High Gain Class A Amplifier with Peak Clipping LS505 DATA SHEET FEATURES DESCRIPTION • 72 dB typical gain The LS505 is a low voltage, monolithic integrated circuit amplifier comprised of an operational amplifier driving a single transistor Class A output stage with open collector. Also included are a pair of complementary Schottky diodes which provide the capability for symmetrical peak clipping in a feedback configuration. • 0.2 to 2.0 mA of transducer current adjustment • 43 dB range of feedback volume control • 1.0 to 1.6 V supply operating range • Schottky diodes provide symmetrical peak clipping An internal negative feedback loop ensures a stable operating point for the output stage over the designed operating voltage. This also permits trimming of the output current with the use of a single external resistor. • requires only 4 external parts for operation STANDARD PACKAGING • 8 pin MINIpac The input stage and microphone are biased by an internal 2.2 kΩ decoupling resistor to increase battery line signal rejection. • 8 pin MICROpac • 8 pin PLID® • 8 pin SLT • Chip (56 x 55 mils) VMIC 8 VB MPO 4 1 O/P 2.2k I/P 3 + 6 33k 100 RVC 200 5 7 GND 2 RE BLOCK DIAGRAM All resistors in ohms, all capacitors in farads unless otherwise stated. Revision Date: January 1996 GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 Japan Branch: A-302, M i yamae Vi l l age, 2–10–42 M i yamae, Suginami–ku Tokyo 168, Japan Document No. 500 - 20 - 11 tel. (905) 632-2996 fax: (905) 632-5946 tel. (03) 3334-7700 fax (03) 3247-8839 PIN CONNECTION ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE & UNITS Supply Voltage V B 3V Power dissipation -10 to +40 °C Storage Temperature -20 to +70 °C R VC O/P 25 mW Operating Temperature 5 4 I/P R E GND MPO V MIC 1 8 CAUTION CLASS 1 ESD SENSITIVITY ELECTRICAL CHARACTERISTICS Conditions: Temperature 25 o C, Supply Voltage VB = 1.55 VDC PARAMETER SYMBOL CONDITION MIN TYP MAX VO = 0.707 VRMS 68 72 76 - 0.07 - 180 210 280 - -0.002 - 1.3 1.5 1.9 UNITS Gain ACL Temperature Coefficient of Gain ηA Amplifier Current IAMP Temperature Coefficient of Current ηΙ Transducer Current ITRANS Total Harmonic Distortion THD VO = 0.707 VRMS - 2 5 Input Referred Noise IRN NFB 0.2 to 10 kHz at 12 dB/oct - 1.2 2.0 µVRMS Battery Resistance Stability RB = 22Ω - - 22 Ω Volume Control Range RVC = 100 to 100.1 kΩ S1 open 36 43 - dB - 27 - kΩ Low - 100 - Hz High - 5K - Hz 0.125 0.19 0.275 VRMS - 0.16 - dB/Ω - 42.5 - mV Input Impedance (Pin 6) RIN Frequency Response (-3 dB) Maximum Output S2 closed Gain Dependence of RB Emitter Bias Voltage (Pin 2) VRE All switches and parameters remain as shown in test circuit unless stated in condition column 500 - 20 - 11 2 dB dB/oC µA mA/oC mA % RB = 4.7 10 + + VB = 1.5 VDC VO 10 S2 1k 8 RS 3.9k 2.2k 1 4 3 0.033 IL + 6 S1 33k 200 100 100k + 10 100 5 2 7 RE 33 All resistors in ohms, all capacitors in µF unless otherwise stated Fig. 1 Test Circuit VB 4 2.2k MPO VMIC 1 8 30k 27k OUTPUT 3 INPUT 6 100 33k VOLUME CONTROL 2 RE 200 5 GND 7 All resistors in ohms, all capacitors in farads unless otherwise stated U.S. Patent No. 4,034,306 - Patented in other countries Fig. 2 Functional Schematic 3 500 - 20 - 11 CMPO + V =1.35VDC B RMPO 10 10k 1.0 8 4 1 1k 2.2k 3 6 + 0.033 LS505 100 - 5 RVC 33k 200 100k LS505 2 7 + 10 R E 56 All resistors in ohms, all capacitors in farads unless otherwise stated 7 46 6 45 5 44 4 ) 47 Ω gm ( 43 3 42 2 41 1 40 10 50 100 500 1k 5k 0 10k 10 50 100 500 Fig. 5 GM Fig. 4 Volume Control Range vs RE 3.5 5k 10k 100 110 vs RE Ω 130 DIODES DISCONNECTED 3.0 120 OUTPUT (dBSPL) 2.5 L LOAD CURRENT I (mA) 1k RE Ω EXTERNAL RESISTANCE (Ω) Ω VOLUME CONTROL RANGE (dB) Fig. 3 Typical Hearing Aid Applications 2.0 1.5 1.0 110 100 90 0.5 0 10 80 50 100 500 1k 5kk 10k 40 50 60 70 80 Fig. 7 I/O Characteristics Fig. 6 Load Current vs External Resistance 500 - 20 - 11 30 INPUT (dBSPL) EXTERNAL RESISTANCE RE (Ω) 4 90 6 RELATIVE VOLTAGE GAIN (dB) RELATIVE VOLTAGE GAIN (dB) 0 -10 -20 -30 -40 -50 10 100 1k R VC 5 4 3 2 1 10k 1 100 BATTERY RESISTANCE R (Ω) B Fig. 8 Relative Voltage Gain vs Volume Control Resistance Fig. 9 Relative Voltage Gain vs Battery Resistance 250 2.5 200 2.0 L LOAD CURRENT I (mA) AMPLIFIER CURRENT (µA) 10 (Ω) 150 100 50 0 1.5 1.0 0.5 0 0.8 1.0 1.2 1.4 1.6 0.8 1.8 1.0 1.2 1.4 1.6 1.8 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) Fig. 10 Amplifier Current vs Supply Voltage Fig. 11 Load Current vs Supply Voltage 74 GAIN (dB) 72 70 68 66 64 0.8 1.0 1.2 1.4 1.6 1.8 SUPPLY VOLTAGE (V) Fig. 12 Gain vs Supply Voltage REVISION NOTES Au bump removed 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 October 1977 Gennum Corporation. All rights reserved. Printed in Canada. 5 500 - 20 - 11 500 - 20 - 11 6