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LM386-1 参数 Datasheet PDF下载

LM386-1图片预览
型号: LM386-1
PDF下载: 下载PDF文件 查看货源
内容描述: 低电压阿迪奥功率放大器 [Low Voltage Adio Power Amplifier]
分类和应用: 放大器功率放大器
文件页数/大小: 8 页 / 369 K
品牌: Wing Shing [ WING SHING COMPUTER COMPONENTS ]
 浏览型号LM386-1的Datasheet PDF文件第1页浏览型号LM386-1的Datasheet PDF文件第2页浏览型号LM386-1的Datasheet PDF文件第4页浏览型号LM386-1的Datasheet PDF文件第5页浏览型号LM386-1的Datasheet PDF文件第6页浏览型号LM386-1的Datasheet PDF文件第7页浏览型号LM386-1的Datasheet PDF文件第8页  
LM386-1  
Application Hints  
GAIN CONTROL  
INPUT BIASING  
a more versatile amplifier, two pins (1  
The schematic shows that both inputs are biased to ground  
with a 50 kresistor. The base current of the input transis-  
tors is about 250 nA, so the inputs are at about 12.5 mV  
when left open. If the dc source resistance driving the LM386  
is higher than 250 kit will contribute very little additional  
offset (about 2.5 mV at the input, 50 mV at the output). If the  
dc source resistance is less than 10 k, then shorting the  
unused input to ground will keep the offset low (about 2.5 mV  
at the input, 50 mV at the output). For dc source resistances  
between these values we can eliminate excess offset by put-  
ting a resistor from the unused input to ground, equal in  
value to the dc source resistance. Of course all offset prob-  
lems are eliminated if the input is capacitively coupled.  
To make LM386-1  
and 8) are provided for gain control. With pins 1 and 8 open  
the 1.35 kresistor sets the gain at 20 (26 dB). If a capacitor  
is put from pin 1 to 8, bypassing the 1.35 kresistor, the  
gain will go up to 200 (46 dB). 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 cou-  
pling a resistor (or FET) from pin 1 to ground.  
Additional external components can be placed in parallel  
with the internal feedback resistors to tailor the gain and fre-  
quency response for individual applications. For example,  
we can compensate poor speaker bass response by fre-  
quency shaping the feedback path. This is done with a series  
RC from pin 1 to 5 (paralleling the internal 15 kresistor).  
For 6 dB effective bass boost: R . 15 k, the lowest value  
for good stable operation is R = 10 kif pin 8 is open. If pins  
1 and 8 are bypassed then R as low as 2 kcan be used.  
This restriction is because the amplifier is only compensated  
for closed-loop gains greater than 9.  
with higher gains (bypassing the  
When using LM386-1  
1.35 kresistor between pins 1 and 8) it is necessary to by-  
pass 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.  
Pad Location  
8
7
6
90  
1
90  
5
2
3
4B  
4A  
Y
X
0
Chip size 1.4 x 1.6 mm  
Pad Location Coordinates  
Coordinates  
Pad N  
Pad Name  
X
Y
1
2
3
4A  
4B  
5
6
7
8
Gain  
-input  
+input  
GND  
GND  
VOUT  
VCC  
BYPASS  
Gain  
120  
120  
120  
550  
600  
600  
750  
440  
120  
975  
665  
100  
100  
390  
1015  
1405  
1405  
1405  
8-3  
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