LM3875TF/NOPB National Semiconductor, LM3875TF/NOPB Datasheet - Page 6

• Manufacturer Part Number: LM3875TF/NOPB
• Description: IC AMP AUDIO PWR 56W AB TO220-11
• Manufacturer: National Semiconductor
• Series: Overture™r
• Type: Class ABr

Specifications of LM3875TF/NOPB

• Output Type: 1-Channel (Mono)
• Max Output Power X Channels @ Load: 56W x 1 @ 8 Ohm
• Voltage - Supply: 20 V ~ 84 V, ±10 V ~ 42 V
• Features: Short-Circuit and Thermal Protection
• Mounting Type: Through Hole
• Package / Case: TO-220-11 (Bent and Staggered Leads)
• Amplifier Class: AB
• No. Of Channels: 1
• Output Power: 56W
• Supply Voltage Range: 20V To 84V
• Load Impedance: 8ohm
• Operating Temperature Range: -20°C To +85°C
• Amplifier Case Style: TO-220
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM3875TF; *LM3875TF/NOPB; LM3875TF; Q870876

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External Components Description
*Optional components dependent upon specific design requirements. Refer to the Application Information section for more information.
OPTIONAL EXTERNAL COMPONENT INTERACTION
Although the optional external components have specific
desired functions that are designed to reduce the bandwidth
and eliminate unwanted high frequency oscillations they may
cause certain undesirable effects when they interact. Inter-
action may occur for components whose reactances are in
close proximity to one another. One example would be the
coupling capacitor, C
Components
(Figure 1 and Figure 2)
R
R
C
C
R
*C
Ri
*Ci
R
*R
*C
*R
*C
*L
*R
C
IN
A
A
B
f1
S
C
f2
f
SN
SN
Acts as a volume control by setting the voltage level allowed to the amplifier’s input terminals.
Provides DC voltage biasing for the single supply operation and bias current for the positive input terminal.
Provides bias filtering.
Provides AC coupling at the input and output of the amplifier for single supply operation.
Prevents currents from entering the amplifier’s non-inverting input which may be passed through to the load
upon power-down of the system due to the low input impedance of the circuitry when the under-voltage
circuitry is off. This phenomenon occurs when the supply voltages are below 1.5V.
Reduces the gain (bandwidth of the amplifier) at high frequencies to avoid quasi-saturation oscillations of the
output transistor. The capacitor also suppresses external electromagnetic switching noise created from
fluorescent lamps.
Inverting input resistance to provide AC Gain in conjunction with R
Feedback capacitor. Ensures unity gain at DC. Also a low frequency pole (highpass roll-off) at:
Feedback resistance to provide AC Gain in conjunction with Ri.
At higher frequencies feedback resistance works with C
Ri. A high frequency pole (lowpass roll-off) exists at:
Compensation capacitor that works with R
Works with C
Works with R
= 1/(2πR
Provides high impedance at high frequencies so that R may decouple a highly capacitive load and reduce the
Q of the series resonant circuit due to capacitive load. Also provides a low impedance at low frequencies to
short out R and pass audio signals to the load.
Provides power supply filtering and bypassing.
f
f
c
c
C
, and the compensation capacitor, C
= 1/(2π Ri Ci).
= [R
f1
SN
R
C
f2
SN
SN
SN
] (s + 1/R
).
to stabilize the output stage by creating a pole that eliminates high frequency oscillations.
to stabilize the output stage by creating a pole that eliminates high frequency oscillations. f
f2
C
f
]/[(R
f1
+ R
f2
) (s + 1/C
f
.
f1
Functional Description
and R
6
f
These two components act as low impedances to certain
frequencies which will couple signals from the input to the
output. Please take careful note of basic amplifier compo-
nent functionality when designing in these components.
The optional external components shown in Figure 2 and
described above are applicable in both single and split volt-
age supply configurations.
(R
f2
f1
to reduce the AC Gain at higher frequencies.
+R
f
to provide lower AC Gain in conjunction with R
f2
))].
f1
.
f1
and
c