MC34119.PDF

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The MC34119 is a low power audio amplifier intergrated circuit intended

(primarily) for telephone applications, such as in speakerphones. It provides

differential speaker outputs to maximize output swing at low supply voltages

(2.0 V minimum). Coupling capacitors to the speaker are not required. Open

loop gain is 80 dB, 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 MC34119 is available in standard 8–pin DIP, SOIC package, and

TSSOP package.

•

LOW POWER

AUDIO AMPLIFIER

Wide Operating Supply Voltage Range (2.0 V to 16 V), Allows

Telephone

Line Powered Applications

SEMICONDUCTOR

TECHNICAL DATA

•

Low Quiescent Supply Current (2.7 mA Typ) for Battery

Powered Applications

•

Chip Disable Input to Power Down the IC

•

Low Power–Down Quiescent Current (65

A Typ)

•

Drives a Wide Range of Speaker Loads (8.0

and Up)

P SUFFIX

PLASTIC PACKAGE

CASE 626

•

Output Power Exceeds 250 mW with 32 W Speaker

•

Low Total Harmonic Distortion (0.5% Typ)

•

Gain Adjustable from <0 dB to >46 dB for Voice Band

•

Requires Few External Components

MAXIMUM RATINGS

Rating

Value

Unit

D SUFFIX

PLASTIC PACKAGE

CASE 751

(SO–8)

Supply Voltage

–1.0 to +18

Vdc

Maximum Output Current at V O1 , V O2

± 250

Maximum Voltage @ V in , FC1, FC2, CD

Applied Output Voltage to V O1 , V O2 when disabled

–1.0, V CC + 1.0

Vdc

DTB SUFFIX

PLASTIC PACKAGE

CASE 948J

(TSSOP)

Junction Temperature

–55, +140

NOTE: ESD data available upon request.

Block Diagram and Simplified Application

PIN CONNECTIONS

7 5 k

V O2

6 V CC

FC2

Gnd

C i

0.1

R i

3 .0 k V in 4

FC1 3

FC1

V CC

Audio

Input

–

+ #1

5 V O1

Speaker

V in

V O1

4.0 k 4 .0 k

(Top View)

1.0

C2*

5. 0 m F

50 k

1 25 k

–

+ #2

8 V O2

ORDERING INFORMATION

FC2

50 k

Bias

Circuit

1 CD

Chip

Disable

Operating

Temperature Range Package

Device

MC34119

MC34119P

MC34119D

Plastic DIP

SO–8

* = Optional

Differential Gian = 2 x

Gnd

T A = –20 ° to +70 ° C

R f

R i

This device contains 45 active transistors.

MC34119DTB

TSSOP

W Motorola, Inc. 1996

Rev 1

MOTOROLA ANALOG IC DEVICE DATA

MC34119

RECOMMENDED OPERATING CONDITIONS

Characteristics

Symbol

Min

Max

Unit

Supply Voltage

V CC

+2.0

+16

Vdc

Voltage @ CD (Pin 1)

V CD

V CC

Vdc

Load Impedance

R L

8.0

–

Peak Load Current

I L

–

± 200

Differential Gain (5.0 kHz Bandwidth)

AVD

Ambient Temperature

T A

–20

+70

° C

ELECTRICAL CHARACTERISTICS (T A = 25 ° C, unless otherwise noted.)

Characteristics

Symbol

Min

Typ

Max

Unit

AMPLIFIERS (AC CHARACTERISTICS)

AC Input Resistance (@ V In )

r i

–

>30

–

M W

Open Loop Gain (Amplifier #1, f < 100 Hz)

A VOL1

–

Closed Loop Gain (Amplifier #2, V CC = 6.0 V, f = 1.0 kHz, R L = 32

)

A V2

–0.35

+0.35

Gain Bandwidth Product

GBW

–

1.5

–

MHz

Output Power;

V CC = 3.0 V, R L = 16 W , THD 3 10%

P Out3

–

V CC = 6.0 V, R L = 32

THD

10%

P Out6

250

–

V CC = 12 V, R L = 100 W, THD 3 10%

P Out12

400

–

Total Harmonic Distortion (f = 1.0 kHz)

THD

(V CC = 6.0 V, R L = 32 W , P out = 125 mW)

–

0.5

1.0

(V CC

3.0 V, R L = 8.0

, P out = 20 mW)

–

0.5

–

(V CC . 12 V, R L = 32 W , P out = 200 mW)

–

0.6

–

Power Supply Rejection (V CC = 6.0 V, D V CC = 3.0 V)

PSRR

(C1 =

, C2 = 0.01

–

(C1 = 0.1 m F, C2 = 0, f = 1.0 kHz)

–

(C1 = 1.0

F, C2 = 5.0

F, f = 1.0 kHz)

–

Differential Muting (V CC = 6.0 V, 1.0 kHz 3 f 3 20 kHz, CD = 2.0 V)

GMT

–

>70

–

AMPLIFIERS (DC CHARACTERISTICS)

Output DC Level @ V O1 , V O2 , V CC = 3.0 V, R L = 16 (R f = 75 k)

V O(3)

1.0

1.15

1.25

Vdc

V CC = 6.0 V

V O(6)

–

2.65

–

V CC = 12 V

V O(12)

–

5.65

–

Output Level

Vdc

High (I out = –75 mA, 2.0 V 3 V CC 3 16 V)

V OH

–

V CC – 1.0

–

Low (I out = 75 mA, 2.0 V 3 V CC 3 16 V)

V OL

–

0.16

–

Output DC Offset Voltage (V O1 –V O2 )

V O

(V CC = 6.0 V, R f = 75 k W , R L = 32 W )

–30

+30

Input Bias Current @ V in (V CC = 6.0 V)

I IB

–

–100

–200

Equivalent Resistance

k W

@ FC1 (V CC = 6.0 V)

R FC1

100

150

220

@ FC2 (V CC = 6.0 V)

R FC2

CHIP DISABLE (Pin 1)

Input Voltage

Vdc

Low

V IL

–

0.8

High

V IH

2.0

–

Input Resistance (V CC = V CD = 16 V)

R CD

175

POWER SUPPLY

Power Supply Current

(V CC = 3.0 V, R L = 8 , CD = 0.8 V)

I CC3

–

2.7

4.0

(V CC = 16 V, R L =

, CD = 0.8 V)

I CC16

–

3.3

5.0

(V CC = 3.0 V, R L = 8 , CD = 2.0 V)

I CCD

–

100

m A

NOTE: Currents into a pin are positive, currents out of a pin are negative.

MOTOROLA ANALOG IC DEVICE DATA

MC34119

PIN FUNCTION DESCRIPTION

Symbol

Description

Chip Disable – Digital input. A Logic “0” (<0.8 V) sets normal operation. A logic “1” ( . 2.0 V) sets the power down

mode. Input impedance is nominally 90 k

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

F capacitor at Pin 2) provides

(typically) 52 dB 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.

F capacitor at this pin (with a 5.0

V in

Amplifier input. The input capacitor and resistor set low frequency rolloff and input impedance. The feedback

resistor is connected to this pin and V O1 .

V O1

Amplifier Output #1. The dc level is 9 (V CC – 0.7 V)/2.

V CC

DC supply voltage (+2.0 V to +16 V) is applied to this pin.

GND

Ground pin for the entire circuit.

V O2

Amplifier Output #2. This signal is equal in amplitude, but 180 ° out–of–phase with that at V O1 .

The dc level is 9 (V CC – 0.7 V)/2.

TYPICAL TEMPERATURE PERFORMANCE (–20 ° C < T A < +70 ° C)

Function

Typical Change

Units

Input Bias Current (@ V in )

pA/

Total Harmonic Distortion

+0.003

%/ ° C

(V CC = 6.0 V, R L = 32

. P out = 125 mW, f = 1.0 kHz)

Power Supply Current

m A/ ° C

(V CC = 3.0 V, R L =

, CD = 0 V)

–2.5

(V CC = 3.0 V, R L = 8 , CD = 2.0 V)

–0.03

MOTOROLA ANALOG IC DEVICE DATA

Analog ground for the amplifiers. A 1.0

MC34119

DESIGN GUIDELINES

General

The MC34119 is a low power audio amplifier capable of

low voltage operation (V CC = 2.0 V minimum) such as that

encountered in line–powered speakerphones. The circuit

provides a differential output (V O1 –V O2 ) 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.

Figure 1. Turn–On Time versus C1, C2 at Power–On

360

300

240

C1 = 5.0 m F

180

120

C1 = 1.0 m F

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 3 100 Hz), and the

closed loop gain is set by external resistor R f and R i . 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 (0 dB).

The outputs of both amplifiers are capable of sourcing and

sinking a peak current of 200 mA. The outputs can typically

swing to within 9 0.4 V above ground, and to within 9 1.3 V

below V CC , at the maximum current. See Figures 18 and 19

for V OH and V OL curves.

The output dc offset voltage (V O1 –V O2 ) 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 V in (Pin 4)

and through R f , forcing V O1 to shift negative by an amount

equal to [R f × I IB ]. V O2 is shifted positive an equal amount.

The output offset voltage, specified in the Electrical

Characteristics, is 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 CC .

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

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 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 50 k and

125 k W resistors. The graph of Figure 1 indicates the

turn–on time upon application of V CC of +6.0 V. The turn–on

time is 9 60% longer for V CC = 3.0 V, and 9 20% less for

V CC = 9.0 V. Turn–off time is <10 m s upon removal of V CC .

V CC switching from

0 V to 6.0 V

2.0

4.0

6.0

8.0

C2, CAPACITANCE (

. 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 70 dB.

The turn–off time of the audio output, from the application of

the CD signal, is <2.0 m s, and turn on–time is 12 ms–15 ms.

Both times are independent of C1, C2, and V CC .

When the MC34119 is disabled, the voltages at FC1 and

FC2 do not change as they are powered from V CC . The

outputs, V O1 and V O2 , change to a 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 V CC and Ground.

Power Dissipation

Figures 8 to 10 indicate the device dissipation (within the

IC) for various combinations of V CC , R L , and load power. The

maximum power which can safely be dissipated within the

MC34119 is found from the following equation:

P D = (140

C – T A )/

q JA

where T A is the ambient temperature; and q JA is the package

thermal resistance (100

C/W for the standard DIP package,

C/W for the surface mount package.)

The power dissipated within the MC34119, in a given

application, is found from the following equation:

P D = (V CC x I CC ) + (I RMS x V CC ) – (R L x I RMS 2 )

where I CC is obtained from Figure 15; and I RMS is the RMS

current at the load; and R L is the load resistance.

Figures 8 to 10, along with Figures 11 to 13 (distortion

curves), and a peak working load current of ± 200 mA, define

the operating range for the MC34119. 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

MOTOROLA ANALOG IC DEVICE DATA

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” (0 V to 0.8 V), the MC34119 is enabled for normal

operation. When Pin 1 is at a Logic “1” (2.0 V to V CC V), the

IC is disabled. If Pin 1 is open, that is equivalent to a Logic

“0,” although good design practice dictates that an input

should never be left open. Input impedance at Pin 1 is a

nominal 90 k

and 180

MC34119

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 MC34119. The right (descending) portion of each curve is

defined by the maximum internal power dissipation of the IC

at 25

Layout Considerations

Normally a snubber is not needed at the output of the

MC34119, 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 a few inches in length.

Figure 2. Amplifier #1 Open Loop Gain and Phase

Figure 3. Differential Gain versus Frequency

100

108

144

180

R f = 150 k, R i = 6.0 k

Phase

R f = 75 k, R i = 3.0 k

Gain

R f

0 . 1

Input

–

+ #1

V O1

V O2

R i

V O

100

1.0 k

10 k

100 k

1.0 M

100

1.0 k

10 k 20 k

f, FREQUENCY (Hz)

MOTOROLA ANALOG IC DEVICE DATA

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.

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