GENERAL DESCRIPTION

The TDA1302T is a data amplifier and laser supply circuit for three-beam pick-up detectors applied in a wide range of mechanisms for Compact Disc and read only optical systems. The device contains 6 amplifiers which amplify and filter the focus and radial diode signals and provides an equalized RF signal suitable for single or double speed mode; the mode can be switched by means of the speed control pin. The device can accommodate astigmatic, single foucault and double foucault detectors and can be applied to all N-sub laser/monitor diode units even though the circuit has been optimized for the Philips CDM12 mechanisms and the digital servo controller TDA1301T. After a single initial adjustment the circuit will maintain control over the laser diode current thus resulting in a constant light output power which is independent of ageing. The IC is mounted in a small-outline package to enable it to be mounted close to the laser pick-up unit on the sledge.

FEATURES

• Six input buffer amplifiers with low-pass filtering and with virtually no offset

• HF data amplifier with a high or low gain mode

• Two built-in equalizers for single or double-speed mode ensuring high performance in both modes

• Fully automatic laser control including stabilization and an ON/OFF switch, plus a separate supply (VDDL) for power reduction

• Adjustable laser bandwidth and laser switch-on current slope

• Protection circuit to prevent laser damage due to supply voltage dip

• Optimized interconnectiion between pick-up detector and digital servo processor (TDA1301T)

• Wide supply voltage range

• Wide temperature range

• Low power consumption.