LA4906 Ver la hoja de datos (PDF) - SANYO -> Panasonic
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LA4906 Datasheet PDF : 10 Pages
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LA4906
See the “Standby Function” section elsewhere in this document.
TR1
· External switching transistor. The 2SD1668 (rank S) is recommended.
If the application supports a load resistance RL of 4 Ω, a 2SD1667 (rank S) may be used. A heat sink must be provided
for this transistor, as well as for the IC itself.
D1
· Flywheel diode used to absorb energy from the coil. The SB40-05J, which is a Schottky barrier diode with a low VF, is
recommended.
If the application supports a load resistance RL of 4 Ω, an SB10-05A2 may be used. A heat sink must be provided for
this diode, as well as for the IC itself.
L1
· The Tokin Co., Ltd.-made HP-022Z [180 µH] (or the HP-011Z [200 µH] for 4-Ω applications) is recommended.
2. IC internal characteristics and other notes
Switching regulator
· The LA4906 includes a signal-following self-excited switching regulator to reduce power dissipation. The self-
excitation frequency with no input signal is about 100 kHz.
· To avoid spurious signal interference within the end product case, it is desirable to separate the tuner block from the
amplifier block by as far as possible. When designing the printed circuit board pattern, make the lines associated with
the switching regulator external components as short and as wide as possible.
· To prevent degradation of the LA4906 characteristics, separate the switching regulator external components from the
IC inputs (the input block pattern, the input capacitors, and the beep amplifier capacitor) by at least 1.5 cm.
Standby function
· Pin 21 is the standby switching pin. The amplifier is turned on by applying
a voltage of over 3 V to pin 21 through an external resistor (R1).
· If the standby switch applied voltage will exceed 13.2 V, then the current
flowing into pin 5 must be held to under 500 µA. Use the following
formula to determine the value of R1 that meets this condition.
R1 = applied voltage – 1.4 V – 10 kΩ
500 µA
BEEP pin (pin 4)
· If the BEEP pin is used, use the smallest value of R102 (see figure)
possible (but note that this value must be under 100 Ω) to prevent
degradation of the IC's output noise voltage (VNO) characteristics.
Pin 21 IC Internal Equivalent Circuit
500 µA or less
About 1.4 V (2VBE)
Applied standby
voltage
Protection circuits
· The LA4906 includes an on-chip thermal protection circuit to prevent
destruction of or damage to the IC if abnormal heating occurs. If, due to
an inadequate heat sink or other reason, the IC junction temperature (Tj)
reaches or exceeds 160°C, the output is gradually attenuated by the
operation of the thermal protection circuit.
· The overvoltage protection circuit operates if the VCC voltage exceeds 20 V.
· While the LA4906 includes a power supply/ground short protection
circuit, it does not include a load shorting protection circuit. The idea
behind this design is that the thermal shutdown protection circuit will
protect the IC itself if the load is shorted. However, since a load short will
also cause temperature increases in the external transistor and coil, care is
required in handling this case.
Beep signal
Other notes
· Pin 22 is not connected electrically to any other points within the package.
No. 5714-6/10
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