GC509 GENNUM | Alldatasheet

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Technical content

GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. (905) 632-2996 fax: (905) 632-5946 Japan Branch: A-302, Mi yamae Villa ge, 2–10–42 Mi yamae, Suginami –ku, Tokyo 168, Japan tel. (03) 3334-7700 fax (03) 3247-8991 Class A Amplifier with

3 Independent Gain Blocks

Document No. 510 - 70 - 3

DESCRIPTION

The GC509 is a Class A amplifier utilizing Gennum’s proprietary low voltage JFET technology. It consists of two single- ended, low noise inverting gain blocks, a Class A output stage, and an on-chip microphone decoupling resistor. Blocks A and B typically have 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. It 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 GC509 is a Class A current drive. It has a fixed reference voltage of typically 55 mV at pin 8 of the device. The current that flows in the transducer is the ratio of the 55 mV reference voltage and the on-chip emitter resistor (R E). To increase the bias current in the transducer, simply place an external R E resistor from pin 8 to ground, thereby decreasing the equivalent emitter resistance and increasing the current. BLOCK DIAGRAM All resistors in ohms, all capacitors in Farads unless otherwise stated C OUT B IN R B OUT V E B GNDA OUT A IN VMIC C IN 2 10 9 21K

5 R MIC

  • A - B - C R E

FEATURES

  • 145 µA typical current drain
  • low noise and distortion
  • 1.0 to 5 VDC operating range
  • 2 independent preamplifiers
  • Class A output stage
  • variable transducer current
  • 4 kΩ microphone decoupling resistor STANDARD PACKAGING
  • 10 pin MICROpac
  • 10 pin PLID ®
  • 10 pin SLT
  • Chip (61 x 55 mils) Au Bump

R L = 1K R B = 4.7 2 10 9 21K R FA = 56.2K 2.7K - AC S 1.0 1.0 - B R FB = 47.5K R E = 47.5 VOUT

1.3 VDC

0.015 1.0 R S 3.3K VIN a b - C R E Fig.1 Test Circuit ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE / UNITS Supply Voltage 5V DC Power Dissipation 25 mW Operating Temperature -10 o to + 40oC Storage Temperature -20 o to + 70oC 101 CAUTION CLASS 1 ESD SENSITIVITY C OUT RE B OUT C IN VB GND B IN A IN VMIC A OUT PIN CONNECTION All resistors in ohms, all capacitors in Farads unless otherwise stated PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Amplifier Current IAMP 80 145 210 µA Transducer Current ITRANS RE= ∞ 200 275 350 µA Maximum Transducer Current ITRANS(MAX) RE= 0 Ω 2 - - mA Input Bias Current IBIAS RFA = 1M, RFB = 1M -50 0 50 nA Input Referred Noise IRN NFB 0.2 to 10kHz at 12dB/Oct - 1 2 µVRMS Harmonic Distortion THD S1 = b, V OUT = 500 mVRMS - 1 4 % Voltage Gain A V S1 = b, VOUT = 500 mVRMS 70 73 76 dB Stable with Battery Resistance Stability R B = 22 Ω - - 22 Ω Resistance (RB) to: Emitter Bias Voltage (Pin 8) V RE - 55 - mV Microphone Resistance R MIC 3 4 5 k Ω On Chip Emitter Resistor R E - 200 - Ω Preamp Current Drive Capability IOUT - 30 - µA All switches remain as shown in Test Circuit unless otherwise stated in CONDITIONScolumn.

ELECTRICAL CHARACTERISTICS

Conditions: Frequency = 1 kHz, Temperature = 25oC, Supply Voltage = 1.3 VDC

Fig. 3 Typical Hearing Aid Circuit RVC Gain of stage B = 20 Log 5.6K RGT Gain of stage A = 20 Log RS RLAC//21K Gain of stage C = 20 Log RE/120 10 10 10 Fig. 2 Functional Schematic All resistors in ohms, all capacitors in Farads unless otherwise stated. ED1913 RLAC VB = 1.3 VDC 21K R MIC R S = 3.9K - A C S 0.22 1.0 120 - B - C 121 0 9 R GT 5.6K 100K 100K 0.1 R VC R E

-10 -20 -30 -40 -50 -60 -70 -80 -10 -20 -30 -40 -50 -60 -70 -20 -10 0 10 20 30 40 50 TEMPERATURE (oC) -10 -15 -20 RELATIVE TRANSDUCER CURRENT (µA) -20 -10 0 10 20 30 40 50 TEMPERATURE (oC) RELATIVE AMPLIFIER CURRENT (µA) -10 -20 -30 -40 SUPPLY VOLTAGE (V) RELATIVE GAIN (dB) 20 200 2k 20k FREQUENCY (Hz) CS = 0.22µ CS = 0.047µ CS = 0.1µ CS = 0.033µ RELATIVE OUTPUT (dB) Fig. 5. Closed Loop Frequency Response with Various CS Values -12 -16 -20 OUTPUT (dBV) GAIN (dB) 10 100 1K 10K 100K FREQUENCY (Hz) Fig. 7 Preamplifier Open Loop Frequency Response REVISION NOTES Changes to standard packaging. Gennum Corporation assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringement. © Copyright July 1989 Gennum Corporation. Revision Date: July 1992 All rights reserved. Printed in Canada. Fig. 4 I/O Curves at Various RVC Settings -140 -120 -100 -80 -60 -40 INPUT (dBV) RVC = 100K RVC = 47K RVC = 22K RVC = 10K RVC = 3.3K Fig. 8 Transducer Current vs Temperature Fig. 9 Amplifier Current vs Temperature Fig. 6 Gain vs Supply Voltage DOCUMENT IDENTIFICATION PRODUCT PROPOSAL This data has been compiled for market investigation purposes only, and does not constitute an offer for sale. ADVANCE INFORMATION NOTE This product is in development phase and specifications are subject to change without notice. Gennum reserves the right to remove the product at any time. Listing the product does not constitute an offer for sale. PRELIMINARY DATA SHEET The product is in a development phase and specifications are subject to change without notice. DATA SHEET The product is in production. Gennum reserves the right to make changes at any time to improve reliability, function or design, in order to provide the best product possible.