GP34119 GTM, GP34119 Datasheet - Page 3

• Manufacturer Part Number: GP34119
• Description: LOW POWER AUDIO AMPLIFIER
• Manufacturer: GTM

Pin Function Description
Typical Temperature Performance
Input Bias Current (@ Vin)
Total Harmonic Distortion(V
Power Supply Current
(V
(V
Design Guidelines
General
line-powered speakerphones. The circuit provides a differential output (V
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
gain of
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).
offset voltages. The input offset voltage of the two amplifiers swill generally be similar for a particular IC, and therefore nearly cancel each
other at the outputs. Amplifier #1's bias current, however, flows out of V
amount equal to [R
measured with the feedback resistor shown in the Typical Application Circuit, and therefore takes into account the bias current as well as
internal offset voltages of the amplifiers. The bias current is constant with respect to V
FC1 and FC2
dominant at low frequencies, while C1 is dominant at high frequencies, as shown in the graphs of Figures 4 to 7. The required values of
C1 and C2 depend on the conditions of each application. A line powered speakerphone, for example, will require more filtering than a
circuit powered by a well regulated power supply. The amount of rejection is a function of the capacitors, and the equivalent impedance
looking into FC1 and FC2 (listed in the Electrical Characteristics as R
up through the internal 50 k and 125 k resistors. The graph of Figure 1 indicates the turn-on time upon application of V
turn-on time is 60% longer for V
0.4 V above ground, and to with
The GPC34119 is a low power audio amplifier capable of low voltage operation (V
Referring to the block diagram, the internal configuration consists of two identical operational amplifiers. Amplifier # 1 has an open loop
The outputs of both amplifiers are capable of sourcing and sinking a peak current of 200 mA. The outputs can typically swing to within
Power supply rejection is provided by the capacitors (C1 and C2 in the Typical Application Circuit) at FC1 and FC2. C2 is somewhat
In addition to providing filtering, C1 and C2 also affect the turn-on time of the circuit at power-up, since the two capacitors must charge
Symbol
CC
CC
The output dc offset voltage (V
GND
FC2
FC1
V
V
V
CD
Vin
=3V, R
=3V, R
CC
O1
O2
80 dB (at f
L
L
= , CD=0V)
= , CD=2V)
f
x I
Pin
1
2
3
4
5
6
7
8
IB
100 Hz), and the closed loop gain is set by external resistor R
]. V
O2
is shifted positive an equal amount. The output offset voltage, specified in the Electrical Characteristics, is
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 .
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.
Analog ground for the amplifiers. A 1.0uF capacitor at this pin (with a 5.0uF 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.
Amplifier input. This input capacitor and resistor set low frequency rolloff and input impedance. The
feedback resistor is connected to this pin and V
Amplifier Output #1. The dc level is
DC supply voltage (+2V to +16V) is applied to this pin.
Ground pin for the entire circuit.
Amplifier Output #2. This signal is equal in amplitude, but 180° out-of-phase with that at V
The dc level is
CC
CC
O1
1.3 V below V
= 3.0 V, and 20% less for V
Function
-V
=6V, R
O2
) is primarily a function of the feedback resistor (R
L
=32 Pout=125mW, f=1kHz)
(V
CC
CC
, at the maximum current. See Figures 17 and 18 for V
– 0.7)/2.
(-20 : < T
CC
= 9.0V. Turn-off time is < 10 us upon removal of V
A
FC1
(V
< +70 : )
CC
O1
and R
– 0.7)/2.
Description
-V
in
O2
(Pin 4) and through R
FC2
O1
) to the speaker to maximize the available voltage swing at
.
).
CC
f
CC
and R
.
Typical Change
= 2.0 V minimum) such as that encountered in
f
), and secondarily due to the amplifiers' input
i
. The amplifier is unity gain stable, and has a
+0.003
-0.25
-0.03
±40
f
, forcing V01 to shift negative by an
OH
and V
ISSUED DATE :2005/02/18
REVISED DATE :
OL
CC
curves.
Units
uA/ :
.
pA/ :
CC
%/ :
O1
.
of + 6.0 V. The
3/8