the rising section of audio signals that results from miss-matched speakers and amplifiers, and reproduces the original sound faithfully.

2) To allow application with all types of speakers and sources, the clarity can be adjusted using DC control.

3) DC control provided for selection of either processor mode or bypass mode.

4) Bass boost fixed internally to 4dB.

Block diagram

!!!!

BA3880AS

1

MIXL

2

VCAL

3

CC

V

4

DEFL

5

DETL

6

GND

7

DETR

8

DEFR

CTL

9

10

VCAR

11

MIXR

CTL

VCA

+

HI MID LO

+

−

+

HI

+

MID

+

BA3880AFS

CTL

HPF

24

DETL

23

22

DEFR

21

CC

V

20

VCAL

19

MIXL

18

OUTL

17

INL

16

15

APFL

14

HPFL

13

LPFL

1

22

OUTL

21

INL

20

APFL

HPF

19

LPF

HPF

LO

HPFL

18

LPFL

17

BIASC

16

LPFR

15

HPFR

APFR

14

13

INR

OUTR

12

GND

DETR

DEFR

CTL

VCAR

MIXR

OUTR

INR

APFR

HPFR

LPFR

BIASC

2

CTL

3

VCA

LO

− +

+ +

+

HI

MID

LO

+

−

LPF

HPF

LPF

VCA

+

HI

MID

+

4

5

6

7

8

9

10

11

12

Audio ICs

Absolute maximum ratings

!!!!

Parameter Power supply voltage Power dissipation Operating temperature Storage temperature

Reduced by 10mW for each increase in Ta of 1°C over 25°C.

∗

Recommended operating conditions

!!!!

(Ta = 25°C)

Symbol Limits Unit

CC

V

Pd

Topr

Tstg

11

∗

1000

−40~+85

−55~+125

BA3880AS / BA3880AFS

V

mW

°C °C

Parameter Power supply voltage V

Electrical characteristics

!!!!

(unless otherwise noted, Ta = 25°C, V

Parameter Circuit current Voltage gain 1 Voltage gain 2 Voltage gain 3 Voltage gain 4 Voltage gain 5 Channel balance Maximum output voltage Output noise voltage 1 Output noise voltage 2 Total harmonic distortion 1 Total harmonic distortion 2 Channel separation Ripple rejection ratio

∗Note : When VCTL = 9V, the IC is in bypass mode (through operations).

When V

CTL = 4.5V, the IC is in processor mode (enhance operations) with minimum definition level. CTL = 0V, the IC is in processor mode (enhance operations) with maximum definition level.

When V

Symbol Limits Unit

CC

Symbol

I

CC

G

V1

G

V2

G

V3

G

V4

G

V5

5.4~10.8 V

CC

= 9V, fIN = 1kHz, VIN = 200mVrms, Rg = 600Ω, RL = 100k Ω and V

Min.

3.9

Typ.

5.9

−2.0

−2.5

−1.0

9.0

−0.5

1.0

11.0

−

4.0

CB −2.0 0 2.0 dB

V

NO1

V

NO2

THD THD

OM

2.0 2.3 − Vrms THD

− 210µVrms

− 16 70 µVrms

1

− 0.005 0.05 % 400Hz~30kHz BPF,

2

− 0.04 0.4 % 400Hz~30kHz BPF CS −−67 −60 dB RR 60 68 − dB

Max. Unit Conditions

11.8

0

2.0

1.5

4.0

13.0

−

mA

dB dB

dB dB dB

IN

=

0Vrms

V V

CTL

= 9V

fIN = 10kHz

IN

= 10kHz, V

f

IN

= 50Hz

f fIN = 10kHz, V

=

1%

Rg = 0Ω, DIN AUDIO, V Rg = 0Ω, DIN AUDIO

VIN = 1Vrms Rg = 0Ω, fR = 100Hz, VR = 100mVrms

CTL

= 0V

CTL

= 4.5V)

CTL

= 9V

V

CTL

=

9V

Audio ICs

Measurement circuit

!!!!

BA3880AS

470p

6800p

BA3880AS / BA3880AFS

1 22

MIXL

2 21

VCAL

OUTL

INL

4.7µ

V

4.7µ

THD

100k

A

9V

9V 4.5V

47µ

3 20

CC

V

0.1µ 4 19

1µ

4.7µ

1µ

470p

6800p

DEFL

DETL

5 18

GND

6 17

7 16

DETR

8 15

DEFR

9 14

CTL

10 13

VCAR

11 12

MIXR

BA3880AS

Fig.1

APFL

HPFL

LPFL

BIASC

LPFR

HPFR

APFR

INR

OUTR

0.01µ

0.068µ

0.01µ

600

47µ

4.7µ

600

4.7µ

V

(Units) R : Ω

THD

C : F

100k

Audio ICs

BA3880AFS

9V 4.5V

THD

100k

BA3880AS / BA3880AFS

1 24

GND

2 23

4.7µ

1µ

6800p

470p

4.7µ

V

DETR

3 22

DEFR

4 21

CTL

VCAR

5 20

6 19

MIXR

OUTR

7 18

INR

8 17

BA3880AFS

DETL

DEFL

V

VCAL

MIXL

OUTL

INL

4.7µ

1µ

0.1µ

CC

6800p

470p

47µ

9V

A

4.7µ

V

THD

100k

600

4.7µ

47µ

APFR

9 16

0.01µ HPFR

10 15

LPFR

11 14

0.068µ

12

BIASC

Fig.2

APFL

HPFL

LPFL

600

0.01µ

13

0.068µ

(Units) R : Ω

C : F

BA3880AS / BA3880AFS

Audio ICs

Circuit operation

!!!!

The BA3880AS and BA3880AFS high-definition sound processor system ICs treat the amplifiers and speakers as a total audio systems, and perform signal processing at the amplifier input stage to accurately reproduce the rise sections of audio signals that determine the characteristics of sound, and ensure that the replayed audio is as close to the original sound and as natural sounding as possible.

Problems relating to playback of sound on audio systems. With naturally-generated sound, high-frequency harmonic components generally occur first, followed by the fundamental frequency components. This also applies to the attack section of the sound that characterizes many musical instruments. It is the amplitude component that gives form to the frequency component and envelope at the rising point of sound, and this expresses the characteristics of the sound. Therefore, when replaying audio on audio playback systems, it is extremely important that the rise section of the signal be expressed accurately with respect to the original sound. However, there is inevitable mismatching between the speakers and amplifiers in current audio systems. Solid-state power amplifiers use negative feedback techniques and operate off a fixed voltage supply, but as speakers are a current element, mismatching in the system inevitably occurs. In addition, the speaker impedance characteristics are strongly influenced by the electrical reactance of the voice coil, and the mechanical reactance of the cone assembly. As a result of this, distortion is generated in the rising sections of audio signals, causing phase shift in the reproduced sound. In addition, impedance increases in the treble region which reduces the speaker amplitude and reduces the harmonic component, and as a result there is a tendency to masking of large mid-frequency signal components that follow, and this makes it difficult to reproduce the rising sections of the sound.

Operating principle

!!!!

To solve the problems described above, the BA3880AS and BA3880AFS perform the audio signal processing described below.

Phase shift compensation

BASS MIDDLE TREBLE

20 150 2.4k 20k f (Hz)

The input signal is separated into three regions: bass (20Hz to 150Hz), middle (150Hz to 2.4kHz) and treble (2.4kHz to 20kHz). These regions are then joined again with the middle and treble regions phase shifted −180° and −360 respectively with respect to the bass signal. This phase shift adjusts the delay time characteristic for each band and minimizes the distortion of the rising section of the audio signal.

Amplitude compensation (harmonic compensation) To maintain appropriate auditory balance for the treble region that is made up of harmonic components, a high-speed detector and high-performance VCA circuit are used for amplitude control of the treble component. The amount of compensation is determined from a calculation performed based on the DC level input to the CTL pin, and the DC level detected from the input signal. The internal control signal obtained from this calculation compensates the amplitude of the treble component input to the VCA. This amplitude compensation recovers the harmonic component, and improves the reproduction clarity (definition level) of instruments and vocals.

°

BA3880AS / BA3880AFS

Audio ICs

Bass boost To maintain good balance with the dynamically changing treble component, the bass component is boosted. The bass boost is fixed at 4dB (typ.) internally, and cannot be adjusted.

Mode switch The DC voltage on the CTL pin can be used to switch the IC between processing mode and bypass mode. When processing mode is selected, the audio signal is enhanced using the compensation circuits described above before being output. When bypass mode is selected, the signal bypasses all of the compensation circuits, and only passes through a buffer amplifier before output.

External components The frequency characteristic in processing mode with maximum definition level is given below.

GAIN

C1

C2

C1: External capacitor

connected between the VCA and MIX pins (6800pF in the application circuit).

C2: External capacitor

connected between the OUT and MIX pins

BASS BOOST

LARGE

SMALL

LARGE SMALL

DEFINITION LEVEL

(470pF in the application circuit).

FREQUENCY

As indicated in the diagram, capacitors C1 and C2 determine the treble component cutoff frequency. By varying the values of these components, the frequency characteristic can be changed as indicated by the dotted line in the diagram. This varies the balance of the harmonic component, and is an important factor in determining the tone quality.

Control table

Item Threshold level Mode setting Definition level

V

CC

0.64 ×

V

CC

V

CTL

0.57 ×

V

CC

0V (GND)

Recommended setting range for bypass mode

0.75 ×

V

CC

0.5 ×

V

CC

Recommended setting range for processor mode

Min. (1dB Typ.)

Max. (11dB Typ.)

Audio ICs

Application example

!!!!

BA3880AS

BA3880AS / BA3880AFS

V

CC

GND

V

CTL

47µ

470p

68000p

470p

0.1µ

1µ

4.7µ

1µ

MIXL

VCAL

V

DEFL

DETL

GND

DETR

DEFR

CTL

VCAR

10

MIXR

11

0.01µ

0.068µ

0.01µ

4.7µ

L−ch OUTPUT

L−ch INPUT

47µ

R−ch INPUT

R−ch OUTPUT

OUTL

1

2

CC

3

4

5

6

7

8

9

VCA

CTL

VCA

+

HI MID LO

+

−

+

HI MID LO

+

HPF

LPF

HPF

22

INL

21

APFL

20

HPFL

19

LPFL

18

BIASC

17

LPFR

16

HPFR

15

APFR

14

INR

13

OUTR

12

Fig.3

(Units) R : Ω

C : F

Audio ICs

BA3880AFS

BA3880AS / BA3880AFS

V

CTL

R−ch OUTPUT

R−ch INPUT

0.068µ

0.01µ

47µ

6800p

470p

4.7µ

1µ

GND

DETR

DEFR

CTL

VCAR

MIXR

OUTR

INR

APFR

HPFR

10

LPFR

11

BIASC

12

DETL

1

24

4.7µ

CTL

2

CTL

3

4

5

6

VCA

LO

−

+

HI

MID

+

VCA

7

8

+

9

HPF

+

HI

MID

LO

+

−

23

DEFR

22

V

CC

21

VCAL

20

MIXL

19

OUTL

18

INL

17

16

APFL

1µ

0.1µ

6800p

470p

4.7µ

GND

47µ

V

L−ch OUTPUT

L−ch INPUT

CC

15

LPF

HPF

HPFL

14

LPFL

0.01µ

13

0.068µ

Fig.4

(Units) R : Ω

C : F

BA3880AS / BA3880AFS

Audio ICs

Operation notes

!!!!

(1) Control pin (CTL) The level of the DC voltage applied to the control pin should be in the range 0V to V possible in the region of the threshold voltage. Allow sufficient margin when setting this voltage. (2) Recommended operating range Provided the IC is operated within the operating temperature range and within the recommended operating conditions, the general circuit functions are guaranteed to operate correctly, and there will not be significant changes in the electrical characteristics. (3) Application example Provided the circuit constants in the application example circuit are used, the application circuit should function correctly. However, we recommend that you confirm the characteristics of the circuit in actual use, and take note of the cautionary items described above. If you change the circuit constants, check both the static and transient characteristics of the circuit, and allow sufficient margin to accommodate variations in both the IC and the external components. (4) License The ICs are manufactured under license from BBB Sound Inc. (U.S.A.). A license agreement with BBB Sound Inc. is required to use this component.

Electrical characteristic curves

!!!!

(dB)

DEFINITION LEVEL :

12

10

8

6

4

2

VCC =

=

f

VIN =

9V

10kHz

200mVrms

(dB)

DEFINITION LEVEL :

16

14

12

10

8 6

4 2

V

CC

= 9V

f = 10kHz

CTL

= 0V

V

CC

. Appropriate switching may not be

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

CONTROL VOLTAGE : V

Fig. 3 Definition level vs.

control voltage

External dimensions

!!!!

BA3880AS

19.4±0.3

0.3

±

3.95

0.2

±

3.4

22

1

0.51Min.

1.778

12

11

0.5±0.1

CTL

(V)

(Units : mm)

6.5±0.3

7.62

0°~15°

0.1

±

0.3

−10 −20 −30 −40 −50 −60

0

INPUT VOL TAGE : VIN

Fig. 4 Definition level vs.

input voltage

BA3880AFS

10.0±0.2

24

±0.2

7.8±0.3

5.4

1

±0.1

1.8

0.8

0.11

(dBV)

13

0.36±0.1

SSOP-A24SDIP22

−70 −80

12

0.15±0.1

0.3Min.

0.15