Telecoil Preamplifier GC562 - DATA SHEET FEATURES DESCRIPTION • direct coupled telecoil preamplifier The GC562 was designed to allow direct coupling of the telecoil onto the preamplifier without the need of a capacitor. • natural low frequency rolloff to reduce 50/60 Hz hum pickup The DC bias voltage at the output of the unity gain, inverting preamplifier B, precisely matches that of the input of preamp A. When the telecoil is placed between these two pins, no DC current will flow through the coil as the potential at both ends is equal. With stage B configured as unity gain, its output appears as a virtual ground to AC signals. The lower -3 dB corner frequency of the amplifier is set by the ratio of the telecoil resistance to the inductance, given by the equation: RCOIL ƒL = (2π LCOIL) • low current consumption (typ 65 µA) • 34 dB maximum gain STANDARD PACKAGING • Chip (28 x 56 mils) Au Bump With a gain set resistor from the input to output of preamplifier A, a signal inductively coupled into the telecoil via the telephone will produce a signal current to flow through the resistor, thereby producing a voltage at the output of the amplifier. For stability reasons it is recommended that the telecoil amplifier not be configured for more than 34 dB gain, or with a feedback resistor larger than 100 kΩ. VB 2 TREF TIN 1 3 B 4 -A TOUT 5 GND FUNCTIONAL BLOCK DIAGRAM Revision Date: September 1999 Document No. 520 - 93 - 02 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] ABSOLUTE MAXIMUM RATINGS CHIP PIN CONNECTION PARAMETER VALUE / UNITS Supply Voltage 5 VDC Power Dissipation 25 mW Operating Temperature Range -10° C to 40° C Storage Temperature Range -20° C to 70° C TREF VB TIN 2 3 1 6 CAUTION CLASS 1 ESD SENSITIVITY TREF 5 4 GND TOUT ELECTRICAL CHARACTERISTICS Conditions: Frequency = 1 kHz, Temperature = 25°C, Supply Voltage V = 1.3 V B PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 40 65 100 µA -4 0 4 mV DC SPECIFICATIONS Amplifier Current IAMP Telecoil Offset Voltage TVOFF Input Bias Current I BIAS 10 100 200 nA Stage A Source Current ISRC_A 15 30 - µA Stage B Source Current ISRC_B 7 15 - µA VOL 50 300 - mV Output Voltage Swing-Low (Stage A) VP1 - VP3 AC SPECIFICATIONS TREF Output Impedance Z OUT at < 5kHz - 200 - Ω Input Referred Noise IRN NFB 0.2 to 10kHz at 12dB/oct - 1.5 - µV RMS All parameters and switches remain as shown in the Test Circuit unless otherwise stated in CONDITIONS column VPX - actual voltage measured on the pin at given condition (X is pin number). VB=1.3V 2 1 1k 3 B 4 -A 1µ0 5 100k All resistors in ohms, all capacitors in farads unless otherwise stated. Fig. 1 Test Circuit 520 - 93 - 02 2 1µ0 VOUT 2 4 1 3 5 Fig. 2 Functional Schematic Diagram VB 4 4k 5 1µ0 2 MIC REC ED1915 21k 0µ1 1 3 -A B 6 -B 7 TCOIL 3k3 3 GC562 100 4 -A GP509 1 8 2 100k 5 VC 10k All resistors in ohms, all capacitors in farads unless otherwise stated. Fig. 3 Typical Hearing Instrument Application VB=1.3V 2 1k H99966 1 3 B 4 -A VOUT 5 10k All resistors in ohms, all capacitors in farads unless otherwise stated. Fig. 4 Characterization Circuit 3 520 - 93 - 02 -10 20 -20 18 -40 GAIN (dB) OUTPUT (dBV) 19 -30 -50 -60 -70 -80 17 16 15 -90 -100 -140 -120 -100 -80 -60 -40 14 10 -20 100 INPUT (dBV) 20 100k OPEN LOOP VOLTAGE GAIN (dB) 64 18 16 14 12 THD (%) 10k Fig. 6 Frequency Response Fig. 5 I/O Curve 10 8 6 4 2 0 -100 1k FREQUENCY (Hz) -90 -80 -70 -60 -50 -40 56 48 40 1M 10µ 24 1.3V 2.2k 10µ 16 VOUT PREAMP VAC 8 0 -30 1M 32 10 100 INPUT (dBV) 1k 10k 100k FREQUENCY (Hz) Fig. 7 THD vs Input Fig. 8 Stage A Open Loop Voltage Gain 8 PIN DIP PINOUT (For Evaluation Purposes) TREF VB TIN NC 8 7 6 5 1 2 3 4 NC GND TOUT NC 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 Added Au Bump. 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 APRIL 1993 Gennum Corporation. All rights reserved. 520 - 93 - 02 4 Printed in Canada.