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 mo-
tor.
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 sig-
nal centering on the internal reference voltage. Both pos-
itive and negative phases are created during V / I conver-
sion, generating BTL output via the driver buffer.
(2) Regulator
This is a typical series regulator that generates a refer-
ence voltage internally. A PNP low saturation transistor
must be connected.
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