Regulator ICs System power supply for car stereos BA3915B 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. Applications Car audio systems Features 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 voltage. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 226 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 BA3915B Block diagram 227 Regulator ICs Pin descriptions (Ta = 25C, BACKUP / ACC = 13.2V) 228 BA3915B Regulator ICs BA3915B Input / output circuits 229 Regulator ICs 230 BA3915B Regulator ICs BA3915B Electrical characteristics (unless otherwise noted, Ta = 25C, BACKUP / ACC = 13.2V) 231 Regulator ICs 232 BA3915B Regulator ICs BA3915B Measurement circuits 233 Regulator ICs 234 BA3915B Regulator ICs BA3915B 235 Regulator ICs Input / output timing chart 236 BA3915B Regulator ICs BA3915B MUTE timing chart 237 Regulator ICs AM / FM output timing chart 238 BA3915B Regulator ICs BA3915B 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 239 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. BA3915B 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 range. (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 conditions. (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 240 (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 BA3915B Electrical characteristic curves External dimensions (Units: mm) 241