LS505

LS505 GENNUM

Document overview

• PDF pages: 5

Technical content

Page 1

FEATURES

• 72 dB typical gain
• 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
• requires only 4 external parts for operation

STANDARD PACKAGING

• 8 pin MINIpac
• 8 pin MICROpac
• 8 pin PLID®
• 8 pin SLT
• Chip (56 x 55 mils)

VMIC VB 4 8

2.2k

+

I/P 6

-

100

RVC 5

7

GND

High Gain Class A Amplifier

with Peak Clipping

LS505 DATA SHEET

DESCRIPTION

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.

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.

The input stage and microphone are biased by an internal 2.2 kΩ decoupling resistor to increase battery line signal rejection.

MPO 1

O/P 3

33k

200

2 RE

BLOCK DIAGRAM

All resistors in ohms, all capacitors in farads unless otherwise stated.

Revision Date: January 1996

Document No. 500 - 20 - 11

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, Miyamae Village, 2–10–42 Miyamae, Suginami–ku Tokyo 168, Japan tel. (03) 3334-7700 fax (03) 3247-8839

Page 2

PIN CONNECTION

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

Conditions: Temperature 25 oC, Supply Voltage VB = 1.55 VDC

All switches and parameters remain as shown in test circuit unless stated in condition column

Page 3

RB = 4.7 VB = 1.5 VDC

All resistors in ohms, all capacitors in µF unless otherwise stated

Fig. 1 Test Circuit

VMIC

INPUT

VOLUME

CONTROL

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

Page 4

All resistors in ohms, all capacitors in farads unless otherwise stated

Fig. 3 Typical Hearing Aid Applications

10 50 100

500 1k

5k 10k

EXTERNAL RESISTANCE (Ω)

Fig. 4 Volume Control Range vs RE

EXTERNAL RESISTANCE RE (Ω)

Fig. 6 Load Current vs External Resistance

RE Ω

Fig. 5 GM vs RE Ω

Ω

INPUT (dBSPL)

Fig. 7 I/O Characteristics

Page 5

RVC (Ω)

Fig. 8 Relative Voltage Gain vs Volume Control Resistance

0.8 1.0 1.2 1.4 1.6 1.8

SUPPLY VOLTAGE (V)

Fig. 10 Amplifier Current vs Supply Voltage

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

BATTERY RESISTANCE RB (Ω)

Fig. 9 Relative Voltage Gain vs Battery Resistance

0.8 1.0 1.2 1.4 1.6 1.8 SUPPLY VOLTAGE (V)

Fig. 11 Load Current vs Supply Voltage

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.