Low Distortion AGC Compression Amplifier LP502 CUSTOM DATA SHEET FEATURES By using RGT (see test circuit) to vary the value of this current controlled resistance, the amplifier gain and compression threshold can be controlled over a range of 60 dB. • adjustable gain from 0 to 60 dB • 0.94 V DC voltage regulator on-chip The AGC current is derived from a full wave rectifier driven by a differential amplifier. The attack time of the AGC circuit is fixed at less than 1 ms. The release time is adjustable from 40 to 500 ms by selecting the value of an external capacitor (C3). • attack time fixed at less than 1 ms • release time adjustable from 40 to 500 ms • low input referred noise 1.2 µV • <1 % distortion at 10 mVRMS output Internally, a series shunt voltage regulator produces a 0.94 V DC regulated output voltage. This provides a bias for electret microphones and permits circuit operations over a wide range of supply voltages, 1.05 to 3 VDC for LP502 without any degradation of electrical performances. • operates from 1.05 to 3 VDC STANDARD PACKAGING • 8 pin MICROpac • 8 pin PLID ® • Chip (64 x 62 mils) Au Bump DESCRIPTION The LP502 is a compression (AGC) preamplifier that consists of a single-ended input inverting amplifier, with an internal current controlled resistance connected between input and output. As compared to the LD502, the LP502 incorporates an additional diode between the amplifier output and the AGC filter point. This “attack diode” is responsible for precharging the AGC filter point, which enables quicker attack time and helps to reduce the gain overshoot (during transients) that is observed in the LD502 with certain combinations of AGC input coupling and filter capacitors. However, with this diode connected, some level of AGC is always present with higher output levels even when the AGC input is disconnected. Therefore the LP502 cannot be used as a “pure” linear amplifier. VB GAIN SET 7 2 VREG 4 VOLTAGE REGULATOR 1 A OUT AMPLIFIER A IN 3 FULL WAVE RECTIFIER 8 AGC IN 6 5 AGC FILTER GND BLOCK DIAGRAM Patented 1985 Canada 1183580 Patent Pending Europe 83.300836.0 USA 4506169 Japan 58-06886 Document No. HP2802-1 GENNUM CORPORATION P.O. Box 489, Stn A, Burlington, Ontario, Canada L7R 3Y3 tel. (905) 632-2996 fax: (905) 632-5946 Gennum Japan Corporation:C-101 Mi yamae Vill age, 2–10–42 Mi yamae, Suginami–ku, Tokyo 168-0081, Japan tel. (03) 3334-7700 fax (03) 3247-8839 ABSOLUTE MAXIMUM RATINGS PIN CONNECTION PARAMETER VALUE/UNITS Supply Voltage 3 V DC Power Dissipation 25 mW A OUT Operating Temperature Range -10°C to 50° C VREG Storage Temperature Range -20°C to 70° C A IN GAIN SET 5 4 AGC FILTER AGC IN VB 1 GND 8 CAUTION CLASS 1 ESD SENSITIVITY ELECTRICAL CHARACTERISTICS Conditions: Frequency = 1 kHz, Temperature = 25°C, Supply Voltage V B = 1.3 VDC PARAMETER SYMBOL Gain AV CONDITIONS MIN TYP 38 41 46 dB 7.5 12 15.5 mV VOUT = 11.0 mV - 1 2.9 % VIN = 6.32mV, S1 closed - 1 2.2 % S2 closed,NFB 0.2 to 10 kHz at 12 dB/Oct - 1.2 2.2 µV VIN = 0.1 to 6.32 mV, S1 closed 2 5 8 dB µA VOUT = 11.0 mV, 20 Log ( V OUT ) MAX UNITS V IN Output Level VOHIGH Distortion -Linear THD - AGC Input Referred Noise IRN Compression Function Ratio VIN = 6.32 mV, S1 closed Total Amplifier Current IAMP 160 310 380 Regulated Voltage VREG 0.890 0.940 0.990 Supply Rejection PSRR 51 60 - All parameters and switches remain as shown in Test Circuit unless otherwise stated in "Conditions" column ITOT RGT 130k VB= 1.3 VDC 7 2 C1 0.47 4 VOLTAGE REGULATOR C5 1.0 3 1 AMP VOUT RTH 0Ω RS= 3.5k S1 FULL WAVE RECTIFIER S2 C4 0.1 RM 33K C2 1.0 8 5 VIN C3 1.0 All resistors in ohms, all capacitors in microfarads unless otherwise stated Fig. 1 Test Circuit HP2802-1 6 2 RL 10K VDC dB GAIN TRIM VB=1.3 VDC 4.7 4.7 500k 7 4 1 VOLTAGE REGULATOR 2 4.7 4 LP502 LC549 6 VC =10k 5 0.1 0.1 AMP 1 2 RL=400 TYP 3 RS 3.9k 0.1 FULL WAVE RECTIFIER 8 6 3 5 8 7 NC 0.047 0.1-1.0 All resistors in ohms, all capacitors in microfarads unless otherwise stated Fig. 2 LP502/LC549Hearing Instrument Application GAIN TRIM VB=1.3 VDC 500k 7 2 4.7 4 LP502 25k 2 0.1 0.1 AMP 33k 3 1 RS 3.9k 6 18k BK1606 7 Z=1k 13.5k 2k 0.1 VC 10k 3 8 1 5 0.1 FULL WAVE RECTIFIER 8 4 LE507 VOLTAGE REGULATOR 6 5 RE=33 0.47 All resistors in ohms, all capacitors in microfarads unless otherwise stated Fig. 3 LP502/LE507 Hearing Instrument Application 3 HP2802-1 100 100 10 OUTPUT (mV) OUTPUT (mV) RTH=50kΩ RTH=22kΩ RTH=10kΩ 10 RTH=0kΩ 1 0.01 0.1 1.0 1 0.1 0.01 10 0.1 1.0 INPUT (mV) INPUT (mV) Fig. 4 I/O Characteristics at Various RTH Values Fig. 5 I/O Characteristics at Various RGT Values 10 4 100 2 RELATIVE OUTPUT (dB) 0 RTH=0 OUTPUT (mV) RGT=130kΩ RGT=82kΩ RGT=68kΩ RGT=47kΩ VB=3 VDC 10 VB=1.3 VDC -2 CS=0.22 µF CS=0.1 µF -4 -6 -8 CS=0.047 µF -10 -12 CS=0.033 µF -14 -16 -18 0.1 0.01 0.1 1.0 -20 20 10 200 2K 20k FREQUENCY (Hz) INPUT (mV) Fig. 6 Effects of Supply Voltage Variation Fig. 7 Frequency Response at Various CS Values 4.0 THD (%) 3.0 2.0 DOCUMENT IDENTIFICATION PRODUCT PROPOSAL This data has been compiled for market investigation purposes only, and does not constitute an offer for sale. 1.0 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. 0.0 0.0 5.0 10.0 15.0 20.0 25.0 OUTPUT (mV) Fig. 8 Total Harmonic Distortion vs Output Level PRELIMINARY DATA SHEET The product is in a preproduction 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. 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 August 1997 Gennum Corporation. All rights reserved. Printed in Canada. HP2802-1 4