Gennum Corporation GC562 Datasheet

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 µA)

• 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. [phone]

Web Site: www.gennum.com E-mail: [e-mail]

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 kΩ.

R

COIL

(2π L

COIL

)

ƒL =

2

520 - 93 - 02

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC SPECIFICATIONS

Amplifier Current I

AMP

40 65 100 µA

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 - µA

Stage B Source Current I

SRC_B

715 -µA

Output Voltage Swing-Low (Stage A) V

OL

50 300 - mV

AC SPECIFICATIONS

T

REF

Output Impedance Z

OUT

at < 5kHz - 200 - Ω

Input Referred Noise IRN NFB 0.2 to 10kHz at 12dB/oct - 1.5 - µVRMS

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 VB = 1.3 V

ELECTRICAL CHARACTERISTICS

Fig. 1 Test Circuit

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

CHIP PIN CONNECTION

1µ0

B

V

B

=1.3V

100k

4

2

1

3

5

- A

1µ0

V

OUT

1k

T

REF

V

B

T

IN

T

REF

GND T

OUT

1 2 3

6 5 4