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Multimedia ICs
KARAOKE echo IC
BU9253AS / BU9253FS / BU9255FS
The BU9253AS, BU9253FS and BU9255FS are single-chip ICs that contain all the components needed to configure
a KARAOKE echo system: an A / D and D / A converter, SRAM, LPF, and mixer for mixing source signals. With
these ICs, an echo function can be configured easily and with minimum external components.
•Applications
KARAOKE functions for portable stereo sets, mini com-
ponent stereo sets, video CDs and DVDs, etc.
•Features
1) Echo mixing ratio is adjustable with a DC voltage.
2) A second order LPF can be configured with the
internal amplifier and an attached capacitor and
resistor.
3) Delay time of 131ms. (when fCLK = 357kHz)
4) Internal mute function.
5) Single power supply (5V).
•Block diagram
BU9253FS / BU9255FS
BU9253AS
1
COUNTER
VCC A / D
SRAM
D / A
OSC
2345678
16 15 14 13 12 11 10 9
MIX
123456789
COUNTER
VCC A / D
SRAM
D / A
OSC
16 15 14 13 12 11 10
MIX
18 17
+
–
+
–
+
–
+
–
2
Multimedia ICs BU9253AS / BU9253FS / BU9255FS
•Pin descriptions
BU9253FS / BU9255FS BU9253AS
Pin No. Pin name Function
1GND
2ECHO VR
3BIAS
4DAINT IN
5DAINT OUT
6DALPF IN
7DALPF OUT
8MIX OUT
9MIX IN
10 ADLPF IN
11 ADLPF OUT
12 ADINT OUT
13 ADINT IN
14 VCC
15 MUTE
16 CR
Analog DC bias
DA integrator input
Echo level DC control
DA integrator output
DA LPF input
DA LPF output
Source sound and echo sound
mixing output
Mixing amplifier source sound input
AD LPF input
AD LPF output
AD integrator output
AD integrator input
Vcc
Mute control
Oscillator output
Ground
•Absolute maximum ratings (Ta = 25°C)
Parameter Symbol Limits Unit
Applied voltage VCC 7V
Power dissipation
Pd 500∗1
600∗2
BU9253FS
BU9253AS 500∗1
BU9255FS mW
Operating temperature Topr – 10 ~ + 70 °C
Storage temperature Topr – 55 ~ + 125 °C
Input voltage VIN – 0.3 ~ VCC + 0.3 V
∗1 Reduced by 5.0mW for each increase in Ta of 1°C over 25°C.
∗2 Reduced by 6.0mW for each increase in Ta of 1°C over 25°C.
•Recommended operating conditions (Ta = 25°C)
Parameter
Power supply voltage VCC 4.0 5.5 V5.0
Symbol Min. Typ. Max. Unit
Pin No. Pin name Function
1GND
2ECHO VR
3N.C.
4BIAS
5DAINT IN
6DAINT OUT
7DALPF IN
8DALPF OUT
9MIX OUT
10 MIX IN
11 ADLPF IN
12 ADLPF OUT
13 ADINT OUT
14 ADINT IN
15 VCC
16
17
18
N.C.
MUTE
CR
Ground
Echo level DC control
Internally
Analog DC bias
DA integrator input
DA integrator output
DA LPF input
DA LPF output
Source sound and echo sound
mixing output
Mixing amplifier source sound input
AD LPF input
AD LPF output
AD integrator output
AD integrator input
Vcc
Internally
Mute control
Oscillator output
3
Multimedia ICs BU9253AS / BU9253FS / BU9255FS
•Electrical characteristics (Ta = 25°C, VCC = 5.0V, fCLK = 375kHz, f = 1kHz, VI= - 10dBV, pin 2 = VCC, pin 15 = VCC,
distortion = 400Hz ~ 30kHz filter, output noise voltage : DIN-AUDIO)
*Pin No. are for BU9253FS , BU9255FS and BU9253AS
Parameter
Symbol
Min. Typ. Max. Unit Conditions
VOM2 1.4 1.7 — Vrms
VNO2 — – 90 – 80 dBV
GV2 – 1 0 1 dB
GV1 – 5.6 – 3.5 – 1.4 dB
fC— 375 — kHz
VL0 — 0.7 V
VM1.6 — 2.8 V
VH3.8 — 5.0 V
VOM1 1.4 1.7 — Vrms
VNO1 — – 80 – 60 dBV
THD2 — 0.02 0.1 %
THD1 — 1.5 3 %
ICC — 6 12 mACurrent consumption
Voltage gain 1
Voltage gain 2
Output distortion 1
Output distortion 2
Output noise voltage 1
Output noise voltage 2
Max. output voltage 1
Max. output voltage 2
Mute control
Oscillation frequency
No signal
Delay total gain
IN1→OUT
Through total gain
IN2→OUT, pin2 = ground
Delay side
Through, pin2 = ground
Delay, Rg = 1kΩ
Through side
Rg = 1kΩ, pin2 = ground
Delay, THD = 10%
Through side, THD = 1%
Pin 2 = ground
H mode hold voltage, pin 15 DC
M mode hold voltage, pin 15 DC
L mode hold voltage, pin 15 DC
4
Multimedia ICs BU9253AS / BU9253FS / BU9255FS
•Measurement circuit (for BU9253FS / BU9255FS)
VCC
VCC
100µ
0.1µ
0.01µ
0.012µ
2.2µ
20k
8.2k 1k
2.2µ
IN1
IN2
1k
4700p
10k
100p
39k
MIX
2.2µ
22k
RESISTOR : [Ω]
Unit
CAPACITOR: [F]
OUT
3300p
15k10k
4.7k
0.01µ
0.01µ
22µ
VCC
12345678
0.47µ
D / A
SRAM
A / DOSC
16 15 14 13 12 11 10 9
COUNTER
+
–
+
–
Fig. 1
5
Multimedia ICs BU9253AS / BU9253FS / BU9255FS
• When switching between the muted and unmuted
state (pin 15 (pin 17) L→M→H), the pin 15 (pin 17) M
time should be longer than one SRAM cycle. This is to
assure stability by initializing the SRAM before mode
switching.
Note: Figures in parentheses ( ) are for BU9253AS.
(2) Differences between BU9253AS / FS and BU9255FS
There is a difference regarding the signal stopping for
muting. With BU9253AS / FS, the output from pin 8 (pin
9) is stopped during muting. With BU9255FS, the output
from pin 5 is stopped during muting.
•Application example (for BU9253FS / BU9255FS)
VCC
VCC
100µ
0.1µ
0.01µ
0.012µ
20k
20k
8.2k
IN
4700p
10k
100p
39k
MUTE
MIX
2.2µ
2.2µ
RESISTOR : [Ω]
Unit
CAPACITOR: [F]
OUT
3300p
15k
10k
4.7k
0.01µ
0.01µ
22µ
ECHO LEVEL
12345678
0.47µ
D / A
SRAM
A / D
OSC
16 15 14 13 12 11 10 9
COUNTER
Fig. 2
+
–
+
–
+
+
+
(1) Mute control functions
H Unmuted (operating state)
M Muted
L Clock stop and muted
Pin 15 voltage (pin 17) Mode
6
Multimedia ICs BU9253AS / BU9253FS / BU9255FS
•External dimensions (Units: mm)
SSOP-A16
0.51Min.
0° ~ 15°
7.62
3.95 ± 0.3
1.778
10
9
6.5 ± 0.3
19.4 ± 0.3
18
1
0.5 ± 0.1
3.4 ± 0.2
0.3 ± 0.1
SDIP18
BU9253ASBU9253FS / BU9255FS
0.36 ± 0.10.8
0.11
6.6 ± 0.2
4.4 ± 0.2
6.2 ± 0.31.5 ± 0.1
1
16
8
9
0.15
0.3Min.
0.15 ± 0.1
(3) Setting the echo loop gain
VIN
LPF
R
R
AD SRAM
OdB
VIN VO
VDLY
Recommendable gain
+ 3dB
Recommendable gain
– 6dB
R: R = 1: 1
mix
Echo loop ATT VIN ~ VDLY···A = (A < 1) ∗ With Pin NO. BU9253FS
VIN
VDLY
OUT
DA
2
VR
9
7
8
Fig. 3
+
+
With VOMax being the maximum amplitude of VOat this
time (when the phases, including that of the DLY cir-
cuit, are in alignment):
Thus, maximum allowable input is the value of VOMax
provided the specifications (1 = A). Assuming a feed-
back ratio (A) of 0.7 and a maximum VOUT of 4.0 VP-P,
VIN must be less than 1.2 VP-P.
VOMax. = (1 + A + A2 + ···) VIN =1
1-A
∞
Σ
K = 0 AK· VIN = VIN
