346

Optical disc ICs

BA6398FP

FOperation notes

(1)

The BA6398FP has an internal thermal shutdown

circuit. Output current is muted when the chip tempera-

ture 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)

The driver circuit shuts down when the supply volt-

age drops below 4.5V (typically), and starts up again

when the voltage rises above 4.7V (typically).

(5)

Muting occurs during thermal shutdown, mute-on

operations or a drop in the bias pin voltage or supply volt-

age. In each case, only the drivers are muted. During

muting, the output pins remain at the internal bias volt-

(6)

The internal input resistor has a positive tempera-

ture 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.

(7)

Be sure to connect the IC to a 0.1

µF bypass capaci-

tor to the power supply, at the base of the IC.

(8)

The radiating fin is connected to the package’s in-

ternal GND, but should also be connected to an external

ground.

(9)

The capacitor between regulator output (pin 6) and

GND also serves to prevent oscillation of the IC, so select

one with good temperature characteristics.

FElectrical characteristic curves