SNVS769I – MARCH 2000 – REVISED APRIL 2013
Electrical Characteristics (continued)
V
IN
= V
O
+ 5V, I
O
= 1A, C
O
= 22
μF,
unless otherwise specified.
Boldface limits apply over the entire operating
temperature range of the indicated device.
All other specifications apply for T
A
= T
J
= 25°C.
Output Voltage (V
O
)
Parameter
Conditions
Typ
12V
LM2940-N
Limit
(1)
LM2940-
N/833
Limit
(2)
Typ
15V
LM2940-N
Limit
(1)
LM2940-
N/833
Limit
(2)
Units
Ripple Rejection
f
O
= 120 Hz, 1 V
rms
,
I
O
= 100 mA
LM2940-N
LM2940C
f
O
= 1 kHz, 1 V
rms
,
I
O
= 5 mA
66
66
54/48
54
52/46
48
I
O
= 1A
I
O
= 100 mA
(3)
dB
MIN
64
52
48/42
60
dB
MIN
mV/
1000 Hr
0.8/1.0
150/200
1.6
0.7/1.0
150/200
1.6/1.3
V
MAX
mV
MAX
A
MIN
Long Term Stability
Dropout Voltage
0.5
110
1.9
75
55
−30
−30
−75
−55
0.8/1.0
150/200
1.6
60/60
0.7/1.0
150/200
1.6/1.3
0.5
110
1.9
Short Circuit Current See
Maximum Line
Transient
R
O
= 100Ω
LM2940-N, T
≤
100 ms
LM2940-N/883, T
≤
20 ms
LM2940C, T
≤
1 ms
45
−15/−15
−15
−50/−50
−45/−45
−45/−45
−55
−45/−45
−45/−45
V
MIN
−15/−15
−30
−15
40/40
55
45
−15/−15
V
MIN
40/40
V
MIN
Reverse Polarity
DC Input Voltage
R
O
= 100Ω
LM2940-N, LM2940-N/883
LM2940C
R
O
= 100Ω
LM2940-N, T
≤
100 ms
LM2940-N/883, T
≤
20 ms
LM2940C, T
≤
1 ms
Reverse Polarity
Transient Input
Voltage
(3)
Output current will decrease with increasing temperature but will not drop below 1A at the maximum specified temperature.
Thermal Performance
Thermal Resistance
Junction-to-Case,
θ
(JC)
3-Lead TO-220
3-Lead DDPAK/TO-263
3-Lead TO-220
Thermal Resistance
Junction-to-Ambient,
θ
(JA)
SOT-223
(1)
8-Lead WSON
(1)
(1)
(1)
(1)
4
4
60
80
174
35
°C/W
3-Lead DDPAK/TO-263
°C/W
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 DDPAK/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
for specific information on heatsinking). The value of
θ
JA
for the WSON package is
specifically dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance
and power dissipation for the WSON package, refer to Application Note AN-1187 (SNOA401). It is recommended that 6 vias be placed
under the center pad to improve thermal performance.
Copyright © 2000–2013, Texas Instruments Incorporated
7
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