bd5445efv ROHM Co. Ltd., bd5445efv Datasheet - Page 29

• Manufacturer Part Number: bd5445efv
• Description: Analog Input / Single End Output Class-d Speaker Amplifier
• Manufacturer: ROHM Co. Ltd.

●Notes for use
© 2010 ROHM Co., Ltd. All rights reserved.
BD5445EFV
www.rohm.com
1 ) Absolute maximum ratings
2 ) Power supply lines
3 ) Gnd potential （Pin 6, 20, 21, 22, 23）
4 ) Input terminal
5 ) Setting of heat
6 ) Actions in strong magnetic field
7 ) Thermal shutdown circuit
8 ) Shorts between pins and misinstallation
9 ) Power supply on/off (Pin 1, 15, 16, 27, 28）
10 ) Precautions for Speaker-setting
Use of the IC in excess of absolute maximum ratings such as the applied voltage or operating temperature range may
result in IC damage. Assumptions should not be made regarding the state of the IC (short mode or open mode) when
such damage is suffered. A physical safety measure such as a fuse should be implemented when use of the IC in a
special mode where the absolute maximum ratings may be exceeded is anticipated.
As return of current regenerated by back EMF of output coil happens, take steps such as putting capacitor between
power supply and Gnd as a electric pathway for the regenerated current. Be sure that there is no problem with each
property such as emptied capacity at lower temperature regarding electrolytic capacitor to decide capacity value. If the
connected power supply does not have sufficient current absorption capacity, regenerative current will cause the
voltage on the power supply line to rise, which combined with the product and its peripheral circuitry may exceed the
absolute maximum ratings. It is recommended to implement a physical safety measure such as the insertion of a
voltage clamp diode between the power supply and Gnd pins.
Ensure a minimum Gnd pin potential in all operating conditions.
The parasitic elements are formed in the LSI because of the voltage relation. The parasitic element operating causes
the wrong operation and destruction. Therefore, please be careful so as not to operate the parasitic elements by
impressing to input terminals lower voltage than Gnd. Please do not apply the voltage to the input terminal when the
power-supply voltage is not impressed.
Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating
conditions. This IC exposes its frame of the backside of package. Note that this part is assumed to use after providing
heat dissipation treatment to improve heat dissipation efficiency. Try to occupy as wide as possible with heat dissipation
pattern not only on the board surface but also the backside.
Class D power amplifier is High efficiency and low heat generation by comparison with conventional Analog power
amplifier. However, In case it is operated continuously by maximum output power, Power dissipation(Pdiss) may
exceed package dissipation. Please consider about heat design that Power dissipation(Pdiss) does not exceed
Package dissipation(Pd) in average power(Poav). （Tjmax ：Maximum junction temperature=150℃, Ta ：Peripheral
temperature[℃], θja ：Thermal resistance of package[℃/W], Poav：Average power[W], η：Efficiency）
Use caution when using the IC in the presence of a strong magnetic field as doing so may cause the IC to malfunction.
This product is provided with a built-in thermal shutdown circuit. When the thermal shutdown circuit operates, the
output transistors are placed under open status. The thermal shutdown circuit is primarily intended to shut down the IC
avoiding thermal runaway under abnormal conditions with a chip temperature exceeding Tjmax = 150℃.
When mounting the LSI on a board, pay adequate attention to orientation and placement discrepancies of the LSI. If it
is misinstalled and the power is turned on, the LSI may be damaged. It also may be damaged if it is shorted by a
foreign substance coming between pins of the LSI or between a pin and a power supply or a pin and a Gnd
In case power supply is started up, PDX (Pin 10) and MUTEX (Pin 11) always should be set LOW, And in case power
supply is shut down, it should be set LOW likewise. Then it is possible to eliminate pop noise when power supply is
turned on/off. And also, all power supply terminals should start up and shut down together.
If the impedance characteristics of the speakers at high-frequency range while increase rapidly, the IC might not have
stable-operation in the resonance frequency range of the LC-filter. Therefore, consider adding damping-circuit, etc.,
depending on the impedance of the speaker.
Package dissipation: Pd （W） = （Tjmax - Ta）／θja
Power
dissipation:
Pdiss（W） = Poav * （1／η- 1）
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Technical Note
2010.05 - Rev.B