Regulator ICs
System power supply for car stereos
The BA3915B is an one-chip power supply IC for use in car audio systems. The IC has seven output systems : one 5V
output (VDD), four 8.5V outputs (COM, FM, AM, AR), and two high-side switch outputs (ANT, AMP). The 5V outputs operate all the time if only the BCAD input is provided. The other outputs operate with BACKUP and ACC inputs, and their
ON / OFF is controlled by the STANDBY and MODE inputs.
Car audio systems
1) ACC and BACKUP voltages are monitored,
compared with the internally set values; one-shot
pulses are output to MUTE, which synchronizes with
the rising and falling of the STANDBY input.
2) ACC voltage is monitored, compared with the internally set value, and the result is output to ACCB.
3) All outputs use a PNP transistor with low saturation
Absolute maximum ratings (Ta = 25C)
Recommended operating conditions (Ta = 25C)
4) Output current limit circuit prevents damage to the IC
due to short-circuiting.
5) Overvoltage protection circuit provides protection
against surges from the ACC or BACKUP input.
6) Compact 16-pin POWER package allows large power dissipation.
Regulator ICs
Block diagram
Regulator ICs
Pin descriptions (Ta = 25C, BACKUP / ACC = 13.2V)
Regulator ICs
Input / output circuits
Regulator ICs
Regulator ICs
Electrical characteristics (unless otherwise noted, Ta = 25C, BACKUP / ACC = 13.2V)
Regulator ICs
Regulator ICs
Measurement circuits
Regulator ICs
Regulator ICs
Regulator ICs
Input / output timing chart
Regulator ICs
MUTE timing chart
Regulator ICs
AM / FM output timing chart
Regulator ICs
FEstimate of allowable power dissipation
Except under transitional conditions, the power dissipation of this IC is 3.4W per unit at 25_C. See Fig. 4 for heat reduction characteristics, including some cases where heat sinks are used.
A = maximum BACKUP voltage
B = maximum BCAP voltage
I1 = maximum output current for VDD (80mA)
I2 = maximum output current for COM (300mA)
I3 = maximum output current for FM (300mA)
I4 = maximum output current for AM (200mA)
I5 = maximum output current for AR (200mA)
I6 = maximum output current for ANT (250mA)
I7 = maximum output current for AMP (100mA)
S Power consumed by VDD 5.0V
S Power consumed by COM 8.5V
S Power consumed by FM 8.5V
S Power consumed by AM 8.5V
S Power consumed by AR 8.5V
S Power consumed by ANT
S Power consumed by AMP
S Power consumed internally by each circuit
P1 = (B 5.0V) I1 (I1 / 16 I1 / 10) B
P2 = (A 8.5V) I2 (I2 / 60 I2 / 10) A
P3 = (A 8.5V) I3 (I3 / 60 I3 / 10) A
P4 = (A 8.5V) I4 (I4 / 40 I4 / 10) A
P5 = (A 8.5V) I5 (I5 / 40 I5 / 10) A
P6 = (0.6V) I6 (I6 / 50 I6 / 10) A
P7 = (0.6V) I7 (I7 / 50 I7 / 10) A
P8 = A circuit current (about 10mA)
PMAX = P1 P2 (P3 or P4, whichever is larger) P5 P6 P7 P8
Regulator ICs
Operation notes
(1) Although the quality of this IC is rigorously controlled, the IC may be destroyed when the supply voltage
or the operating temperature exceeds their absolute
maximum ratings. Because short mode or open mode
cannot be specified when the IC is destroyed, be sure to
take physical safety measures, such as fusing, if any of
the absolute maximum ratings might be exceeded.
(2) Operating power supply voltage
When operating within the proper ranges of power supply
voltage and ambient temperature, most circuit functions
are guaranteed. Although the rated values of electrical
characteristics cannot be absolutely guaranteed, characteristic values do not change drastically within the
proper ranges.
a large capacitor. The circuit should be carefully set because output current is further restricted when output
voltage is less than 1VF (considered as short mode).
(7) Thermal protection circuit
A built-in thermal protection circuit prevents thermal
damage to the IC. All outputs except VDD are switched
OFF when the circuit operates, and revert to the original
state when the temperature drops to a certain level.
(8) BACKUP-ACC potential difference
If the BACKUP voltage exceeds the ACC voltage, a current flows through a protection diode connected internally between BACKUP and ACC. If the potential difference
is more than 1VF, this diode is fully turned on.
(3) Power dissipation (Pd)
Refer to the power dissipation characteristics (Fig. 4) and
the rough estimation of IC power dissipation given on a
separate page. Make sure your design allows the maximum required power within the operating temperature
(9) BCAP pin external diode
Voltage is supplied to BCAP from BACKUP through an
external diode. The maximum current consumption is
about 100mA. A reverse bias will be applied to the diode
if the BACKUP pin becomes 0V. Select a diode that has
sufficient electrical characteristics to cope with the above
(4) Overvoltage protection circuit
The overvoltage protection circuit turns OFF all outputs
when the potential difference between BACKUP (pin 14),
BCAP (pin 13), or ACC (pin 12) and GND (pin 16) is more
than about 26V at normal temperature. Make sure to use
the IC within this voltage limit.
(10) Grounding
Each ground trace must be adequately short from GND
(pin 16). Make sure to arrange the ground traces in a pattern that prevents mutual interference.
(5) Preventing oscillation at each output
To stop output oscillation, make sure to connect a capacitor having a capacitance of 10µF or greater between
GND and each of the ANT (pin 1), AMP (pin 2), VDD (pin
3), AM (pin 10), FM (pin 11), and COM (pin 15) output
pins. We recommend using a tantalum electrolytic capacitor whose capacitance is unsusceptible to temperature.
(6) Overcurrent protection circuit
An overcurrent protection circuit is installed on the ANT
(pin 1), AMP (pin 2), VDD (pin 3), AM (pin 10), FM (pin 11),
and COM (pin 15) outputs, based on the respective output current. This prevents IC destruction due to overcurrent, by limiting the current with a curve shape of “7” in the
voltage-current graph. The IC is designed with margins
so that current flow will be restricted and latching will be
prevented even if a large current suddenly flows through
(11) We recommend installing a bypass line in your application if there is a mode where potential difference between each output and input (VCC) or GND is reversed
from the normal state.
Regulator ICs
Electrical characteristic curves
External dimensions (Units: mm)