LA4422 Просмотр технического описания (PDF) - SANYO -> Panasonic
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LA4422 Datasheet PDF : 10 Pages
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LA4422
Proper Cares in Bridge Amplifier Application
For bridge amplifier design, take the following into consideration and consult our sales department.
· The LA4422 contains the thermal shutdown circuit which senses generation of abnormal heat attributable to load short,
etc. and stops the internal circuit operation. Thus, breakdown attributable to generatin of abnormal heat is prevented.
· This function operates normally for single IC operation, but the following extraordinary phenomena appear for bridge
operation.
a) Generation of heat of non-inverting, inverting amplifier ICs at the time of output non-clip depends on the radiation
condition of each IC.
b) Generation of heat at the time of output clip is always larger for inverting amplifier IC, which cannot be compensated
even if there is slight difference of radiation condition between two ICs. This is because the output of non-inverter
amplifier IC is clipped and enters completely into the saturation region and Pd (power dissipation) is reduced, while
the output clip of inverting amplifier IC is a mere amplification of output (clip waveform) of non-inverter amplifier
and does not enter into the saturation region and Pd (power dissipation) is held somewhere at the max. level.
c) For this reason, the inverting amplifier IC always generates more heat at the time of output clip. If the radiation
condition is not designed correctly, the thermal shutdouwn circuit of inverting amplifier starts operating earlier.
d) For single IC operation, as above-mentioned, when the thermal shutdown circuit operates, not only the output signal
but also Pd (power dissipation) is reduced so as to minimize generation of heat.
For bridge operation also, if the thermal shutdown circuit of non-inverting amplifier IC operates earlier than the
inverting amplifier IC, generation of heat is minimized similarly to the single IC operation. This is because reduction
of output of input side amplifier (inverting IC) causes reduction of the total output. (It is almost impossible to realize
this state with the normal radiation design.) To the contrary, if the thermal shutdown circuit of inverting amplifier IC
operates earlier, the output of this inverting amplifier IC is reduced, but Pd (power dissipation) is not reduced due to
the drive from the output pin because of bridge connection and operation outside the ASO (area of safety operation)
may occur.
e) Therefore, if the thermal shutdown circuit operates (inverting side) at the time of bridge operation, the above phe-
nomena occur, and if the applied voltage is high, breakdown of the IC beyond the ASO (area of safety operation) may
result.
f) As seen from the above, it is one of the most important factors in the bridge operation circuit design that the radiation
design should be made to prevent the thermal circuit from operating.
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.556–10/10
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