Elektronische Bauelemente

SGPLM386

Low Voltage Audio Power Amplifier

17-Dec-2009 Rev. A

Page 2 of 6

ELECTRICAL CHARACTERISTICS

1, 2

CHARACTERISTICS

SYMBOL

MIN

TYP

MAX

UNITS

TEST CONDITIONS

Operating Supply Voltage

4

-

12

V

Quiescent Current

-

4

8

mA

230

-

-

Output Power

480

-

-

mW

-

26

-

Voltage Gain

-

46

-

dB

10

µF from Pin1 to Pin8

Bandwidth

BW

-

300

-

kHz

Total Harmonic Distortion

THD

-

0.2

-

%

Power Supply Rejection Ration

PSRR

-

50

-

dB

µF

Pin1 to Pin8 open, Referred to output

Input Resistance

-

50

-

K

Input Bias Current

-

250

-

nA

Note:

1.

All voltages are measured with respect to the ground pin, unless otherwise specified.

2.

Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which

the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications

under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings.

Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device

performance.

3.

For operation in ambient temperatures above 25°C , the device must be derated based on a 150°C maxim um junction temperature and 1) a

thermal resistance of 107°C /W, junction to ambient for the dual-in-line package and 2)a thermal resistance of 170°C /W for the small outline

package.

APPLICATION HINTS

GAIN CONTROL

To make the SGPLM386 a more versatile amplifier, two pins (1 and 8) are provided for gain control. With pins 1 and

8 open the 1.35K

resistor sets the gain at 20 (26dB),If a capacitor is put from pin 1 to 8,bypassing the 1.35k

resistor,

the gain will go up to 200 (46dB). If a resistor is placed in series with the capacitor the gain can be set to any value from

20 to 200.Gain control can also be done by capacitively coupling a resistor (or FET) prom pin 1 to ground.

Additional external components can be placed in parallel with the internal feedback resistors to tailor the gain and

frequency response for individual applications. For example we can compensate poor speaker bass response by

frequency shaping the feedback path. This is done with a series RC from pin 1 to 5 (paralleling the internal 15k

resistor). For 6 dB effective bass boost: R=15k , the lowest value for good stable operation in R=10k, if pin 8 is open, If

pins 1 and 8 are bypassed then R as low as 2k

can be used. This restriction is because the amplifier is only

compensated for closed-loop gains greater than 9.

INPUT BIASING

The schematic show that both input are biased to ground with a 50k

resistor. The base current of the input

transistors is about 250nA, so the inputs are at about 12.5mW when left open. If the dc source resistance driving the

SGPLM386 is higher than 250k

it will contribute very little additional offset (about 2.5mW at the input, 50mW at the

output). If the dc source resistance is less than 10k, then shorting the unused input to ground will keep the offset low

(about 2.5mW at the input, 50mW at the output). For dc source resistance between these values we can eliminate

excess offset by putting a resistor from the unused input to ground, equal in value to the dc source resistance. Of course

all offset problems are eliminated if the input is capacitively coupled.

When using the SGPLM386 with higher gains (bypassing the 1.35k

resistor between pin1 and 8) it is necessary to

bypass the unused input, preventing degradation of gain and possible instabilities. This is done with a 0.1

µF capacitor or

a short to ground depending on the dc source resistance on the driven input.