BA3950

Regulator ICs System power supply for CD playerequipped audio systems BA3950A With 13.3V (external transistor required), 12V, 10V, and 5.6V outputs, the BA3950A power supply IC is best suited for CD player-equipped audio systems. FApplications CD player-equipped audio systems FFeatures 1) 13.3V (external transistor required), 12V, 10V, and 5.6V outputs are built in (one output for each voltage). 2) Output current limit circuit protects the IC against short-circuiting damage. 3) Thermal protection circuit prevents heat damage to the IC. 4) Compact SIP-M12 package allows a large power dissipation. FAbsolute maximum ratings (Ta = 25_C) FRecommended operating conditions (Ta = 25_C) 199 Regulator ICs FBlock diagram BA3950A FPin descriptions 200 Regulator ICs FInput / output circuits BA3950A 201 Regulator ICs FElectrical characteristics (unless otherwise noted, Ta = 25_C and VCC = 8V) BA3950A 202 Regulator ICs FCircuit operation The MAIN, MOTOR, and µ-COM outputs rise when ST is 1.4V (Typ.). The CDP output rises when MODE is 1.4V (Typ.) and ST is 1.4V (Typ.). BA3950A 203 Regulator ICs FApplication example BA3950A FOperation notes (1) 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. (2) Power dissipation (Pd) Refer to the heat reduction characteristics (Fig. 4) and the rough estimation of IC power dissipation given on a separate page. If power dissipation exceeds the allowable limit, the functionality of IC will be degraded (such as reduction of current capacity by increased chip temperature). Make sure to use the IC within the allowable range of power dissipation with a sufficient margin. (3) Preventing oscillation at each output To stop oscillation of output, make sure to connect a capacitor having a valve 1µF or greater between GND and each output pin. Also, be sure to connect a bypass capacitor between VCC and GND for further stabilization of output. (To avoid the noise effect, layout the grounding close to the IC.) Oscillation can occur if capacitance is susceptible to temperature. We recommend using a tantalum electrolytic capacitor with minimal changes in capacitance. 204 Regulator ICs (4) Overcurrent protection circuit An overcurrent protection circuit is installed in each output system, 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. Note that these protection circuits are only good for preventing damage from sudden accidents. Make sure your design does not cause the protection circuit to operate continuously under transitional conditions (for instance, when output is clamped at 1VF or higher). Note that the circuit ability is negatively correlated with temperature. FThermal derating curve BA3950A (5) Thermal protection circuit A built-in thermal protection circuit prevents thermal damage to the IC. All outputs are switched OFF when the circuit operates, and revert to the original state when temperature drops to a certain level. (6) Improving ripple rejection by capacitors Ripple rejection of the CDP and MAIN outputs can be improved by installing a capacitor that reduces the AC gain. (7) Malfunction in intense electric fields Note that bringing the IC into an intense electric field (such as a radio relay station) may result in malfunction. Estimate of allowable power dissipation (PMAX.) S Power consumed by CDP S Power consumed by µ-COM S Power consumed by MAIN S Power consumed internally by each circuit P1 = (VCC * CDP) maximum load current of CDP maximum load current of µ-COM P2 = {VCC * (µ-COM)} maximum load current of MAIN P3 = (VCC * MAIN) supply current P4 = VCC PMAX. = P1 ) P2 ) P3 ) P4 205 Regulator ICs FExternal dimensions (Units: mm) BA3950A 206