SP8034A

® PRELIMINARY SP8034A 250 V/µs APC Amplifier with Integrated Photodiode and Gain Adjust Capability FEATURES ■ Slew Rate of 250V/us ■ 7ns Settling Time to 1% for 1.5V Step ■ 10 mV Output Offset Voltage ■ 20uV/°C Output Offset Drift ■ Digital Gain Select ■ +/- 6 dB External Gain Adjust VCC GAIN SEL RGCOM GND 1 2 3 4 SP8034A 8 Pin COB 8 7 6 5 VOUT VREF RGAIN2 RGAIN1 DESCRIPTION The SP8034A represents the next generation APC amplifier with integrated photodetector. This device monitors the light intensity of the laser diode in CD-R, CD-RW, DVD-R, DVD-RW and DVD-RAM assemblies by sensing the laser power with an integrated photodiode. The amplified signal from the APC contains the laser power information. This signal is subsequently fed back to the laser diode driver to control its power. The on-chip photodetector transforms incident light into a proportional current. This current is then converted to a voltage through a transimpedance amplifier. Adjustable gain is provided in the transimpedance amplifier by means of a gain control loop that is controlled by an external resistor. The external resistor is not part of the signal path, which greatly reduces the effects of all parasitic capacitances and inductances on the flex cable at these pins. The signal is buffered to provide reactive load drive capability. The SP8034A achieves an unparalleled level of performance by combining excellent DC stability and low noise with outstanding AC performance. This level of performance i...