197
Optical disc ICs
2-channel BTL driver for CD players
BA6295AFP
The BA6295AFP is a 2-channel BTL driver for CD player actuators and motors. This IC delivers a large output current
and is ideal for car CD players.
F
Applications
CD players
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Features
1) 2-channel BTL driver.
2) High output current. (Io = IA Typ.)
3) HSOP 28-pin package allows for miniaturization of
applications.
4) Internal thermal shutdown.
5) Gain is adjustable by inserting a resistor between
pins 27 and 28 ; pins 18 and 16.
F
Absolute maximum ratings (Ta = 25
_
C)
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Recommended operating conditions (Ta = 25
_
C)
200
Optical disc ICs
BA6295AFP
F
Circuit operation
The BA6295AFP comprises a 2-channel driver, internal
bias amplifier, mute pin, and thermal shutdown circuit.
(1)
Driver
The input resistance of the driver is the focus tracking er-
ror signal from the servo preamplifier and the control sig-
nal from the motor. The input signals normally center on
2.5V, and are converted to a V
CC
/ 2-centered signal by
the internal level shift amplifier.
Both positive and negative phases are created during fi-
nal V / I conversion, generating BTL output via the driver
buffer. Because the gain adjustment pins (pins 15, 16, 27
and 28) are external, gain can be adjusted by connecting
a resistor in parallel.
(2)
Internal bias amplifier
This IC's internal bias is 1 / 2 V
CC
. Ripple rejection can be
increased and crosstalk reduced by connecting a capaci-
tor to pin 23.
(3)
Mute pins
The output current can be muted by switching one of
these pins to the HIGH level. These pins are also used
for thermal shutdown and should always remain at high
impedance during normal operations. This is because
the thermal shutdown feature is disabled when these
pins are at the LOW level.
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Operation notes
(1)
The BA6295AFP has an internal thermal shutdown
circuit. Output current is muted when the chip tempera-
ture exceeds 190
_
C (typically).
(2)
Output current can but muted by raising the voltage
between pins 22 and 8 above 1.5V.
(3)
Shorting pins 22 and 8 disables the thermal shut-
down feature.
(4)
Be sure to connect the IC to a 0.1
F bypass capaci-
tor to the power supply, at the base of the IC.
(5)
The radiating fin is connected to the package's in-
ternal GND (pin 8), but both it and pin 8 should also be
connected to an external ground.
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