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Regulator ICs
Reference voltage power supply
BA3911
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. FApplications Car audio systems FFeatures 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. FBlock 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.
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Regulator ICs
FAbsolute maximum ratings (Ta = 25_C)
BA3911
FRecommended operating conditions (Ta = 25_C)
FPin descriptions
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FInput / output circuits
BA3911
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FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 13.2V)
BA3911
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Regulator ICs
BA3911
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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.
BA3911
Fig.1 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) I2 ) (I2 / 30 ) I2 / 10) P2 = (A * 8.7V) I3 ) (I3 / 100 ) I3 / 10) A P3 = 0.5V I4 ) (I4 / 100 ) I4 / 10) A P4 = 0.5V I5 ) (I5 / 30 ) I5 / 10) P5 = (A * 8.7V) P6 = (A * 8.7V) I6 ) (I6 / 50 ) I6 / 10) supply current (about 5mA) P7 = VCC A A
A A
PMAX. = P1 ) P2 ) P3 ) P4 ) (P5 or P6, whichever is larger) ) P7
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FInput / output timing chart
BA3911
Fig.2
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FApplication example
BA3911
Fig.3
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FOperation 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 10F 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.
BA3911
(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.
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Regulator ICs
FElectrical characteristic curves
BA3911
FExternal dimensions (Units: mm)
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