BA3911 ROHM | Alldatasheet

Document overview

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Technical content

Features

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 sys- tems are built in. 2) All output circuits use a PNP transistor with a low sat- uration voltage. 3) Output current limit circuit prevents damage to the IC in the event output is short-circuited. 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. Block diagram

Absolute maximum ratings (Ta = 25/C0095C) Recommended operating conditions (Ta = 25/C0095C) Pin descriptions

Electrical characteristics (unless otherwise noted, Ta = 25/C0095C and VCC = 13.2V)

Estimate of allowable power dissipation Except under transitional conditions, the power dissipation of this IC is 3W per unit at 25/C0095C. 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 /C0083Power consumed by VDD 5.6V P 1 = (A 5.6V) I1 (I1 /20 I1 /10) A /C0083Power consumed by COM 8.7V P 2 = (A 8.7V) I2 (I2 /30 I2 /10) A /C0083Power consumed by AMP P 3 = 0.5V I3 (I3 /100 I3 /10) A /C0083Power consumed by ANT P 4 = 0.5V I4 (I4 /100 I4 /10) A /C0083Power consumed by AM 8.7V P 5 = (A 8.7V) I5 (I5 /30 I5 /10) A /C0083Power consumed by FM 8.7V P 6 = (A 8.7V) I6 (I6 /50 I6 /10) A /C0083Power consumed internally by each circuit P7 = VCC supply current (about 5mA) PMAX. = P1 P2 P3 P4 (P5 or P6, whichever is larger) P7 Fig.1

Fig.2

Fig.3

(1) Example of application The application circuit of Fig. 3 is recommended for use. Make sure to confirm the adequacy of parts characteris- tics. When using the circuit with changes to external cir- cuit constants, make sure to leave sufficient margins in consideration of fluctuations in the IC and external com- ponents including static and transitional characteristics. Note that ROHM has not carried out extensive survey re- garding 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, char- acteristic 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 maxi- mum power within the operating temperature range. (4) Overvoltage protection circuit The overvoltage protection circuit turns OFF each output when the potential difference between V CC (pin 7) and GND (pin 12) is more than about 26V at normal tempera- ture. 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 ca- pacitor having a capacitance of 10µF or greater between GND and each of the V DD (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 V DD (pin 5), AMP (pin 6), ANT (pin 8), COM (pin 9), AM (pin 10), and FM (pin 11) outputs, based on the re- spective 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 out- put voltage is less than 1V F (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 con- trolled, 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 physi- cal safety measures such as fusing if special mode is ex- pected. (10) We recommend installing a bypass line in particular applications if there is a mode where potential difference between each output and input (V CC ) or GND is reversed from the normal state.

External dimensions (Units: mm) 225 Regulator ICs BA3911 Electrical characteristic curves