Datasheet BA6397FP Datasheet (ROHM)

Optical disc ICs

4-channel BTL driver for CD players

BA6397FP

The BA6397FP is a 4-channel BTL driver for CD player motors and actuators. The 5V regulator and internal standard
operational amplifier make this IC suited to a broad range of applications.

Applications
CD players and CD-ROM drives

Features

1) HSOP 28-pin package allows for miniaturization of
applications.

2) Low number of external components.

3) Driver gain is adjustable with a single attached resis­tor.

Absolute maximum ratings (Ta = 25C)

4) Internal 5V regulator. (requires attached PNP tran­sistor)

5) Internal standard operational amplifier.

6) Internal thermal shutdown circuit.

Recommended operating conditions (Ta = 25C)

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Optical disc ICs BA6397FP

Block diagram

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Optical disc ICs BA6397FP

Pin descriptions

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Optical disc ICs BA6397FP

Input/output circuits

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Optical disc ICs BA6397FP

Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 8V, f = 1kHz, RL = 8Ω)

Circuit operation

(1) Driver
Inputs to the IC are the focus tracking error signal from
the servo preamplifier and the control signal from the mo­tor. The input signals, which normally center on 2.5V , are
V /I converted by the preamplifier, generating a current
corresponding to the input voltage. This current is

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passed through a resistor and into the internal reference
voltage component, the preamplifier output being a sig­nal centering on the internal reference voltage. Two sys­tems (positive phase and negative phase) are created
during V /I conversion, generating BTL output via the
driver buffer.

Optical disc ICs BA6397FP

(2) Regulator
This is a typical series regulator that generates a refer­ence voltage internally. A PNP low saturation type tran­sistor must be connected.

(3) Operational amplifier
A standard 4558 type.

Application example

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Optical disc ICs BA6397FP

Operation notes
(1) The BA6397FP has an internal thermal shutdown
circuit. Output current is muted when the chip tempera­ture exceeds 175C (typically).
(2) If the mute pin (pin 7) voltage is opened or lowered
below 0.5V , the output current will be muted. Pin 7 should
be pulled up above 2.0V during normal use.
(3) The bias pin (pin 23) is muted when lowered below

1.4V (typically). Make sure it stays above 1.6V during
normal use.
(4) Muting occurs during thermal shutdown, mute-on
operations or a drop in the bias pin voltage. In each case,
only the drivers are muted. During muting, the output pins
remain at the internal bias voltage, roughly (V

CC–VF)/2.

(5) The internal input resistor has a positive tempera­ture coefficient of roughly 2000ppm / degree, and so
when changing the gain using an attached resistor, gain
will also change at a rate of roughly 2000ppm / degree.
There is virtually no gain variation due to temperature
when using the internal input resistor.
(6) Be sure to connect the IC to a 0.1µF bypass capaci­tor to the power supply, at the base of the IC.
(7) The radiating fin is connected to the package’s in­ternal GND, but should also be connected to an external
ground.
(8) The capacitor between regulator output (pin 6) and
GND also serves to prevent oscillation of the IC, so select
one with good temperature characteristics.

Electrical characteristic curves

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Optical disc ICs BA6397FP

Electrical characteristic curves

External dimensions (Units: mm)

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