Optical disc ICs 4-channel BTL driver for CD players BA5934FP The BA5934FP is a 4-channel BTL driver developed to drive CD player motors and actuators. Perfect for compact applications with the use of the HSOP 28-pin power package. Applications CD players, CD-ROM Features 1) In addition to internal drivers for the focus coil, tracking coil, and sled motor, it also contains a driver for the loading motor. 2) Perfect for compact applications with the use of the HSOP 28-pin power package. 3) Requires few external components. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 718 4) Driver gain is adjustable with a single externally connected resistor. 5) Internal thermal shutdown circuit. 6) External mute pin enables the muting of the output current for channel 4. Optical disc ICs BA5934FP Block diagram Pin descriptions 719 Optical disc ICs Input / output circuits 720 BA5934FP Optical disc ICs BA5934FP Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 8V, RL = 8Ω, VBIAS = 2.5V) 721 Optical disc ICs Measurement circuit 722 BA5934FP Optical disc ICs Circuit operation (1) Driver block The input is the focus and tracking error signals from the servo pre-amplifier and the control signals for the motor system. The input signal is normally centered at 2.5V, and at the pre-amplifier, it undergoes V / I conversion to generate the current corresponding to the input voltage. This is then passed through a resistor and sent to the internal reference voltage block. BA5934FP This results in the output from the pre-amplifier being the signal at the center of the internal reference voltage. Furthermore, at the V / I conversion, forward and reverse phases are generated and the BTL output is then gained through the driver buffer. 723 Optical disc ICs (2) BA5934FP Output mode switch for loading motor driver (VCC = 8V) Note: Loading driver gain is 0dB. (3) Voltage setting for loading motor driver (ex: forward mode) ∗ When setting the output voltage from the loading driver, even if an output voltage is set that exceeds the maximum output voltage with respect to the power supply voltage, the output will not exceed the maximum output voltage. If a voltage is set that is under the maximum output voltage, the example above is applicable. Also, by having the loading input (pin 19) open, the maximum output voltage with respect to the power supply voltage is output. 724 Optical disc ICs BA5934FP Application example 725 Optical disc ICs Operation notes (1) The BA5934FP contains a thermal shutdown circuit. When the chip temperature reaches 175C (Typ.), the output current is muted. (3) If the voltage of the bias pin (pin 23) drops below 1.4V (Typ.), outputs are muted. For normal conditions, have the voltage above 1.6V and below 6.5V. (4) If the voltage of the thermal shutdown or bias pin drops, the mute is activated; however, in these situations, only the drivers are muted. Also, the output pin voltage becomes the internal bias voltage (approx. (VCCVF)/2). Electrical characteristic curves 726 BA5934FP (2) By having the mute pin (pin 7) voltage pulled up to 2.0V or greater, you can mute the output current for channels 1 and 4. For normal conditions, have pin 7 open or at 0.5V or below. The figure below is the timing chart for the high-impedance mute. (5) Connect a bypass capacitor (approx. 0.1µF) between the bases of the power supply pins of this IC. (6) Even though the radiation fins are connected to ground within the package, be sure to also connect them to a ground externally as well. Optical disc ICs BA5934FP External dimensions (Units: mm) 727