Document No. 520 - 93 - 02
GC562 - DATA SHEET
FEATURES
direct coupled telecoil preamplifier
natural low frequency rolloff to reduce 50/60 Hz
hum pickup
low current consumption (typ 65
A)
34 dB maximum gain
STANDARD PACKAGING
Chip (28 x 56 mils)
Au Bump
Telecoil Preamplifier
T
IN
B
V
B
4
2
1
3
5
- A
T
OUT
GND
T
REF
FUNCTIONAL BLOCK DIAGRAM
Revision Date: September 1999
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: hipinfo@gennum.com
DESCRIPTION
The GC562 was designed to allow direct coupling of the
telecoil onto the preamplifier without the need of a capacitor.
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:
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 k
.
R
COIL
(2
L
COIL
)
L
=
2
520 - 93 - 02
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
DC SPECIFICATIONS
Amplifier Current
I
AMP
40
65
100
A
Telecoil Offset Voltage
T
VOFF
V
P1
- V
P3
-4
0
4
mV
Input Bias Current
I
BIAS
10
100
200
nA
Stage A Source Current
I
SRC_A
15
30
-
A
Stage B Source Current
I
SRC_B
7
15
-
A
Output Voltage Swing-Low (Stage A)
V
OL
50
300
-
mV
AC SPECIFICATIONS
T
REF
Output Impedance
Z
OUT
at < 5kHz
-
200
-
Input Referred Noise
IRN
NFB 0.2 to 10kHz at 12dB/oct
-
1.5
-
V
RMS
All parameters and switches remain as shown in the Test Circuit unless otherwise stated in CONDITIONS column
V
PX
- actual voltage measured on the pin at given condition (X is pin number).
CAUTION
CLASS 1 ESD SENSITIVITY
ABSOLUTE MAXIMUM RATINGS
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
Conditions: Frequency = 1 kHz, Temperature = 25
C, Supply Voltage V
B
= 1.3 V
ELECTRICAL CHARACTERISTICS
Fig. 1 Test Circuit
All resistors in ohms, all capacitors
in farads unless otherwise stated.
CHIP PIN CONNECTION
10
B
V
B
=1.3V
100k
4
2
1
3
5
- A
10
V
OUT
1k
T
REF
V
B
T
IN
T
REF
GND T
OUT
1 2 3
6
5 4
3
520 - 93 - 02
1
3
2
4
5
All resistors in ohms, all capacitors
in farads unless otherwise stated.
Fig. 3 Typical Hearing Instrument Application
All resistors in ohms, all capacitors
in farads unless otherwise stated.
Fig. 4 Characterization Circuit
Fig. 2 Functional Schematic Diagram
T
COIL
MIC
B
GC562
V
B
21k
10
10k
2
6
4
3
1
7
4
2
1
3
5
- A
01
4k
8
100k
VC
GP509
- A
- B
REC
ED1915
100
5
3k3
H99966
B
V
B
=1.3V
10k
4
2
1
3
5
- A
V
OUT
1k
4
520 - 93 - 02
64
56
48
40
32
24
16
8
0
20
18
16
14
12
10
8
6
4
2
0
-100 -90 -80 -70 -60 -50 -40 -30
INPUT (dBV)
THD (%)
Fig. 7 THD vs Input
10
100 1k
10k 100k
FREQUENCY (Hz)
Fig. 8 Stage A Open Loop Voltage Gain
OPEN LOOP VOLTAGE GAIN (dB)
Fig. 5 I/O Curve
OUTPUT (dBV)
-140 -120 -100
-80
-60
-40
-20
INPUT (dBV)
10
100 1k
10k 100k
FREQUENCY (Hz)
Fig. 6 Frequency Response
GAIN (dB)
20
19
18
17
16
15
14
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
1 2 3 4
T
REF
V
B
T
IN
NC
NC GND T
OUT
NC
8 7 6
5
8 PIN DIP PINOUT
(For Evaluation Purposes)
1.3V
PREAMP
10
10
V
AC
2.2k
1M
1M
V
OUT
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.
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. Printed in Canada.
REVISION NOTES:
Added Au Bump.
GENNUM CORPORATION
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
GENNUM JAPAN CORPORATION
C-101, Miyamae Village, 2-10-42 Miyamae, Suginami-ku, Tokyo 168-0081,
Japan Tel. +81 (3) 3334-7700 Fax: +81 (3) 3247-8839
PDF 
ZIP