LS505 DATA SHEET
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)
High Gain Class A Amplifier
with Peak Clipping
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 k
decoupling resistor to increase battery line signal
rejection.
Revision Date: January 1996
100
-
+
7
4
33k
200
5
6
I/P
GND
R
VC
8
1
2.2k
VB
MPO
V
MIC
3
O/P
R
E
2
BLOCK DIAGRAM
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, M i yamae Vi l l age, 21042 M i yamae, Suginamiku Tokyo 168, Japan tel. (03) 3334-7700 fax (03) 3247-8839
Document No. 500 - 20 - 11
All resistors in ohms, all capacitors in farads unless otherwise stated.
500 - 20 - 11
2
PARAMETER SYMBOL
CONDITION MIN TYP
MAX
UNITS
Gain
A
CL
V
O
= 0.707 V
RMS
68
72
76
dB
Temperature Coefficient of Gain
A
-
0.07
-
dB/
o
C
Amplifier Current
I
AMP
180
210
280
A
Temperature Coefficient of Current
-
-0.002
-
mA/
o
C
Transducer Current
I
TRANS
1.3
1.5
1.9
mA
Total Harmonic Distortion
THD
V
O
= 0.707 V
RMS
-
2
5
%
Input Referred Noise
IRN
NFB 0.2 to 10 kHz at 12 dB/oct
-
1.2
2.0
V
RMS
Battery Resistance Stability
R
B
= 22
-
-
22
Volume Control Range
R
VC
= 100 to 100.1 k
S1 open
36
43
-
dB
Input Impedance (Pin 6)
R
IN
-
27
-
k
Frequency Response (-3 dB)
Low
-
100
-
Hz
High
-
5K
-
Hz
Maximum Output
S2 closed
0.125
0.19
0.275
V
RMS
Gain Dependence of RB
-
0.16
-
dB/
Emitter Bias Voltage (Pin 2)
V
RE
-
42.5
-
mV
ABSOLUTE MAXIMUM RATINGS
PARAMETER
VALUE & UNITS
Supply Voltage
3 V
Power dissipation
25 mW
Operating Temperature
-10 to +40
C
Storage Temperature
-20 to +70
C
CAUTION
CLASS 1 ESD SENSITIVITY
1
4
5
8
R
E
I/P
GND
V
MIC
MPO
O/P
V
B
PIN CONNECTION
R
VC
ELECTRICAL CHARACTERISTICS
Conditions: Temperature 25
o
C, Supply Voltage V
B
= 1.55 VDC
All switches and parameters remain as shown in test circuit unless stated in condition column
500 - 20 - 11
3
+
R
S
3.9k
100
-
+
1
5
4
8
33k
200
R
E
33
2.2k
6
3
2
7
100
100k
S1
10
+
0.033
10
+
10
S2
V
B
= 1.5 VDC
R
B
= 4.7
1k
I
L
V
O
All resistors in ohms, all capacitors in
F unless otherwise stated
Fig. 1 Test Circuit
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
MPO
OUTPUT
VB
RE
GND
200
33k
VOLUME
CONTROL
INPUT
100
V
MIC
30k
2.2k
27k
6
5
3
2
4
7
8
1
500 - 20 - 11
4
R
E
0.033
V
B
10
2
3
=1.35VDC
+
100
8
5
6
7
1k
10
+
4
LS505
33k
+
LS505
1
-
200
R
VC
2.2k
C
MPO
56
R
MPO
100k
10k
1.0
All resistors in ohms, all capacitors in farads unless otherwise stated
Fig. 3 Typical Hearing Aid Applications
47
46
45
44
43
42
41
40
10
50
100
500
1k
5k 10k
Fig. 4 Volume Control Range vs R
E
EXTERNAL RESISTANCE (
)
VOLUME CONTROL RANGE (dB)
Fig. 5 GM vs R
E
gm ( )
7
6
5
4
3
2
1
0
10
50
100
500 1k 5k 10k
EXTERNAL RESISTANCE R
E
(
)
Fig. 6 Load Current vs External Resistance
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
LOAD CURRENT
I
L
(mA)
10 50 100 500 1k 5kk 10k
R
E
130
120
110
100
90
80
Fig. 7 I/O Characteristics
30 40 50 60 70 80 90 100 110
DIODES
DISCONNECTED
INPUT (dBSPL)
OUTPUT
(dBSPL)
500 - 20 - 11
5
Fig. 8 Relative Voltage Gain vs
Volume Control Resistance
RELATIVE VOLTAGE GAIN (dB)
1 10 100
BATTERY RESISTANCE R
B
(
)
R
VC
(
)
Fig. 9 Relative Voltage Gain vs
Battery Resistance
250
200
150
100
50
0
AMPLIFIER CURRENT (
A)
0.8 1.0 1.2 1.4 1.6 1.8
SUPPLY VOLTAGE (V)
Fig. 10 Amplifier Current vs Supply Voltage
2.5
2.0
1.5
1.0
0.5
0
LOAD CURRENT
I
L
(mA)
0.8
1.0
1.2
1.4 1.6 1.8
SUPPLY VOLTAGE (V)
Fig. 11 Load Current vs Supply Voltage
0.8
1.0
1.2
1.4 1.6 1.8
SUPPLY VOLTAGE (V)
RELATIVE VOLTAGE GAIN (dB)
Fig. 12 Gain vs Supply Voltage
74
72
70
68
66
64
0
-10
-20
-30
-40
-50
10 100 1k 10k
GAIN (dB)
6
5
4
3
2
1
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.
REVISION NOTES
Au bump removed
500 - 20 - 11
6
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