Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range
Ceramic DIP
Molded DIP
Operating Temperature Range
Extended (LM78S40J)
Industrial (LM78S40N)
Commercial (LM78S40CN)
Lead Temperature
Ceramic DIP (Soldering, 60 sec.)
Molded DIP (Soldering, 10 sec.)
Internal Power Dissipation (Note 2) (Note
16L-Ceramic DIP
16L-Molded DIP
Input Voltage from V
IN
to GND
Input Voltage from V
+
(Op Amp)
−65˚C to +175˚C
−65˚C to +150˚C
−55˚C to +125˚C
−40˚C to +125˚C
0˚C to +70˚C
300˚C
265˚C
3)
1.50W
1.04W
40V
to GND
Common Mode Input Range
(Comparator and Op Amp)
Differential Input Voltage
(Note 4)
Output Short Circuit
Duration (Op Amp)
Current from V
REF
Voltage from Switch
Collectors to GND
Voltage from Switch
Emitters to GND
Voltage from Switch
Collectors to Emitter
Voltage from Power Diode to GND
Reverse Power Diode Voltage
Current through Power Switch
Current through Power Diode
ESD Susceptibility
40V
−0.3 to V+
±
30V
Continuous
10 mA
40V
40V
40V
40V
40V
1.5A
1.5A
(to be determined)
LM78S40
Electrical Characteristics
(Note 5)
T
A
= Operating temperature range, V
IN
= 5.0V, V
+
(Op Amp) = 5.0V, unless otherwise specified.
Symbol
I
CC
I
CC
Parameter
Supply Current
(Op Amp Disconnected)
Supply Current
(Op Amp Connected)
REFERENCE SECTION
V
REF
Reference Voltage
I
REF
= 1.0 mA
Extend −55˚C
<
T
A
<
+125˚C,
Comm 0
<
T
A
<
+70˚C,
V
R LINE
V
R LOAD
Reference Voltage
Line Regulation
Reference Voltage
Load Regulation
OSCILLATOR SECTION
I
CHG
I
CHG
I
DISCHG
I
DISCHG
V
OSC
t
on
/t
off
Charging Current
Charging Current
Discharge Current
Discharge Current
Oscillator Voltage Swing
Ratio of Charge/
Discharge Time
CURRENT LIMIT SECTION
V
CLS
Current Limit Sense
Voltage
Output Saturation Voltage 1
Output Saturation Voltage 2
T
A
= 25˚C
250
350
mV
V
IN
= 5.0V, T
A
= 25˚C
V
IN
= 40V, T
A
= 25˚C
V
IN
= 5.0V, T
A
= 25˚C
V
IN
= 40V, T
A
= 25˚C
V
IN
= 5.0V, T
A
= 25˚C
20
20
150
150
0.5
6.0
50
70
250
350
µA
µA
µA
µA
V
µs/µs
Indus −40˚C
<
T
A
<
+85˚C
= 3.0V to V
IN
= 40V,
V
IN
I
REF
= 1.0 mA, T
A
= 25˚C
I
REF
= 1.0 mA to I
REF
= 10 mA,
T
A
= 25˚C
1.180
1.245
0.04
0.2
1.310
0.2
0.5
V
mV/V
mV/mA
V
IN
= 5.0V
V
IN
= 40V
V
IN
= 5.0V
V
IN
= 40V
Conditions
Min
Typ
1.8
2.3
Max
3.5
5.0
4.0
5.5
Units
mA
mA
mA
mA
GENERAL CHARACTERISTICS
OUTPUT SWITCH SECTION
V
SAT 1
V
SAT 2
I
SW
= 1.0A (Figure
1)
I
SW
= 1.0A (Figure
2)
1.1
0.45
1.3
0.7
V
V
3
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