Class A Amplifier with 2 Independent Gain Blocks LP508 DATA SHEET FEATURES DESCRIPTION • 1 µV input referred noise The LP508 is an 8 pin Class A amplifier utilizing Gennum's proprietary low voltage bipolar JFET technology. It consists of • 1.0 to 5 VDC operating range 2 single ended, low noise inverting gain blocks. The first block • 61 dB typical gain (adjustable) has a typical open loop gain of 50 dB, with the closed loop gain • 0.28 to 2.0 mA range of transducer current set by the ratio of the feedback resistor to the the source • 1 % electrical distortion impedance. The second block has the output transistor bias • the first and second blocks can be DC coupled set by RE and VRE at pin 7 which is 27 mV. • 4.0 kΩ microphone decoupling resistor, on-chip • 100 Hz to 50 kHz frequency response Typically, the gain of the first block is set to 29 dB, with the • volume control range >40 dB second block at 32 dB, giving a total gain of 61 dB. STANDARD PACKAGING • • • • 8 pin MICROpac 8 pin PLID ® 8 pin SLT Chip (59 x 53 mils) Au Bump VB 5 VMIC 4 RMIC 18K 3 A IN 6 - A - B 7 B OUT RE RE 1 A OUT 8 B IN 2 GND BLOCK DIAGRAM Revision Date: January 2001 Document No. 500 - 71 - 9 GENNUM CORPORATION P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 tel. +1 (905) 632-2996 Web Site: www.gennum.com E-mail: [email protected] PIN CONNECTION ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE/UNITS Supply Voltage 5 V DC Power Dissipation 25 mW Operating Temperature Range V MIC A IN B R E 1 A OUT -20°C to 70° C V B OUT GND -10°C to 40° C Storage Temperature Range 5 4 8 B IN CAUTION CLASS 1 ESD SENSITIVITY ELECTRICAL CHARACTERISTICS Conditions: Frequency = 1 kHz, Temperature = 25°C, Supply Voltage VB = 1.3 VDC PARAMETER SYMBOL CONDITIONS MIN TYP MAX Gain (Closed Loop) A CL Distortion VOUT=500mV RMS 57 61 65 dB THD VOUT=500mV RMS - 1 4 % Amplifier Current IAMP IAMP= I A + I MIC 125 195 255 µA Transducer Current ITRANS H RE = 27.5 1.1 1.3 1.7 mA Transducer Current ITRANS L RE = ∞ 200 275 350 µA Input Referred Noise IRN NFB 0.2 to 10 kHz at 12 dB/oct. - 1 2 µV - - 22 Ω Stable with Battery Resistance to Input Bias Current (pin 3) IB -50 0 50 nA On Chip Emitter Resistor RE - 100 - Ω Emitter Bias Voltage (Pin 7) VRE - 27 - mV Microphone Decoupling Resistor R MIC - 4 - kΩ All parameters and switches remain as shown in Test Circuit unless otherwise stated in "Conditions" column VB=1.3 VDC IAMP RB= 4.75 5 RMIC IMIC VOUT 4 RS 3.3K 6 -A -B 3 V IN 1kHz RL=1K 18K C1 10 33K ITRANS 7 RE IB RE =27.5 C2 10 1 8 RFA =100K C3 1.0 All resistors in ohms, all capacitors in µF unless otherwise stated Fig. 1 Test Circuit 500 - 71 - 9 UNITS 2 2 5 RMIC 18K 6 8 1 BASE CURRENT COMPENSATION 33K 7 3 RE Patent No.154104 2 All resistors in ohms, all capacitors in µF unless otherwise stated Fig. 2 Functional Schematic VB = 1.3 VDC 5 RMIC RL = 6K 4 1.0 18K CS -A RS 3.9K 0.22 6 -B 3 7 RE 1 RVC Gain of stage A = 20Log10 RVC RS 8 2 100K Gain of stage B = 20 Log10 RL // 18K RE For low impedance receivers, a capacitor from pin 6 to pin 2 may be required for stability. All resistors in ohms, all capacitors in µF unless otherwise stated Fig. 3 Typical Hearing Aid Circuit 3 500 - 71 - 9 4 10 2 0 RVC = 100K RVC = 47K OUTPUT (dBV) -20 CS = 0.22µF 0 RELATIVE OUTPUT (dB) -10 RVC = 22K -30 RVC = 10K -40 RVC = 3.3K -50 -60 -70 -2 CS = 0.1µF -4 -6 CS = 0.047µF -8 CS = 0.033µF -10 -12 -14 -16 -80 -18 -90 -130 -20 -110 -90 -70 -60 -40 -20 20 20000 INPUT (dBV) FREQUENCY (Hz) Fig. 4 I/O Characteristics at Various RVC Values Fig. 5 Frequency Response at Various CS Values 10 60 5 55 50 -5 -10 GAIN (dB) RELATIVE GAIN (dB) 0 -15 -20 45 40 35 -25 30 -30 25 -35 -40 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 20 1.4 10 100 1K RELATIVE TRANSDUCER CURRENT (µA) RELATIVE AMPLIFIER CURRENT (µA) 40 30 20 10 0 -10 -20 -30 -40 -50 -10 0 10 20 30 100K Fig. 7 Preamplifier A Open Loop Frequency Response Fig. 6 Gain vs Supply Voltage -60 -20 10K FREQUENCY (Hz) SUPPLY VOLTAGE (VDC) 40 50 30 20 10 0 -10 -20 -30 -40 -50 -20 -10 TEMPERATURE (˚C) 0 10 20 30 40 50 TEMPERATURE (˚C) Fig. 9 Transducer Current vs Temperature Fig. 8 Amplifier Current vs Temperature GENNUM CORPORATION DOCUMENT IDENTIFICATION: 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. MAILING ADDRESS: P.O. Box 489, Stn. A, Burlington, Ontario, Canada L7R 3Y3 Tel. +1 (905) 632-2996 Fax +1 (905) 632-2814 SHIPPING ADDRESS: 970 Fraser Drive, Burlington, Ontario, Canada L7L 5P5 REVISION NOTES: GENNUM JAPAN CORPORATION Changes to standard packaging information C-101, Miyamae Village, 2-10-42 Miyamae, Suginami-ku, Tokyo 168-0081, Japan Tel. +81 (3) 3334-7700 Fax: +81 (3) 3247-8839 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 May 1984 Gennum Corporation. All rights reserved. 500 - 71 - 9 4 Printed in Canada.