PJ34119
Low Power Audio Ampllfier
1-10
2003/10.ver.A
Characteristic
Value
Unit
Supply Voltage
Maximum Output Crrent at V
O1
,V
O2
Maximum Voltage
@Vin,FC1,FC2,CD
Applied Output Voltage to VO1,VO2
when disabled
Junction Temperature
-1.0 to 18
250
-1.0,Vcc+1.0
-1.0,Vcc+1.0
-55,+140
Vdc
mA
Vdc
NOTE:ESD data available upon request.
he PJ34119 is a low power audio amplifier intergrated circuit
intended primarilyfor telephone applications such as
in speakerphones. It provides differential speaker outputs to
maximize output swing at low supply coltages(2.0V minimum).
Coupling capacitors to the speaker are not required. Open loop gain
is 80dB , and the closed loop gain is set with two external resistors.
A chip Disable pin permits powering down and/or muting the input
signal. The PJ34119 is available in standard DIP-8, SOP-8
package.
Low Quiescent Supply Current(2.7mA Typ)for Battery
powered Applications.
Wide Operating Supply Voltage Range(2.0V to 16V), Allows
Telephone Line Powered Applications.
Chip Disable Input to Power Down the IC
Low Power-Down Quiescent Current(65A Typ)
Drives a Wide Range of Speaker Loads(8.0 and Up)
Output Power Exceeds 250mW with 32 Speaker
Low Total Harmonic Distortion(0.5% Typ)
Gain Adjustable from <0 dB to >46dB for Voice Band
Requires Few External Components.
T
Device
Operating Temperature
Package
PJ34119CD
DIP-8
PJ34119CS
-20 to +85
SOP-8
FEATURES
DIP-8
SOP-8
Pin : 1.Cd 5.Vo1
2.Fc2 6.Vcc
3.Fc1 7.Gnd
4.Vin 8.Vo2
ORDERING INFORMATION
ABSOLUTE MAXIMUM RATINGS ( T
a
= 25
)
BLOCK DIAGRAM AND SIMPLIFIED APPLICATION
RECOMMENDED OPERATING CONDITIONS
PJ34119
Low Power Audio Ampllfier
2-10
2003/10.ver.A
Characteristics Symbol
Min
Max
Unit
Supply Voltage
Voltage@CD(Pin 1)
V
CC
V
CD
+2.0
0
+16
V
CC
Vdc
Vdc
Load Impedance
R
L
8.0
-
Peak Load Current
I
L
-
200
mA
Differential Gain (5.0KHz Bandwidth)
AVD
0
46
dB
Ambient Temperature
T
A
-20
+70
Characteristics Symbol
Min
Typ
Max Unit
AC Input Resistance(@ Vin)
Ri
-
>30
-
M
Open Loop Gain(Amplifier #1, f<100Hz)
AVOL1
80
-
-
dB
Closed Loop Gain(Amplifier #2, Vcc=6.0V,f=1KHz,
R
L
=32)
AV2 -0.35 0 +0.35 dB
Gain Bandwidth Product
GBW
-
1.5
-
MHz
Output Power:
Vcc=3.0V,R
L
=16,THD
10%
Vcc=6.0V,R
L
=32,THD
10%
Vcc=12V,R
L
=100,THD
10%
Pout3
Pout6
Pout12
55
250
400
-
-
-
-
-
-
mW
Total Hamonic Distortion(f=1KHz)
(Vcc=6.0V, R
L
=32,Pout=125mW)
(Vcc
3.0V, R
L
=8.0,Pout=20mW)
(Vcc
12V, R
L
=32,Pout=200mW)
THD -
-
-
0.5
0.5
0.6
1.0
-
-
%
Power Supply Rejection(Vcc=6.0V,
Vcc=3.0V)
(C1=
, C2=0.01F)
(C1=0.1
F,C2=0,f=1.0KHz)
(C1=1.0
F,C2=5.0F,f=1.0KHz)
PSRR 50
-
-
-
12
52
-
-
-
dB
Differential Muting
(Vcc=6.0V,1.0KHz
f20KHz,CD=2.0V)
GMT - >70 - dB
AMPLIFIERS(DC CHARACTERISTICS)
Output DC Level@V
O1
,V
O2
, ,R
L
=16(R
f
=75K)
V
CC
=3.0V
Vcc=6.0V
Vcc=12V
Vo(3)
Vo(6)
Vo(12)
1.0
-
-
1.15
2.65
5.56
1.25
-
-
Vdc
Output Level
High(Iout=-75mA,2.0
Vcc16V)
Low(Iout=75mA, 2.0
Vcc16V)
V
OH
V
OL
-
-
Vcc-1.0
0.16
-
-
Vdc
Output DC Offset Voltage(V
O1
-V
O2
)
(Vcc=6.0V,RL=75K,R
L
=32)
Vo -30 0 +30 mV
Input Bias Current@Vin(Vcc=6.0V)
f
IB
-
-100
-200
nA
Equivalent Resistance
@FC1(Vcc=6.0V)
@FC2(Vcc=6.0V)
R
FC1
R
FC2
100
18
150
25
220
40
K
CHIP DISABLE(Pin1)
Input Voltage
Low
High
V
IL
V
IH
-
2.0
-
-
0.8
-
Vdc
Input Resistance(Vcc=V
CD
=16V) R
CD
50 90 175
K
POWER SUPPLY
Power Supply Current
(Vcc=3.0V,R
L
=
,CD=0.8V)
(Vcc=16V,R
L
=
,CD=0.8V)
(Vcc=3.0V,R
L
=
,CD=2.0V)
I
CC3
I
CC16
I
CCD
-
-
-
2.7
3.3
65
4.0
5.0
100
mA
mA
A
NOTE:Current into are positive,current out of a pin are negative.
ELECTRICAL CHARACTERISTICS
(T
A
=25,unless otherwise noted)
PJ34119
Low Power Audio Ampllfier
3-10
2003/10.ver.A
Symbol Pin
Description
CD 1
Chip Distable-Digital input. A Logic"0"(<0.8V) sets normal operation. A logic"I"2.0Vsets
the power down mode. Input impedance is nominally 90K
FC2
2
A capacitor at this pin increases power supply rejection, and affects turn-on time. This pin can be
left open it the capacitor at FC1 is sufficient.
FC1 3
Analog ground for the amplifiers. A 1.0
F capacitor at this pin(with a 5.0F 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
4
Amplifier input. The input capacitor and resistor set low frequency rolloff and input impedance. The
feedback resistor is connected to this pin and Vo1.
Vo1 5
Amplifier Output #1. The dc level is
(Vcc-0.7)/2
Vcc
6
DC supply voltage (+2.0V to +16V) is applied to this pin.
GND
7
Ground pin for the entire circuit.
Vo2 8
Amplifier Output #2. This signal is equal in amplitude, but 180
out-of-phase with that at Vo1.
The dc level is
(Vcc-0.7V)/2
Function Typical
Change
Units
Input Bias Current(@Vin)
40
A/
C
Total Harmonic Distortion
(Vcc=6.0V, R
L
=32 Pout=125mW, f=1KHz)
+0.003
%/
C
Power Supply Current
(Vcc=3.0V, R
L
=
,CD=0V)
(Vcc=3.0V, R
L
=
,CD=2.0V)
-2.5
-0.03
A/
C
GENERAL
The PJ34119 is a low power audio amplifier capable of low voltage operation (Vcc=2.0V 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
80dB(at f100Hz), and the closed loop gain is set by external resistor Rf and Rj. The amplifier is unity gain
stable, and has a unity gain frequency of approximately 1.5MHz. In order to adequately cover the telephone voice band (300Hz to
3400Hz), a maximum closed loop gain of 46 is recommended. Amplifier #2 is internally set to gain of 1.0(0dB).
The outputs of both amplifiers are capable of souring and sinking a peak current of 200mA.The outputs can typically swing to
within
0.4V above ground, and to within1.3V below Vcc, at the maximum current. See Figure 18 and 19 for V
OH
and V
OL
curves.
The output dc offset voltage (Vo1-Vo2) is primarily a function of the feedback resistor (R
f
), and secondarily due to the
amplifiers' input offset voltages. The input offset voltage of the two amplifiers will 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 Vin (pin 4) and through R
f
,
forcing Vo1 to shift negative by an amount equal to [R
f
I
IB
] Vo2 is shifted posited an equal amount. The output offset voltage,
specified in the Electrical Characteristics is measured with the feedback the feedback resistor shown in the Typical Application
Circuit, and therefore takes into account the bias current as wells internal offset voltages of the amplifiers. The bias current is
constant with respect to Vcc.
PIN FUNCTION DESCRIPTION
TYPICAL TEMPERATURE PERFORMANCE (-20C<T
A
<+70C)
PJ34119
Low Power Audio Ampllfier
4-10
2003/10.ver.A
FC1 AND FC2
Power supply rejection is provided by the capacitors (C1 and C2 in the typical Application Circuit) at FC1 and FC2. C2 is
somewhat dominant at low frequencies, while C1 is dominant at high frequencies , as shown in the graphs of Figure 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 function of the
capacitors , and the equivalent impedance looking into FC1 and FC2 (listed in the Electrical Characteristics as R
FC1
and R
FC2
).
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 up through the internal 50K and 125 K
resistors. The graph of Figure 1 indicates the turn-on time upon application
of Vcc of +6.0V. The turn-on time is
60% longer for Vcc=3.0V, and 20% less for Vcc=9.0V. Turn-off time is <10s upon
removal of Vcc.
CHIP DISABLE
The chip Disable (Pin 1) can be used to power down the IC to conserve power, or for muting, or both. When at a Logic "0" (0V
to 0.8V), the PJ34119 is enabled for normal operation. When Pin 1 is a Logic"1"(2.0V to Vcc V ), the IC is disabled. If Pin 1 is
open, that is equivalent to Logic "0" although good design proactive dictates that an input should never be left open. Input
impedance at Pin 1 is a nominal 90 K
. The power supply current (when disabled) is shown in Figure 15.
Muting, defined as the change in differential gain from normal operation to muted operation, is in excess of 70dB.The turn-off
time the audio output, from the application of the CD signal, is <2.0
s, and turn on-time is 12 ms-15ms. Both times are
independent of C1,C2, and Vcc.
When the PJ34119 is disabled, the voltage at FC1 and FC2 do not change as they are powered from Vcc. The outputs, Vo1 and
Vo2, change to high impedance condition, removing the signal from the speaker. If signals from other sources are to be applied to
the outputs (while disabled), they must be within the range of Vcc and Ground.
POWER DISSIPATION
Figure 8 to 10 indicate the device dissipation (within the IC) for various combinations of Vcc, R
L
, and load power. The
maximum power which can safely be dissipated within the PJ34119 is found from the following equation: P
D
=(140
C-T
A
)/
JA
Where T
A
is the ambient temperature; and
JA
is the package thermal resistance (100
C/W for the standard DIP package, and
180
C/W for the surface mount package.) The power dissipated within the PJ34119, in a given application, is found from the
following equation:P
D
=(Vcc
Icc)+(I
RMS
Vcc)-(R
L
I
RMS
2
)
Where Icc is obtained from Figure 15; and I
RMS
is the RMS current at the load; and R
L
is load resistance.Figure 8 to 10, along
with Figure 11 to 13(distortion curves), and a peak working load current of
200mA, define the operating range for the PJ34119.
The operating range is further defined in terms of allowable load power in Figure 14 for loads of 8.0
,16 and 32. The
left(ascending portion of each of the three curves is defined by the power level at which 10% distortion occurs. The center flat
portion of each curve is defined by the maximum output current capability of the PJ34119. The right(descending) portion of each
curve is defined by the maximum internal power dissipation of the IC at 25
C. At higher ambient temperatures, the maximum
load power must be reduced according to the above equations. Operating the device beyond the current and junction temperature
limits will degrade long term reliability.
LAYOUT CONSIDERATIONS
Normally a snubber is not needed at the output of the PJ34119, unlike many other audio amplifiers, However, the PC
board layout, stray capacitances, and the manner in which the speaker wires are configured, may dictate otherwise. Generally, the
speaker wires should be twisted tightly, and not more than afew inches in length
PJ34119
Low Power Audio Ampllfier
5-10
2003/10.ver.A
Figure 1.Turn-On Time versus C1,C2 at Power-On
FIGURE 3.DIFFERENTIAL GAIN
VERSUS FREQUENCY
FIGURE 5.POWER SUPPLY REJECTION versus
FREQUENCY(C2=5.0
F)
FIGURE 2.AMPLIFIER #1
OPEN LOOP GAIN AND PHASE
FIGURE 4.POWER SUPPLY REJECTION versus
FREQUENCY(C2=10
F)
FIGURE 6.Power SUPPLY REJECTION versus
FREQUENCY(C2=1.0
F)
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