LM388 National Semiconductor, LM388 Datasheet - Page 3

• Manufacturer Part Number: LM388
• Description: LM388 1.5W Audio Power Amplifier
• Manufacturer: National Semiconductor

Typical Performance Characteristics
Application Hints
GAIN CONTROL
To make the LM388 a more versatile amplifier two pins (2
and 6) are provided for gain control With pins 2 and 6 open
the 1 35 k
tor is put from pins 2 to 6 bypassing the 1 35 k
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 A low frequency pole in the gain response is
caused by the capacitor working against the external resis-
tor in series with the 150
is eliminated and a resistor connects pins 2 to 6 then the
Peak-to-Peak Output Voltage
Swing vs Supply Voltage
Distortion vs Output Power
resistor sets the gain at 20 (26 dB) If a capaci-
internal resistor If the capacitor
resistor
Device Dissipation vs Output
Power 4
Device Dissipation vs
Output Power 16
Voltage Gain vs Frequency
(Continued)
3
Load
output dc level may shift due to the additional dc gain Gain
control can also be done by capacitively coupling a resistor
(or FET) from pin 6 to ground as in Figure 7
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 fre-
quency shaping the feedback path This is done with a se-
ries RC from pin 6 to 13 (paralleling the internal 15 k
tor) For 6 dB effective bass boost R j 15 k
value for good stable operation is R
Load
Distortion vs Frequency
Device Dissipation vs
Output Power 8
e
10 k
Load
the lowest
TL H 7846– 6
if pin 2
resis-