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Número de pieza | BA3924 | |
Descripción | Power supply for CD radio cassette players | |
Fabricantes | ROHM Semiconductor | |
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No Preview Available ! Regulator ICs
Power supply for CD radio cassette
players
BA3924
The BA3924 is a system reference power supply for use in CD radio cassette players. Outputs dedicated to a micropro-
cessor (5.0V), CD player (7.5V), audio system (7.5V), and motor drive (9V) are built in. Also built in is a VCC)B output
that allows turning ON and OFF the supply voltage by HIGH and LOW levels of the standby pin.
FApplications
CD radio cassette players
FFeatures
1) With outputs dedicated to a microcontroller, CD play-
er, audio system, and motor drive, the IC is best
suited for CD radio cassette players.
2) Zero standby current (typ.).
3) Output current limit circuit protects the IC against
short-circuiting damage.
FAbsolute maximum ratings (Ta = 25_C)
4) Compact 12-pin package allows large power dissipa-
tion.
5) Thermal shutdown circuit protects the IC against
thermal damage.
6) VCC)B output allows turning ON and OFF the power
supply voltage by HIGH and LOW levels of the stand-
by pin.
FRecommended operating conditions (Ta = 25_C)
141
1 page Regulator ICs
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 12V)
BA3924
145
5 Page Regulator ICs
BA3924
(3) Preventing oscillation at each output
To stop output oscillation, make sure to connect a capaci-
tor between GND and each of the MOTOR (pin 3), AU-
DIO (pin 5), COMMON (pin 6), and CD (pin 8) output
pins. Use capacitors whose valve are not below the val-
ues denoted in the application circuit (Fig. 4) and not sus-
ceptible to temperature.
(4) Ground pins
Pre GND (pin 10) and Pow GND (pin 12) are the ground
pins of the IC. Pin 10 is the reference ground pin for pow-
er supplies, including the built-in reference power supply,
and the comparators. Voltage and threshold values may
shift if the potential of pin 10 is unstable. Take sufficient
care when designing the conductor pattern near this pin.
The source current from this pin is in the level of a few mil-
liamperes. Pin 12, which is connected to the ground
traces other than those connected to pin 10, is connected
with the IC substrate and the back metal.
(5) External PNP transistors
ROHM’s 2SB1370 (E- or F-rank) is recommended. This
is a TO-220FP type transistor.
(6) Overvoltage protection circuit
Although the absolute maximum voltage is 22V, a peak
voltage of 30V for 200ms is assured only during the
standby state (pin 11 is LOW). The overvoltage circuit is
activated when the VCC voltage exceeds 23V. When the
circuit is activated, a standby circuit current (IST) of a few
milliamperes flows in the IC.
The overvoltage protection circuit is also activated if a
voltage exceeding the absolute maximum rating is ap-
plied while the STANDBY pin is HIGH. As a result all the
output voltage is turned off.
(7) Overcurrent protection circuit
If the output current of any of the MOTOR (pin 3), AUDIO
(pin 5), COMMON (pin 6), and CD (pin 8) exceeds the
current capacity, the built-in current limit circuit limits the
current to a set level. If the potential of each pin is about
the same as that of Pow GND (pin 12), the output current
is reduced to the level of the ground short-circuit current
given in the “Electrical Characteristics.”
(8) Thermal protection
The circuit current, the limit current of each power supply
output, and the ground short-circuit current decrease
gradually with increasing temperature. For further
protection, the thermal shutdown circuit turns off all out-
puts when the IC is overheated, and brings back to nor-
mal operation when the temperature is decreased to a
certain level.
151
11 Page |
Páginas | Total 12 Páginas | |
PDF Descargar | [ Datasheet BA3924.PDF ] |
Número de pieza | Descripción | Fabricantes |
BA3924 | Power supply for CD radio cassette players | ROHM Semiconductor |
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