SSGSC34119 datasheet(3/9 Pages) SECOS

3 / 9 page

Elektronische Bauelemente

SSGSC34119

Low Power Audio Amplifier

01-June-2002 Rev. A

Page 3 of 9

ELECTRICAL CHARACTERISTICS (Cont’d)

Parameter

Symbol

Test Conditions

Min

Typ

Max

Units

Chip Disable (Pin1)

Input Voltage

VIL

VIH

Low

High

2.0

0.8

VDC

Input Resistance

RCD

VCC = VCD = 16V

175

Power Supply

Power Supply Current

ICC3

ICC16

ICCD

VCC = 3V, RL = ∞ , CD = 0.8V

VCC = 16V, RL = ∞ , CD = 0.8V

VCC = 3V, RL = ∞ , CD = 2.0V

2.7

3.3

4.0

5.0

100

μA

Note: Currents into a pin are positive; currents out of a pin are negative.

PIN FUNCTION DESCRIPTION

Symbol

Description

Chip Disable-Digital input. A Logic “0” (<0.8V) sets normal operation. A Logic “1” (≧2V) sets the

power down mode. Input impedance is nominally 90k

Ω.

FC2

A capacitor at this pin increases power supply rejection, and affects turn-on time. This pin can be

left open if the capacitor at FC1 is sufficient.

FC1

Analog ground for the amplifiers. A 1.0

μF capacitor at this pin (with a 5.0μF capacitor at Pin 2)

provides (typically) 52dB of power supply rejection. Turn-on time of the circuit is affected by the

capacitor on this pin. This pin can be used as an alternate input.

Vin

Amplifier input. This input capacitor and resistor set low frequency roll-off and input impedance.

The feedback resistor is connected to this pin and VO1.

VO1

Amplifier Output #1. The dc level is

≈ (VCC – 0.7)/2.

VCC

DC supply voltage (+2V to +16V) is applied to this pin.

GND

Ground pin for the entire circuit.

VO2

Amplifier Output #2. This signal is equal in amplitude, but 180° out-of-phase with that at VO1. The

dc level is

≈ (VCC – 0.7)/2.

TYPICAL TEMPERATURE PERFORMANCE (-20°C < T

A < + 70°C)

Function

Typical Change

Units

Input Bias Current (@Vin)

±40

pA/°C

Total Harmonic Distortion (VCC = 6V, RL =

Ω, P

out = 125 mW, f = kHz)

+0.003

%/°C

Power Supply Current

(VCC = 3V, RL = ∞ , CD = 0V)

(VCC = 3V, RL = ∞ , CD = 2V)

-0.25

-0.03

μA/°C

Design Guidelines

General

The SGSC34119 is a low power audio amplifier capable of low voltage operation (VCC = 2.0 V minimum) such as that

encountered in line-powered speakerphones. The circuit provides a differential output (VO1-VO2) to the speaker to

maximize the available voltage swing at low voltages. The differential gain is set by two external resistors. Pins FC1 and

FC2 allow controlling the amount of power supply and noise rejection, as well as providing alternate inputs to the

amplifiers. The CD pin permits powering down the IC for muting purposes and to conserve power.

Amplifiers

Referring to the block diagram, the internal configuration consists of two identical operational amplifiers. Amplifier # 1

has an open loop gain of ≧ 80 dB (at f ≦ 100 Hz), and the closed loop gain is set by external resistor Rf and Ri. The

amplifier is unity gain stable, and has a unity gain frequency of approximately 1.5 MHz. In order to adequately cover the

telephone voice band (300 Hz to 3400 Hz), a maximum closed loop gain of 46 is recommended. Amplifier #2 is

internally set to a gain of -1.0(0dB).

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