BA6798S

Optical disc ICs 4-channel BTL driver for CD players BA6798S The BA6798S is a 4-channel H-bridge BTL driver for CD players and actuators. The 5V regulator and internal standard operational amplifier make this IC suited to a broad range of applications. FApplications CD players and CD-ROM drives FFeatures 1) 4-channel BTL driver. 2) SDIP M 24-pin package for high package power. 3) Internal thermal shutdown circuit. 4) Driver gain is adjustable with a single attached resistor. 5) Internal 5V regulator. (requires attached PNP transistor) FAbsolute maximum ratings (Ta = 25_C) 374 Optical disc ICs FBlock diagram BA6798S FPin descriptions 375 Optical disc ICs FPin equivalent circuit diagrams BA6798S FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 8V, f = 1kHz, RL = 8Ω) 376 Optical disc ICs FMeasurement circuit BA6798S 377 Optical disc ICs FCircuit operation (1) Driver Inputs to the IC are the focus tracking error signal from the servo preamplifier and the control signal from the motor. BA6798S The input signals, which normally center on 2.5V, are V / I converted by the preamplifier, generating a current corresponding to the input voltage. This current is passed through a resistor and into the internal reference voltage component, the preamplifier output being a signal centering on the internal reference voltage. Both positive and negative phases are created during V / I conversion, generating BTL output via the driver buffer. (2) Regulator T...