Rohm BA6297AFP 4-channel btl driver for cd player Datasheet

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.
Applications
CD players
Features
1) 4-channel BTL driver.
2) HSOP 28-pin package allows for miniaturization of
applications.
3) Internal thermal shutdown.
Absolute maximum ratings (Ta = 25C)
Recommended operating conditions (Ta = 25C)
318
4) Driver gain is adjustable with a single attached resistor.
5) Both positive and negative input pins, for adaptability
for a wide range of inputs (including negative phase
input).
Optical disc ICs
BA6297AFP
Block diagram
Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 8V, f = 1kHz, RL = 8Ω)
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Electrical characteristic curves
320
BA6297AFP
Optical disc ICs
BA6297AFP
Measurement circuit
321
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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 inversion 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 examples.
BA6297AFP
(2) Internal bias amplifier
Configured as shown in Fig. 9. The internal bias voltage
(Vref) is calculated thus :
Vref=
VCCVF
2
(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 circuit. Output current is muted when the chip temperature
exceeds 175C (typically).
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Operation notes
(1) The BA6297AFP has an internal thermal shutdown
circuit. Output current is muted when the chip temperature exceeds 175C (typically).
(2) If the mute pin (pin 15) voltage is opened or lowered
below 0.5V, the output current will be muted. Pin 2 should
be pulled up above 2.0V during normal use. During muting, the output pins remain at the internal bias voltage,
roughly (VCCVF) / 2.
BA6297AFP
(3) Be sure to connect the IC to a 0.1µF bypass capacitor to the power supply, at the base of the IC.
(4) The radiating fin is connected to the packages internal GND, but should also be connected to an external
ground.
Application example
External dimensions (Units: mm)
323
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