Sony WM-FX193 LB8115 Audio Chip

The Sony WM-FX193 has the LB8115 audio IC, which many considered as a pinnacle of audio chip development. This IC is the main controller managing the logic functions, and it has built-in amplifiers, and the driver circuitry for the motor. This would have been the next step forward in the evolution of a single chip cassette Walkman. However, from around 2000 people began to realise the benefits of MP3 audio and cassette players started to lose the top position.

Comparing this unit with the 1990s Walkmans, this design is simpler with fewer ICs and discrete conventional components. As you can see the SMD, count is quite high though.

LB8115

The interesting thing to note about this chip is that the preamplifier, Mega Bass, headphone power amp, and motor driver circuits are all incorporated into this one block. Pins 39, 40, and 41 drive the three phase motor coils. Even though it is driving inductive coils it is virtually silent, which is remarkable!

This is why I just love Sony Walkmans.

Motor Driver

This block diagram shows the motor driver operation logic. Pins 39, 40, 41 are for driving the motor directly. A logic signal on pin 43 determines forward or reverse drive of the motor. The driver coils receive controlled pulses to minimize the power usage, as this IC also has to manage the power to the subsystems.

Amplifiers

Although the WM-FX193 does not have auto reverse, this chip was for players with an auto reverse function because it has preamplifier inputs at pins 12, 11, 10, and 9 for all four tracks of the tape.

The IC usually performs automatic switching to select the tracks. In this model, the switches connect permanently to side A of the tape, since the user will have to turn over the tape manually.

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