Regulator ICs
Reference voltage power supply
The BA3911 is a single-chip power supply IC for use in car audio systems. One 5.6V output for microcontrollers, three
8.7V outputs, and two outputs interlocked with BACKUP and ACC systems are built in.
Car audio systems
1) A power supply IC for car audio systems ; one 5.6V
output for microcontrollers, three 8.7V outputs, and
two outputs interlocked with BACKUP and ACC systems are built in.
2) All output circuits use a PNP transistor with a low saturation voltage.
3) Output current limit circuit prevents damage to the IC
in the event output is short-circuited.
Block diagram
4) Overvoltage protection circuit provides protection
against surges from the ACC or BACKUP inputs.
5) Compact 12-pin POWER package allows a large
power dissipation.
6) Thermal protection circuit prevents heat damage to
the IC.
Regulator ICs
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
FPin descriptions
Regulator ICs
Input / output circuits
Regulator ICs
FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 13.2V)
Regulator ICs
Regulator ICs
FEstimate of allowable power dissipation
Except under transitional conditions, the power dissipation of this IC is 3W per unit at 25_C.
See Fig.4 for thermal derating characteristics, including some cases where heat sinks are used.
A = maximum voltage for VCC
I1 = maximum output current for VDD
I2 = maximum output current for COM
I3 = maximum output current for AMP
I4 = maximum output current for ANT
I5 = maximum output current for AM
I6 = maximum output current for FM
S Power consumed by VDD 5.6V
S Power consumed by COM 8.7V
S Power consumed by AMP
S Power consumed by ANT
S Power consumed by AM 8.7V
S Power consumed by FM 8.7V
S Power consumed internally by each circuit
P1 = (A 5.6V) I1 (I1 / 20 I1 / 10) A
P2 = (A 8.7V) I2 (I2 / 30 I2 / 10) A
P3 = 0.5V I3 (I3 / 100 I3 / 10) A
P4 = 0.5V I4 (I4 / 100 I4 / 10) A
P5 = (A 8.7V) I5 (I5 / 30 I5 / 10) A
P6 = (A 8.7V) I6 (I6 / 50 I6 / 10) A
P7 = VCC supply current (about 5mA)
PMAX. = P1 P2 P3 P4 (P5 or P6, whichever is larger) P7
Regulator ICs
Input / output timing chart
Regulator ICs
Application example
Regulator ICs
Operation notes
(1) Example of application
The application circuit of Fig. 3 is recommended for use.
Make sure to confirm the adequacy of parts characteristics. When using the circuit with changes to external circuit constants, make sure to leave sufficient margins in
consideration of fluctuations in the IC and external components including static and transitional characteristics.
Note that ROHM has not carried out extensive survey regarding the patent right.
(2) Operating power supply voltage
When operating within 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.
(3) Power dissipation (Pd)
Refer to the heat reduction characteristics (Fig. 4) and
the rough estimation of IC power dissipation given on a
separate page. Make sure your design allows a maximum power within the operating temperature range.
(4) Overvoltage protection circuit
The overvoltage protection circuit turns OFF each output
when the potential difference between VCC (pin 7) and
GND (pin 12) is more than about 26V at normal temperature. Make sure to use the IC within this voltage limit.
(5) Preventing oscillation at each output
To stop oscillation of output, make sure to connect a capacitor having a capacitance of 10µF or greater between
GND and each of the VDD (pin 5), AMP (pin 6), ANT (pin
8), COM (pin 9), AM (pin 10), and FM (pin 11) 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 each of
the VDD (pin 5), AMP (pin 6), ANT (pin 8), COM (pin 9),
AM (pin 10), and FM (pin 11) outputs, based on the respective output current. This prevents IC destruction by
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 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 temperature drops to a certain level.
(8) Grounding
Each ground line in the application circuit of Fig. 3 must
be adequately short regarding the GND pin (pin 12).
Make sure to arrange the ground lines in a pattern that
prevents mutual interference.
(9) Although the quality of this IC is rigorously controlled, the IC may be destroyed when applied voltage or
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 special mode is expected.
(10) We recommend installing a bypass line in particular
applications 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)