Ordering number : ENN6657
Monolithic Linear IC
LA4802T
Headphone Stereo Power Amplifier
Overview
The LA4802T is a headphone stereo power amplifier for
portable CD and MD players. It features a high signal-to-
noise ratio, a high ripple rejection ratio, low distortion,
and low current drain.
Package Dimensions
unit: mm
3262-MSOP20
[LA4802T]
5.2
Functions
•
•
•
•
Headphone stereo power amplifier
Power switch
Muting switch
Beep tone function control input pin (The beep tone
function can be used regardless of whether the mute
function is on or off.)
20
11
4.4
6.3
1
(0.35)
0.5
0.2
10
0.125
High signal-to-noise ratio (100 dB typical at 7.5 µV)
High ripple rejection ratio (70 dB typical)
Low current drain (950 µA typical)
On-chip bass compensation circuit
(Compensates for bass frequency attenuation due to the
output capacitors and achieves flat frequency
characteristics.)
• Ultraminiature package (MSOP-20)
•
•
•
•
0.08
(0.65)
0.85max
Features
SANYO: MSOP20
Specifications
Maximum Ratings
at Ta = 25°C
Parameter
Maximum supply voltage
Allowable power dissipation
Operating temperature
Storage temperature
Symbol
V
CC
max
Pd max
Topr
Tstg
When mounted, Ta = 80°C
Conditions
Ratings
4.5
375
–20 to +80
–40 to +150
Unit
V
mW
°C
°C
Any and all SANYO products described or contained herein do not have specifications that can handle
applications that require extremely high levels of reliability, such as life-support systems, aircraft’s
control systems, or other applications whose failure can be reasonably expected to result in serious
physical and/or material damage. Consult with your SANYO representative nearest you before using
any SANYO products described or contained herein in such applications.
SANYO assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other
parameters) listed in products specifications of any and all SANYO products described or contained
herein.
SANYO Electric Co.,Ltd. Semiconductor Company
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN
72502RM (OT) No. 6657-1/10
0.5
LA4802T
Operating Conditions
at Ta = 25°C
Parameter
Recommended supply voltage
Operating supply voltage range
Recommended load resistance
Symbol
V
CC
V
CC
op
R
L
Conditions
Ratings
2.4
1.8 to 3.6
16 to 32
Unit
V
V
Ω
Electrical Characteristics
at Ta = 25°C, V
CC
= 2.4 V, f
IN
= 1 kHz, R
L
= 16
Ω
Item
Quiescent current
Symbol
I
CCO
1
I
CCO
2
I
CCO
3
Operating current drain
Voltage gain
Channel balance
Output power
Total harmonic distortion
Output noise voltage
Crosstalk
Ripple rejection ratio
Peak output voltage
Muting attenuation
Power on voltage sensitivity
Power off voltage sensitivity
Mute on voltage sensitivity
Mute off voltage sensitivity
Boost on voltage sensitivity
Boost off voltage sensitivity
I
CC
1
VG
∆VG
P
O
THD
V
NO
CT
SVRR
V
O
BEEP
V
OFF
V
1 ON
V
1 OFF
V
20 ON
V
20 OFF
V
4 ON
V
4 OFF
I
CC
2
THD2
V
NO
2
CT2
SVRR2
Conditions
Current when ST is off (with L.B. on and muting off)
Current when muting is on (with ST on and L.B. on)
Current when ST is on (with L.B. on and muting off)
P
O
= 0.1 mW (With 2 channels driven)
V
O
= –10 dBm
V
O
= –10 dBm
THD = 10%
V
O
= –8 dBm, 20 kHz LPF
Rg = 10 kΩ, IHF A
T
UN
1kHz, V
O
= –10 dBm
fr = 100 kHz, Vr = –20 dBm, T
UN
100Hz
V
IN
= 2.4 Vp-p, f = 1 kHz, MUTE OFF
THD = 1%, T
UN
1kHz
Power on threshold voltage
Power off threshold voltage
Muting on threshold voltage
Muting off threshold voltage
Boost on threshold voltage
Boost off threshold voltage
1.4
1.4
0.5
0.5
70
60
1.0
–100
1.6
0.5
6.8
–1
25
Ratings
min
typ
0.05
530
950
3.2
7.8
0
38
0.03
–100
80
70
2.7
–120
0.1
–90
max
1
900
1500
3.7
8.8
+1
Unit
µA
µA
µA
mA
dB
dB
mW
%
dBm
dB
dB
mV
dB
V
V
V
V
V
V
Ta = 25°C, V
CC
= 2.7 V, f
IN
= 1 kHz, R
L
= 47 kΩ (Characteristics when used as a line output), L.B OFF
Operating current drain
Total harmonic distortion
Output noise voltage
Crosstalk
Ripple rejection ratio
V
O
= 0 dBm (With 2 channels driven)
V
O
= 0 dBm, 20 kHz LPF
Rg = 10 kΩ, IHF A
T
UN
1kHz, V
O
= –10 dBm
fr = 100 kHz, Vr = –20 dBm, T
UN
100Hz
80
65
1.5
0.005
–100
90
78
2.0
0.05
–90
mA
%
dBm
dB
dB
Switch Threshold Voltages and Pin Influx Currents
• Standby switch (pin 1)
Pin influx current (µA)
H : IC ON
L : IC OFF
120
100
80
60
40
20
0
0
L
H
1
2
V
1
(V)
3
4
5
• Mute switch (pin 20), boost switch (pin 4)
Pin influx current (µA)
H : MUTE ON, L. B OFF
L : MUTE OFF, L. B ON
40
30
20
L
H
0
0
1
2
3
V
20
, V
4
(V)
4
5
No. 6657-2/10
LA4802T
Notes on the Beep Tone Output Function
• This function provides a beep tone output under control of the system microcontroller.
• The beep tone can be provided regardless of the on/off state of the muting function.
• The recommended beep input signal level is a square wave with V
IN
= 2.4 Vp-p. When the muting function is off, the
beep tone output, V
O
BEEP, will be 2.7 V rms, and when muting is on, the output will be 1.3 Vrms.
Notes on the Muting Time
• The muting on time and the muting off time can be modified by changing the value of the external capacitor C4
connected to pin 6. The recommended value for C4 is 1 µF. With lower values, impulse noise levels will increase.
• The on/off times will change as shown below when the value of C4 is varied.
C4
0.1 µF
0.47 µF
1 µF
On time
0.2 ms
1 ms
2 ms
Off time
9 ms
40 ms
80 ms
• We recommend operating the mute switch at the same time as the power on/off switch (pin 1) to minimize impulse
noise at power on and off.
VCC
MUTE S. W
PWR S. W
A13553
Notes on the Bass Compensation Circuit
• When the headphone load is connected to the output, the low frequencies will be attenuated due to the output
capacitors. This circuit compensates for that attenuation and creates frequency response characteristics that are close
to flat.
• This function can be turned on or off from pin 4. When used as a line output, the load will be less than 16
Ω,
and the
bass frequency characteristics will be somewhat increased. Therefore we recommend leaving the bass compensation
circuit off in this case.
VG — f
2
+
Voltage gain, VG — dB
0
–2
–4
–6
–8
–10
–12
–14
Load terminal
A13554
–16
10
No
bas
Output pin
s co
mp
100
ens
a
tion
sc
Bas
omp
en
n ap
satio
plie
d
1000
1k
10k
Frequency, f — Hz
No. 6657-3/10
LA4802T
Block Diagram and Test Circuit
Vcc
Vcc
ON
PW SW
MT SW
ON
1
OFF
PW SW
IN A
MT SW
OUT A
20
OFF
C1
+
2
10kΩ
10kΩ
19
+
C17
0.1µF
10Ω
C18
10µF
220µF
16Ω
A
3
Vcc
R1
51kΩ
C3
ON
BST NF
A
Pre
GND
Boost
SW
18
+
0.47µF
C16
Vref A
OFF
+
4
Boost SW
PWR
GND
17
1µF
C2
IN B
OUT B
+
5
10kΩ
10kΩ
16
+
C14
0.1µF
C15
10µF
C4
Pre GND
1µF
C5
+
B
6
BST NF
B
220µF
R2
10Ω
16Ω
MUTE C
Vref
OUT A
15
+
0.47µF
C13
Vref B
+
Vcc
7
Vref
OUT B
Vref A
L.B C
14
22µF
C12
+
+
-
Vcc
220µF
C6
+
8
Vref B
13
Vref
CONT C
+
C11
2.2µF
C10
22µF
Beep
IN
C7
+
9
Beep
R.F
CONT
12
+
0.1µF
R.F
OUT
2.2µF
C8
+
10
R.F
11
+
C9
4.7µF
4.7µF
* Package : MSOP-20
Top view
No. 6657-4/10
LA4802T
External Components (Values in parentheses are recommended values.)
• C1, C2 (1 to 10 µF)
Input coupling capacitors.
• C3 (0.47 to 2.2 µF)
Boost switch on/off impulse noise reduction capacitor.
• C4 (1 µF)
Mute switch on/off impulse noise reduction capacitor.
• C5, C6 (10 to 22 µF)
Reference bias (V
REF
) decoupling capacitors.
• C7 (0.1 to 1 µF)
Beep input coupling capacitor. Be careful not to attenuate the beep tone signal.
• C8, C9 (2.2 to 4.7 µF)
Ripple filter capacitors.
• C10 (2.2 to 4.7 µF)
Reference bias (V
REF
) decoupling capacitors.
• C11 (1 to 2.2 µF)
Boost switch on/off impulse noise reduction capacitor.
• C12 (220 µF)
Power supply line decoupling capacitor.
• C13, C16 (0.47 µF)
Low pass filter capacitor in the bass boost circuit. The amount of bass boost depends on the value of this capacitor.
• C14, C17 (0.1 µF)
Output oscillation prevention capacitors. We recommend using Mylar capacitors. Since the oscillation stability
varies depending on the PCB layout and other factors, we recommend a value of at least 0.1 µF for these capacitors.
• C15, C18 (220 to 470 µF)
Output capacitors. Low band attenuation increases with lower capacitances.
• R1 (24 to 51 kΩ)
Smoothing resistor for the boost switch on/off transition. Note that using a smaller value will increase the idling
current when the boost switch is off.
• R2, R3 (10
Ω)
Output oscillation prevention resistors.
No. 6657-5/10
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