TZA1024

The TZA1024 is a data amplifier and laser supply circuit for voltage output mechanisms found in a wide range of audio and video CD systems. The device contains an RF amplifier and an automatic laser power control circuit.

The TZA1024 preamplifier forms a versatile, programmable interface for voltage output CD mechanisms to the Philips' digital signal processor CD10 (SAA7324).The RF bandwidth allows this device to be used in CD-A/V and CD-R/W applications with a data rate up to a maximum of n = 4 times speed. The RF gain can be adapted for CD-A/V discs or CD-R/W discs by means of the gain select signal.

The equalizer can be adjusted for n = 1 or n = 2 times speed with the equalizer/speed select signal. For n = 4 times speed the RF is not equalized.The TZA1024 can be adapted to a wide range of voltage output mechanisms by means of external resistors.
The ALPC circuit will maintain control over the laser diode current. With an on-chip reference voltage generator, a constant and stabilized output power is ensured independent of ageing. The ALPC can accommodate N- or P-substrate monitor diodes.

A separate supply voltage connection for the laser allows the internal power dissipation to be reduced by connecting a low voltage supply. The laser output current range of TZA1024 can be optimized to fit the requirements of the laser diode by means of one external resistor. When a DC-to-DC converter is used, in combination with the control loop of the ALPC, the adjustable output current range provides the possibility to compensate for the extra gain a DC-to-DC converter introduces in the control loop.