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Optical disc ICs

4-channel BTL driver for CD players
BA5937AFP
The BA5937AFP is a 4-channel BTL driver developed for use with CD players. In addition to internal drivers for the focus coil, tracking coil, and sled motor, it also contains a driver for the loading motor. FApplications CD-ROM, CD players FFeatures 1) Perfect for compact applications with the use of the HSOP 28-pin power package. 2) Internal thermal shutdown circuit. 3) Gain is adjustable with externally connected resistor. (For channels 1, 3, and 4.) FAbsolute maximum ratings (Ta = 25_C)

4) External mute pin enables the muting of the output current for channels 1 and 4. 5) Power supply is divided into three systems (VCC1 = ch1 and ch4, VCC2 = ch2 and current source, VCC3 = ch3).

FRecommended operating conditions (Ta = 25_C)

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FBlock diagram

BA5937AFP

FPin descriptions

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FInput / output circuits

BA5937AFP

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FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 8V, RL = 8, VBIAS = 2.5V)

BA5937AFP

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FMeasurement circuit

BA5937AFP

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FApplication example

BA5937AFP

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FOperation notes (1) Output mode switch for loading motor driver (VCC = 8V)

BA5937AFP

Note: Loading driver gain is 0dB.

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(2) Voltage setting for loading motor driver (ex: forward mode)

BA5937AFP

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.

(3) The BA5937AFP contains a thermal shutdown circuit. When the chip temperature reaches 175_C (Typ.), the output current is muted. If the chip temperature then drops below 150_C (Typ.), then the mute is released. (4) If the voltage of the bias pin (pin 23) drops below 1.0V (Typ.), outputs are muted. For normal conditions, have the voltage above 1.4V and below 6.5V. (5) 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.

(6) If the voltage of the thermal shutdown, mute ON, 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. (VCC*VF) / 2). (7) Connect a bypass capacitor (approx. 0.1µF) between the bases of the power supply pins of this IC. (8) Even though the radiation fins are connected to ground within the package, be sure to also connect them to a ground externally as well.

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FElectrical characteristic curves

BA5937AFP

FExternal dimensions (Units: mm)

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