Datasheet

LM2940-N, LM2940C
www.ti.com 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
) 12V 15V
Parameter Conditions Typ LM2940-N LM2940- Typ LM2940-N LM2940-
Units
Limit
(1)
N/833 Limit
(1)
N/833
Limit
(2)
Limit
(2)
Ripple Rejection f
O
= 120 Hz, 1 V
rms
,
I
O
= 100 mA
LM2940-N 66 54/48 dB
MIN
LM2940C 66 54 64 52
f
O
= 1 kHz, 1 V
rms
, dB
MIN
52/46 48/42
I
O
= 5 mA
Long Term Stability mV/
48 60
1000 Hr
Dropout Voltage I
O
= 1A 0.5 0.8/1.0 0.7/1.0 0.5 0.8/1.0 0.7/1.0 V
MAX
I
O
= 100 mA 110 150/200 150/200 110 150/200 150/200 mV
MAX
Short Circuit Current See
(3)
1.9 1.6 1.6/1.3 1.9 1.6 1.6/1.3 A
MIN
Maximum Line R
O
= 100Ω
Transient
LM2940-N, T ≤ 100 ms 75 60/60
LM2940-N/883, T ≤ 20 ms 40/40 40/40 V
MIN
LM2940C, T ≤ 1 ms 55 45 55 45
Reverse Polarity R
O
= 100Ω
DC Input Voltage
LM2940-N, LM2940-N/883 −30 −15/−15 −15/−15 −15/−15 V
MIN
LM2940C −30 −15 −30 −15
Reverse Polarity R
O
= 100Ω
Transient Input
LM2940-N, T ≤ 100 ms −75 −50/−50
Voltage
LM2940-N/883, T ≤ 20 ms −45/−45 −45/−45 V
MIN
LM2940C, T ≤ 1 ms −55 −45/−45 −55 −45/−45
(3) Output current will decrease with increasing temperature but will not drop below 1A at the maximum specified temperature.
Thermal Performance
3-Lead TO-220 4
Thermal Resistance
°C/W
Junction-to-Case, θ
(JC)
3-Lead DDPAK/TO-263 4
3-Lead TO-220
(1)
60
3-Lead DDPAK/TO-263
(1)
80
Thermal Resistance
°C/W
Junction-to-Ambient, θ
(JA)
SOT-223
(1)
174
8-Lead WSON
(1)
35
(1) 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 Application Hints 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.
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