GP509

Features:

• low amplifier current (typical 105 A)
• low noise and distortion
• 1.0 to 5 VDC operating range
• independent preamplifier
• Class A output stage
• variable transducer current
• 4.0 k microphone decoupling resistor, on-chip


Pinout




Specifications

PARAMETER	VALUE / UNITS
Supply Voltage Power Dissipation Operating Temperature Storage Temperature	5V DC 25 mW -10o to + 40oC -20o to + 70oC

Description

The GP509 is a Class A amplifier utilizing Gennum's proprietary low voltage JFET technology. GP509 consists of a singleended, low noise inverting gain block, a Class A output stage, and an on-chip microphone decoupling resistor.

Block A typically has an open loop voltage gain of 56 dB, with the closed loop gain set by the ratio of the feedback resistor to the source impedance. GP509 is recommended that the maximum closed loop gain be 20 dB lower than the open loop gain. All blocks of the device are internally bias compensated, preventing any DC current flow via external feedback resistors. Without this compensation, audible scratchiness would be present during changes in volume control settings.

The output stage of the GP509 is a Class A current drive. It has a fixed reference voltage of typically 30 mV at pin 7 of the device. The current that flows in the transducer is the ratio of the 30 mV reference voltage and the on-chip emitter resistor (RE). To increase the bias current in the transducer, simply place an external RE resistor from pin 7 to ground, thereby decreasing the equivalent emitter resistance and increasing the current.