BA6295

Optical disc ICs 2-channel BTL driver for CD players BA6295AFP The BA6295AFP is a 2-channel BTL driver for CD player actuators and motors. This IC delivers a large output current and is ideal for car CD players. FApplications CD players FFeatures 1) 2-channel BTL driver. 2) High output current. (Io = IA Typ.) 3) HSOP 28-pin package allows for miniaturization of applications. FAbsolute maximum ratings (Ta = 25_C) 4) Internal thermal shutdown. 5) Gain is adjustable by inserting a resistor between pins 27 and 28 ; pins 18 and 16. FRecommended operating conditions (Ta = 25_C) 197 Optical disc ICs FBlock diagram BA6295AFP FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 10V, f = 1kHz) 198 Optical disc ICs FElectrical characteristic curves BA6295AFP FMeasurement circuit 199 Optical disc ICs FCircuit operation The BA6295AFP comprises a 2-channel driver, internal bias amplifier, mute pin, and thermal shutdown circuit. (1) Driver The input resistance of the driver is the focus tracking error signal from the servo preamplifier and the control signal from the motor. The input signals normally center on 2.5V, and are converted to a VCC / 2-centered signal by the internal level shift amplifier. BA6295AFP Both positive and negative phases are created during final V / I conversion, generating BTL output via the driver buffer. Because the gain adjustment pins (pins 15, 16, 27 and 28) are external, gain can be adjusted by connecting a resistor in parallel. (2) Internal bias amplifier This IC’s internal bias is 1 / 2 VCC. Ripple rejection can be increased and crosstalk reduced by connecting a capacitor to pin 23. (3) Mute pins The output current can be muted by switching one of these pins to the HIGH level. These pins are also used for thermal shutdown and should always remain at high impedance during normal operations. This is because the thermal shutdown feature is disabled when these pins are at the LOW level. FOperation notes (1) The BA6295AFP has an internal thermal shutdown circuit. Output current is muted when the chip temperature exceeds 190_C (typically). (2) Output current can but muted by raising the voltage between pins 22 and 8 above 1.5V. (3) Shorting pins 22 and 8 disables the thermal shutdown feature. (4) Be sure to connect the IC to a 0.1µF bypass capacitor to the power supply, at the base of the IC. (5) The radiating fin is connected to the package’s internal GND (pin 8), but both it and pin 8 should also be connected to an external ground. 200 Optical disc ICs FApplication example BA6295AFP FExternal dimensions (Units: mm) 201