LM391 National Semiconductor Corporation, LM391 Datasheet - Page 4

• Manufacturer Part Number: LM391
• Description: Audio Power Driver (discontinued)
• Manufacturer: National Semiconductor Corporation

Component
C
R
R
R
C
C
R
R
C
C
R
R
C
R
R
C
X
External Components
IN
f
C
AB
R
O
2
L
IN
f 2
f 1
A
B
eb
O
E
TH
C
2
1 F
100k
100k
5 1k
10 F
5 pF
3 9k
10k
0 1 F
5 pF
100
2 7
0 1 F
0 3
39k
1000 pF
10
Typical Value
ll
5 H
Input coupling capacitor sets a low frequency pole with R
f
Sets input impedance and DC bias to input
Feedback resistor for minimum offset voltage at the output this should be equal to R
Feedback resistor that works with R
A
Feedback capacitor This reduces the gain to unity at DC for minimum offset voltage at the
output Also sets a low frequency pole with R
f
Compensation capacitor Sets gain bandwidth product and a high frequency pole
GBW
Max f
AB bias resistor
AB bias potentiometer Adjust to set bias current in the output stage
Bypass capacitor for bias This improves high frequency distortion and transient response
Ripple capacitor This improves negative supply rejection at midband and high frequencies
C
Bleed resistor This removes stored charge in output transistors
Output compensation resistor This resistor and C
will vary slightly for different output devices
Output compensation capacitor This works with R
output power transistors
Emitter degeneration resistor This resistor gives thermal stability to the output stage
quiescent current IRC PW5 type
Shutdown resistor Sets the amount of current pulled out of pin 14 during shutdown
Compensation capacitors for protection circuitry
Used to isolate capacitive loads usually 20 turns of wire wrapped around a 10
L
L
(Figure 1)
V
R
e
e
e
if used must equal C
2 R
2 R
h
e
1
for stable design
a
1
2 5000C
1
IN
f 1
R
R
C
C
f 2
f 1
f
IN
1
C
f
h
e
C
GBW
4
500 kHz
A
V
f 2
to set the voltage gain
Comments
f 1
O
O
compensate the output stage This value
to form a zero that cancels f of the
IN
2W resistor
IN