318
Optical disc ICs
4-channel BTL driver for CD players
BA6297AFP
The BA6297AFP is a 4-channel BTL driver for CD player actuators and motors. The preamplifier has both positive and
negative input pins and output pins, making this IC suited to a broad range of applications.
F
Applications
CD players
F
Features
1) 4-channel BTL driver.
2) HSOP 28-pin package allows for miniaturization of
applications.
3) Internal thermal shutdown.
4) Driver gain is adjustable with a single attached resis-
tor.
5) Both positive and negative input pins, for adaptability
for a wide range of inputs (including negative phase
input).
F
Absolute maximum ratings (Ta = 25
_
C)
F
Recommended operating conditions (Ta = 25
_
C)
V
CC
*
V
F
2
322
Optical disc ICs
BA6297AFP
F
Circuit operation
The BA6297AFP comprises a 4-channel driver, internal
bias amplifier, mute pin and thermal shutdown.
(1)
Driver
The driver uses a buffer to output one of the outputs from
its preamplifier with no modification, and uses an inver-
sion amplifier to invert the other output before sending it
to the driver buffer. The inversion amplifier's reference is
the bias voltage generated internally (pin 7 voltage), and
so the preamplifier output must make the zero level equal
to the internal bias voltage. See Figs. 7 and 8 for exam-
ples.
(2)
Internal bias amplifier
Configured as shown in Fig. 9. The internal bias voltage
(V
ref
) is calculated thus :
V
ref
=
(3)
Mute pin (pin 15)
The output current is muted when this pin receives the
low level or a high impedance. Set the pin voltage at high
during normal operation.
(4)
Thermal shutdown
The BA6297AFP has an internal thermal shutdown cir-
cuit. Output current is muted when the chip temperature
exceeds 175
_
C (typically).
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