LM391N-100 National Semiconductor, LM391N-100 Datasheet - Page 6

• Manufacturer Part Number: LM391N-100
• Description: IC AMP AUDIO PWR MONO AB 16DIP
• Manufacturer: National Semiconductor
• Type: Class ABr

Specifications of LM391N-100

• Output Type: 1-Channel (Mono)
• Features: Shutdown, Thermal Protection
• Mounting Type: Through Hole
• Package / Case: 16-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Voltage - Supply: -
• Max Output Power X Channels @ Load: -
• Other names: *LM391N-100; LM391N100

Application Hints
PROTECTION CIRCUITRY
The protection circuits of the LM391 are very flexible and
should be tailored to the output transistor’s safe operating
area The protection V-I characteristics circuitry and resis-
tor formulas are described below The diodes from the out-
put to each supply prevent the output voltage from exceed-
ing the supplies and harming the output transistors The out-
put will do this if the protection circuitry is activated while
driving an inductive load
TURN-ON DELAY
It is often desirable to delay the turn-ON of the power ampli-
fier This is easily implemented by putting a resistor in series
with a capacitor from pin 14 to ground The value of the
Note
transistors
Type of Protection
Current Limit
Single Slope SOA
Protection
Dual Slope SOA
Protection
(V
B
e
Protection Circuitry with External Components
is the current limit V
V
a
)
BE
voltage 650 mV Assumptions V
(Continued)
R
R
R
R
E
E
E
E
e
e
e
Protection Circuit Resistor Formulas (V
R
I
I
I
L
L
L
TL H 7146– 5
a
ll
R
R
1
1
V
e
e
Not Required
M ll
R
R
6
R
2
2
1
R
resistor is set to limit the current to less than 1 mA (the
absolute maximum) This resistor with the capacitor gives a
time constant of RC The turn-ON delay is approximately 2
time constants
Example
So
R
a 30V rating
V
V
V
M
M
1
Amplifier with maximum supply of 30V like the 20W 8
example in the data sheet requiring a delay of 1 second
Time delay
e
a
b
b
is the load supply voltage V
30k Solving for C gives 16 7 F Use C
B
e
e
Protection Characteristics
2 RC
R
V
Short
1 k
1 k
2
a
R
)
R
2
e
M
Max V
is the maximum rated V
1 mA
R
3
a
e
R
Not Required
Not Required
2
R
I
3
L
e
R
R
V
E
CE
a
20 F with
3
b
TL H 7146 – 6
of the output
b
1