LM3940
Absolute Maximum Ratings
Lead Temperature (Soldering, 5 seconds)
Power Dissipation (Note 2)
Input Supply Voltage
ESD Rating (Note 3)
260˚C
7.5V
2 kV
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range
−65˚C to +150˚C
Internally Limited
Operating Junction Temperature Range −40˚C to +125˚C
Electrical Characteristics
Limits in standard typeface are for T
J
= 25˚C, and limits in
boldface type
apply over the full operating temperature range. Un-
less otherwise specified: V
IN
= 5V, I
L
= 1A, C
OUT
= 33 µF.
Symbol
V
O
Parameter
Output Voltage
Line Regulation
Conditions
5 mA
≤
I
L
≤
1A
I
L
= 5 mA
4.5V
≤
V
O
≤
5.5V
Load Regulation
50 mA
≤
I
L
≤
1A
35
50
80
Z
O
Output Impedance
I
L
(DC) = 100 mA
I
L
(AC) = 20 mA (rms)
f = 120 Hz
I
Q
Quiescent Current
4.5V
≤
V
IN
≤
5.5V
I
L
= 5 mA
V
IN
= 5V
I
L
= 1A
e
n
V
O
− V
IN
Output Noise Voltage
Dropout Voltage
I
L
= 100 mA
I
L
(SC)
Short Circuit Current
R
L
= 0
110
1.7
1.2
BW = 10 Hz–100 kHz
I
L
= 5 mA
I
L
= 1A
0.5
0.8
1.0
150
200
A
mV
V
150
110
10
15
20
200
250
µV (rms)
mA
35
mΩ
Typical
3.3
20
LM3940
min
3.20
3.13
max
3.40
3.47
40
mV
V
Units
Thermal Performance
Thermal Resistance
Junction-to-Case
Thermal Resistance
Junction-to-Ambient
3-Lead TO-220
3-Lead TO-263
3-Lead TO-220
3-Lead TO-263
8-Lead LLP (Note 2)
4
4
60
80
35
˚C/W
˚C/W
˚C/W
˚C/W
˚C/W
Note 1:
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of its rated operating conditions.
Note 2:
The maximum allowable power dissipation is a function of the maximum junction temperature, T
J
, the junction-to-ambient thermal resistance,
θ
JA
, and the
ambient temperature, T
A
. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown.
The value of
θ
JA
(for devices in still air with no heatsink) is 60˚C/W for the TO-220 package, 80˚C/W for the TO-263 package, and 174˚C/W for the SOT-223 package.
The effective value of
θ
JA
can be reduced by using a heatsink (see Application Hints for specific information on heatsinking). The value of
θ
JA
for the LLP package
is specifically dependant on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for
the LLP package, refer to Application Note AN-1187. It is recommended that 6 vias be placed under the center pad to improve thermal performance.
Note 3:
ESD rating is based on the human body model: 100 pF discharged through 1.5 kΩ.
Note 4:
All limits guaranteed for T
J
= 25˚C are 100% tested and are used to calculate Outgoing Quality Levels. All limits at temperature extremes are guaranteed
via correlation using standard Statistical Quality Control (SQC) methods.
Note 5:
Dropout voltage is defined as the input-output differential voltage where the regulator output drops to a value that is 100 mV below the value that is
measured at V
IN
= 5V.
3
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