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SL34119

Low Power Audio Amplifier

System Logic Semiconductor 

SL34119

line powered speakerphone, for example, will require

more filtering than a circuit powered by a well

requlated 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 RFC1 and RFC2).

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 change up through the

internal 50 KΩ and 125 KΩ resistors.

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 to 0.8 Volts), the IL34119 is

enabled for normal operation. When Pin 1 is at a

Logic “1” (2.0 to VCC Volts), 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 KΩ. The power supply current (when

disabled) is shown in Figure 1.

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 µs, and turn

on-time is 12-15 ms. Both times are independent of C1,

C2, and VCC.

When the SL34119 is disabled, the voltages at

FC1 and FC2 do not change as they are powered from

VCC. The outputs, VO1 and VO2, 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 VCC and Ground.

POWER DISSIPATION

Figures 2-4 indicate the device dissipation (within

the IC) for various combinations of VCC, RL,

and load power.The maximum power which can safely

be dissipated within the SL34119 is found from the

following equation:

PD = (140°C - TA)/θJA

where TA is the operating temperature;

and θJA 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 SL34119, in a

given application, is found from the following

eguation:

PD = (VCC x ICC) + (IRMS x VCC) - (RL x IRMS2).

where ICC is obtained from Figure 1;

and IRMS is the RMS current at the load;

and RL is the load resistance.

Figures 2-4, along with Figures 5-7 (distortion

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

define the operating range for the IL34119. The

operating range is further defined in terms of

allowable load power in Figure 8 for load of 8.0 Ω,

16 Ω, and 32 Ω. 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 SL34119. The right

(descending) portion of each curve is defined by the

maximum internal power dissipation of the IC at 25°C.

At higher operating 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 SL34119, 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 be not

more than a few inches in length.

MAXIMUM RATINGS*

Symbol

Parameter

Value

Unit

VCC Supply Voltage

IOUT Maximum Output Current at VO1, VO2

1.0 to +18

V

±250

mA

VIN

MaximumInput Voltage(FC1, FC2, CD, VIN)

-1.0 toVCC +1.0

V

VVO Applied Output Voltage to VO1, VO2 when disabled

Tstg Storage Temperature Range

-1.0 toVCC +1.0

V

-65 to +150

°C

* Maximum Ratings are those values beyond which damage to the device may occur.

Functional operation should be restricted to the Recommended Operating Conditions.

SLS

System Logic

Semiconductor

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