Optical disc ICs 2-channel reversible-motor driver BA6191 The BA6191 is a 2-channel motor driver for CD player changers and electric volume switches, among other applications. Because it uses a negative power supply, this IC uses the power supply of application products efficiently. Applications CD player, etc. Features 1) Two-channel reversible-motor driver. 2) Four modes - forward, reverse, stop (free rotation) and brake are output according to control logic input (two inputs). 3) Output voltage is set with the Vref pin. Absolute maximum ratings (Ta = 25C) Recommended operating conditions (Ta = 25C) 154 4) Internal power supply voltage drop mute circuit. 5) Internal thermal shutdown circuit. 6) Negative power supply. Optical disc ICs BA6191 Block diagram Pin descriptions 155 Optical disc ICs Input / output circuits 156 BA6191 Optical disc ICs BA6191 Electrical characteristics (unless otherwise noted, Ta=25C, VCC=10V, Vref=2.5V) Circuit operation (1) Forward / reverse control block The IC outputs the forward, reverse, stop (free rotation) or brake mode in accordance with the two control logic inputs. 〈Forward and reverse modes〉 An output voltage twice that of the reference voltage is generated. 1) Normal voltage is not output when the reference voltage is below 1.0V or about VCC / 2–1.0V. 2) VCC is the reference voltage for the input voltage of logic input pins. In terms of potential relative to VEE, the HIGH level are (VCC+5.0)V and LOW level are (VCC.)V. 3) Fig. 2 shows each pin’s potential level. 〈Stop mode〉 Each pin changes to the high impedance state. 〈Brake mode〉 Each pin outputs 0V. Logic input and output truth table 157 Optical disc ICs Circuit operation (2) Thermal shutdown The BA6191 has an internal shutdown circuit with hysteresis capabilities. Output current is muted when the chip temperature exceeds 175C (typically) and restored when the chip temperature falls to 150C (typically). Application example Operation notes (1) Attach a bypass capacitor (roughly 0.1µF) to the power supply, at the base of the IC. (2) The radiating fin is internally grounded to the package and so should be connected to an external ground. 158 BA6191 (3) Power supply voltage drop muting The output current is muted when the power supply voltage (VCC) drops below 3.0V. During muting, the output voltage is VEE. Optical disc ICs BA6191 Thermal derating curve Electrical characteristic curves External dimensions (Units: mm) 159