Sanyo LA4550 Specifications

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.

Monolithic Linear IC

2-Channel AF Power Amplifier

for Radio, Tape Recorder Use

Ordering number:ENN1718B

LA4550

SANYO Electric Co.,Ltd. Semiconductor Company

TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN

Features

• Low quiescent current.

• On-chip 2 channels permitting use in stereo and bridge
amplifier applications.

• High output.

• Minimum number of external parts required.
(9 pcs. munimum)

• Good ripple rejection (at steady state).

• Soft tone at the output saturation mode.

• Good channel separation.

• Easy thermal design.

• Small pop noise at the time of power supply ON/OFF.

Specifications

Absolute Maximum Ratings at Ta = 25˚C

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egatlovylppusmumixaMV

noitapissidrewopelbawollA*xamdP 4W

erutarepmetgnitarepOrpoT 57+ot02–

erutarepmetegarotSgtsT 051+ot55–

* With recommended PCB (See sample printed circuit pattern.)

Operating Conditions at Ta = 25˚C

retemaraPlobmySsnoitidnoCsgnitaRtinU

egatlovylppusdednemmoceRV

ecnatsiserdaoldednemmoceRR

egnaregatlovgnitarepOV

xam 31V

CC

CC

L

po 21ot6.3V

CC

V6LTB 8ot4

V9LTB 8

Package Dimensions

unit:mm

3022A-DIP12F

[LA4550]

12

1

0.81

V6oeretS 8ot2

V9oeretS 8ot4

0.5

2.54

5.12

19.4

3.6

7

7.62

6.45

6

3.46

4.26max

3.5

0.51min

1.3

SANYO : DIP12F

0.4

˚C
˚C

9,6V

Ω
Ω
Ω
Ω

21800TN (KT)/O147KI/6215MW, TS No.1718–1/9

LA4550

Operating Characteristics at Ta = 25˚C, V

See specified Test Circuit.

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tnerructnecseiuQoccI

niagegatloVGVV,0=fR

ecnereffiDniagegatloV

rewoptuptuOP

noitrotsidcinomrahlatoTDHTPOWm052=3.05.1%

ecnatsisertupnIir1203kΩ

egatlovesiontuptuOV

noitcejerelppiRrRV,zH001=f,0=gR

klatssorCTCk01=gR Ω V,zHk1=f,

∆ GV

O

ON

Equivalent Circuit Block Diagram

=9V, f=1kHz, Rg=600Ω, RL=4Ω, ( ) : RL=8Ω,

CC

nimpytxam
V9oeretS5103Am
V6oeretS31Am

mBd15–=941535Bd

NI

V,0=fR

V:LTB

V:LTB

0=gR5.00.1Vm

k01=gR Ω 8.00.2Vm

mBd15–=1±Bd

NI

V:oeretS

CC

CC

V:oeretS

CC

CC

%01=DHT,V6=6.00.1W

%01=DHT,V6=5.2W

%01=DHT,V9=6.11.2W

%01=DHT,V9=)1.4(W

Vm051=0484Bd

R

mBd0=0485Bd

O

sgnitaR

tinU

Sample Application Circuit

[Stereo Use]

No.1718–2/9

LA4550

Sample Printed Circuit Pattern Cu foil-reduced board

[BTL Use 1]

[BTL Use 2]

Description of External Parts

C1 (C2) : Feedback capacitor. The low cutoff frequency is determined by the following formula.

fL=

Since this capacitor as well as decoupling capacitor affects the starting time, the capacitor value must be f ix ed
with the necessary low frequency band fully considered.

C3 (C4) : Bootstrap capacitor. The output at low frequencies depends on this capacitor. Decreasing the capacitor value

lowers the output at low frequencies. A capacitor value of 47µF or more is required.

C5 (C6) : Oscillation blocking capacitor. Use a polyester film capacitor that is good in high frequency response and

temperature characteristic. The use of an electrolytic capacitor, ceramic capacitor may cause oscillation to
occur at low temperatures.

1

2πC1Rf

Rf : Feedback resistor
fL : Low cutoff frequency

Continued on next page.

No.1718–3/9

LA4550

Continued from preceding page.

C7 (C8) : Output capacitor. The low cutoff frequency is determined by the following formula.

fL=

To make the low frequency response in the bridge amplifier mode identical with that in the stereo mode, the
capacitor value must be doubled.

C9 : Decoupling capacitor. Used for the ripple f ilter. Since the rejection effect is saturated the capacitor value more

than needed. This capacitor, being also used for the time constant of the muting circuit, affects the starting
time.

C10 : Power source capacitor.

Application Circuits

Voltage gain adjust

· Stereo mode
The voltage gain is determined by on-chip resistor R1 (R2) and external feedback resistor Rf as follows :

VG=20 log [dB]

Any voltage gain can be obtained by e xternal
resistor Rf.

1

2πC7RL

R1

Rf1+R2

fL : Low cutoff frequency
RL : Load resistance

· [BTL 1]
Bridge amplifier 1 mode

Vo1≈ Vi

Vo2≈ – Vi

Vo = Vo1 – Vo2

= Vi

∴VG=20 log =20log [dB]

Assuming R2=R4=50Ω, R1=R3=20kΩ and Rf1=Rf2, the voltage gain is obtained by :

[BTL 2]

R1

R2+R4+Rf1+Rf2

R3

R2+R4+Rf1+Rf2

R1+R3

R2+R4+Rf1+Rf2

Vo

Vi

VG=20 log [dB]

R1

Rf1+R2

R2+R4+Rf1+Rf2

R1+R3

Bridge amplifier 2 mode
The CH1 is a noninverting amplifer and the CH2 is an inverting amplifier. The total voltage gain, being apparently
higher than that of the CH1 by 6dB, is approximately calculated by the following formula.

VG=20log R2/R1+6 (dB)

To reduce the voltage gain, Rf is connected and the following formula is used.

VG=20log R2/Rf+R1+6 (dB)

No.1718–4/9

LA4550

Proper Cares in Using LA4550-Applied Set

1. If the transformer regulation is not as specified, the supply voltage drops momentarily when the motor of an AC­powered set is turned ON. In this case, hum noise may be generated. So, be careful of the transformer regulation.

2. DC muting
To apply DC muting by controlling the NF pin, it is recommended
to use the circuit configuration shown right. The potential at point
(A) is set to 3.5 to 4V.

3. Pop noise
If pop noise generated at the time of power ON/OFF disturbs you, connect a resistor of approximately 620Ω across
the middle point and GND.

4. Slider contact noise of variable resistor
Since the input circuit uses PNP transistors, no input coupling capacitor is required.
However, if slider contact noise of the variable resistor presents any problem, connect a
capacitor in series with input.

Thermal Design

Since the DIP-12F package is such that the Cu-foiled area of the printed circuit board is used to dissipate heat, make the
Cu-foiled area in the vicinity of the heat sink of the IC as large as possible when designing the printed circuit board. The
use of the Cu-foiled area indicated by shading in the above-mentioned sample printed circuit pattern makes it possible
to dissipate more heat. Power dissipation Pd is increased depending on the supply voltage and load. So, it is recom­mended to use the printed circuit board together with the heat sink. The following is a formula to be used to calculate Pd
(for stereo use). For AC power supply, however, it is recommended to actually measure Pd on the transformer of each
set. For bridge amplifier use, Pd is calculated at 1/2 of the load.
(1) DC power supply

2

V

Pd max= + Icco · V

CC

π2R

L

(2) AC power supply

V

CC2

V

CC

: Supply voltage at quiescent mode

(Pd) : Supply voltage at Pd max
VCC1 : Supply voltage at maximum output
r : Voltage regulation V

CC2

Icco : Quiescent current
Supply voltage regulation

π2R

2

L

Pd max= + Icco · V

VCC(Pd)

(For stereo use) ..... (1)

CC

– V

CC1

V

CC1

(Pd) (For stereo use) .............. (2)

CC

where

(Pd)=

V

CC

1+ ×

(1+r) V

r · V

CC1

√2 · π · R

CC1

R

L

Po max

√

L

Example of Heat Sink Mounting Method
The heat sink must be of such a shape as to be able to dissipate heat from the IC plastic area and fin area and is soldered to
the printed circuit board as shown below. For the size of the heat sink, refer to the Pd – T a characteristic. The material of the
heat sink is recommended to be copper or iron which is solderable. It is recommended to apply silicone grease to the IC
plastic area to reduce thermal resistance between the heat sink and the IC plastic area.

No.1718–5/9

LA4550

No.1718–6/9

LA4550

No.1718–7/9

LA4550

No.1718–8/9

LA4550

Proper Cares in Using IC

1. If the IC is used in the vicinity of the maximum ratings, even a slight v ariation in conditions may cause the maximum
ratings to be exceeded, thereby leading to breakdown. Allow an ample margin of v ariation for supply v oltage, etc. and
use the IC in the range where the maximum ratings are not exceeded.

2. Pin-to-pin short
If power is applied when the space between pins is shorted, breakdown or deterioration may occur. When mounting
the IC on the board and applying power, make sure that the space between pins is not shorted with solder, etc.

3. Load short
If the IC is used with the load shorted for a long time, breakdown or deterioration may occur. Be sure not to short the
load.

4. When the IC is used in radios or radio cassette tape recorders, keep a good distance between IC and bar antenna.

5. When making the board, refer to the sample printed circuit pattern.

6. It should be noted that some plug jacks to be used for connecting to the external speaker are such that both poles are
shorted once when connecting.

Specifications of any and all SANYO products described or contained herein stipulate the performance,
characteristics, and functions of the described products in the independent state, and are not guarantees
of the performance, characteristics, and functions of the described products as mounted in the customer's
products or equipment. To verify symptoms and states that cannot be evaluated in an independent device,
the customer should always evaluate and test devices mounted in the customer's products or equipment.

SANYO Electric Co., Ltd. strives to supply high-quality high-reliability products. However, any and all
semiconductor products fail with some probability. It is possible that these probabilistic failures could
give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire,
or that could cause damage to other property. When designing equipment, adopt safety measures so
that these kinds of accidents or events cannot occur. Such measures include but are not limited to protective
circuits and error prevention circuits for safe design, redundant design, and structural design.

In the event that any or all SANYO products(including technical data,services) described or
contained herein are controlled under any of applicable local export control laws and regulations,
such products must not be exported without obtaining the export license from the authorities
concerned in accordance with the above law.

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying and recording, or any information storage or retrieval system,
or otherwise, without the prior written permission of SANYO Electric Co. , Ltd.

Any and all information described or contained herein are subject to change without notice due to
product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification"
for the SANYO product that you intend to use.

Information (including circuit diagrams and circuit parameters) herein is for example only ; it is not
guaranteed for volume production. SANYO believes information herein is accurate and reliable, but
no guarantees are made or implied regarding its use or any infringements of intellectual property rights
or other rights of third parties.

This catalog provides information as of February, 2000. Specifications and information herein are subject
to change without notice.

PS No.1718–9/9