ROHM BA5972

Optical disc ICs
BTL driver for CD-ROMs
BA5972FP
The BA5972FP is a 4-channel BTL driver developed for use with CD-ROMs. A multi-purpose operational amplifier is
equipped in each channel to allow use in a variety of applications. Also, by applying independent power supplies for both
the pre-stage and power-stage, with the power-stage power supply further split into two so one power supply handles
two channels each, a highly efficient driver has been realized.
FApplications
CD-ROM, DVD-ROM, MD, and optical discs
FFeatures
1) Wide dynamic range (VOUT = 4V [Typ.] when PreVCC
= 8V, PowVCC = 5V, and RL = 8Ω).
2) Internal thermal shutdown circuit.
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
662
3) Internal mute functions.
4) Internal standby functions.
Optical disc ICs
BA5972FP
Block diagram
Pin descriptions
663
Optical disc ICs
Input / output circuits
664
BA5972FP
Optical disc ICs
BA5972FP
FElectrical characteristics (unless otherwise noted, Ta = 25_C, PreVCC = 8V, PowVCC1 = 5V, PowVCC2 = 8V, BIAS = 2.5V,
FElectrical characteristics (RL = 8Ω)
665
Optical disc ICs
Measurement circuit
666
BA5972FP
Optical disc ICs
BA5972FP
Measurement circuit switch table
(1) Circuit current and standby (VMT = 0V, VIN = 2.5V, RL ! OFF, OPB ! 1, NF ! 1, OPRL ! 1)
(2)
Driver block (VST = 5V, RL ! ON, OPB ! 1, NF ! 1, OPRL ! 1)
(3)
Pre-stage operational amplifier block (VST = 5V, VMT = 0V, RL ! OFF)
667
Optical disc ICs
Application example
668
BA5972FP
Optical disc ICs
FOperation notes
(1) The BA5972FP contains a thermal shutdown circuit.
When the chip temperature reaches 175_C (Typ.), the
output current is muted. If the chip temperature then
drops below 150_C (Typ.), then the mute is released.
(2) By having the mute pin (pin 7) voltage pulled up to
2.0V or greater, you can mute the output current for channels 1 and 4. For normal conditions, have pin 7 open or
at 0.5V or below.
(3) If the voltage of the bias pin (pin 1) drops below 1.4V
(Typ.), outputs are muted.
For normal conditions, have the voltage above 1.7V.
(4) If the power supply voltage drops below 3.8V (Typ.),
internal circuits turn off. If the power supply voltage then
rises to 4.0V (Typ.), the circuits turn on.
(5) If the voltage of the thermal shutdown, mute ON, or
bias pin drops, or if the power supply voltage drops, the
mute is activated; however, in these situations, only the
drivers are muted.
Also, the output pin voltage becomes the internal bias
voltage (approx. VCC / 2).
BA5972FP
(6) If the standby pin voltage is open or 0.5V or below,
the circuit current enters the standby condition.
For normal operation, have the standby pin voltage
pulled up to 2.0V or greater.
(7) Connect a bypass capacitor (approx. 0.1µF) between the bases of the power supply pins of this IC.
(8) Even though the radiation fins are connected to
ground within the package, be sure to also connect them
to a ground externally as well.
(9) The application example will assure excellent results, but nevertheless, be sure to carefully check all
characteristics during use. During use with constants in
the external circuitry modified, be sure to leave a sufficient margin in order to take into consideration fluctuations in the static and transient characteristics of the external components and this IC.
Also, be aware that ROHM has not sufficiently performed
all confirmations regarding patent rights.
FElectrical characteristic curves
669
Optical disc ICs
External dimensions (Units: mm)
670
BA5972FP