GTM CORPORATION
ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
GSCLM 386
L O W V O LT AG E A U D I O P O W E R A M P L I F I E R
Description
The GSCLM386 is a power amplifier, designed for use in low voltage consumer applications. The gain is internally set to 20 to keep
external part count low, but the addition of an external resistor and capacitor between pin 1 and pin 8 will increase the gain to any value up
from 20 to 200.
The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only
24 milliwatts when operating from a 6 voltage supply, making the GSCLM386 ideal for battery operation.
Features
Battery operation
Minimum external parts
Wide supply voltage range: 4V~12V
Low quiescent current drain: 4mA
Voltage gains:20~200
Ground referenced input
Self-centering output quiescent voltage
Low distortion: 0.2% (Av =20, Vs=6V, RL =8 , Po=125mW, f=1 kHz)
Applications
AM-FM radio amplifiers
Portable tape player amplifiers
Intercoms
TV sound systems
Line drivers
Ultrasonic drivers
Small servo drivers
Power converters
Package Dimensions
REF.
A
B
C
D
E
F
Millimeter
Min.
Max.
5.80
4.80
3.80
0°
0.40
0.19
6.20
5.00
4.00
8°
0.90
0.25
REF.
Millimeter
Min.
Max.
M
H
L
J
K
G
0.10
0.25
0.35
0.49
1.35
1.75
0.375 REF.
45°
1.27 TYP.
Equivalent Schematic and Connection Diagram
GSCLM386
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ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
Absolute Maximum Ratings (Note 2)
Parameter
Symbol
VCC
Pd
Vi
Topr
Tstg
Tj
Supply Voltage
Power Dissipation
Input Voltage
Operating Temperature
Storage Temperature
Junction Temperature
Electrical Characteristics
Parameter
Operating Supply Voltage
Quiescent Current
Output Power
Voltage Gain
Bandwidth
Total Harmonic Distortion
Power Supply Rejection
Ration
Input Resistance
Input Bias Current
(TA=25
Value
15
600
-0.4 ~ +0.4
0 ~ 70
-65 ~ 150
150
Unit
V
mW
V
Note1, 2)
Symbol
Test Conditions
VS
IQ
VS=6V, VIN=0
VS=6V, RL=8 , THD=10%
PO
VS=9V, RL=8 , THD=10%
VS=6V, f=1kHz
GV
10 F form Pin1 to Pin8
BW
VS=6V, Pin1 to Pin8 open
PO=125mW, VS=6V, f=1kHz
THD
RL=8 , Pin1 to Pin8 open
VS=6V, f=1kHz, CBYPASS=10 F Pin1
PSRR
and Pin8 open, Referred to output
RIN
IBIAS VS=6V, Pin2 to Pin3 open
Min
4
230
480
Max
12
8
-
Unit
V
mA
-
dB
-
Typ
4
26
46
300
-
kHz
-
0.2
-
%
-
50
-
dB
-
50
250
-
k
nA
-
mW
Note1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note2: 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.
Note3: For operation in ambient temperatures above 25 , the device must be derated based on a 150 maximum junction temperature
and 1) a thermal resistance of 107 /W, junction to ambient for the dual-in-line package and 2)a thermal resistance of 170 /W for
the small outline package.
Application Hints
Gina Control
To make the GSCLM386 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 GSCLM386 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 GSCLM386 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 F capacitor or a short to ground depending on the
dc source resistance on the driven input.
GSCLM386
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ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
Typical Performance Characteristics
GSCLM386
Fig 1. Quiescent Supply Current
vs. Supply Voltage
Fig 2. Power Supply Rejection Ratio
(Referred to the output) vs. Frequency
Fig 3. Peak-to-Peak Voltage Swing
vs. Supply Voltage
Fig 4. Voltage Gain vs. Frequency
Fig 5. Distortion vs. Frequency
Fig 6. Distortion vs. Output Power
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ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
Fig 7. Device Dissipation
vs. Output Power -4
Fig 9. Device Dissipation
vs. Output Power -16
GSCLM386
Load
Load
Fig 8. Device Dissipation
vs. Output Power -8
Load
Fig 10. Frequency Response with
Bass Boost
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ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
Typical Applications
Amplifier with Gain=20
Minimum Parts
Amplifier with Gain=50
Amplifier with Bass Boost
GSCLM386
Amplifier with Gain=200
Low Distortion Power Wienbridge Oscillator
Square Ware Oscillator
Page: 5/6
ISSUED DATE :2005/06/17
REVISED DATE :2005/12/27C
AM Radio Power Amplifier
Note4: Twist supply lead and supply ground very tightly.
Note5: Twist speaker lead and ground very tightly.
Note6: Ferrite bead in Ferroxcube K5-001-001/3B with 3 turns of wire.
Note7: R1C1 band limits input signals.
Note8: All components must be spaced very closely to IC.
Important Notice:
All rights are reserved. Reproduction in whole or in part is prohibited without the prior written approval of GTM.
GTM reserves the right to make changes to its products without notice.
GTM semiconductor products are not warranted to be suitable for use in life-support Applications, or systems.
GTM assumes no liability for any consequence of customer product design, infringement of patents, or application assistance.
Head Office And Factory:
Taiwan: No. 17-1 Tatung Rd. Fu Kou Hsin-Chu Industrial Park, Hsin-Chu, Taiwan, R. O. C.
TEL : 886-3-597-7061 FAX : 886-3-597-9220, 597-0785
China: (201203) No.255, Jang-Jiang Tsai-Lueng RD. , Pu-Dung-Hsin District, Shang-Hai City, China
TEL : 86-21-5895-7671 ~ 4 FAX : 86-21-38950165
GSCLM386
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