LM3940
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SNVS114E –MAY 1999–REVISED MARCH 2013
ELECTRICAL CHARACTERISTICS
Limits in standard typeface are for TJ = 25°C, and limits in boldface type apply over the full operating temperature range.
Unless otherwise specified: VIN = 5V, IL = 1A, COUT = 33 μF.
(1)
Symbol
Parameter
Conditions
Typical
LM3940
min
Units
max
3.20
3.13
3.40
3.47
VO
Output Voltage
5 mA ≤ IL ≤ 1A
3.3
20
V
IL = 5 mA
4.5V ≤ VIN ≤ 5.5V
Line Regulation
Load Regulation
40
(1)
(2)
mV
50
80
50 mA ≤ IL ≤ 1A
35
35
IL (DC) = 100 mA
IL (AC) = 20 mA (rms)
f = 120 Hz
ZO
Output Impedance
mΩ
4.5V ≤ VIN ≤ 5.5V
IL = 5 mA
15
20
10
IQ
Quiescent Current
mA
VIN = 5V
IL = 1A
200
250
110
150
0.5
BW = 10 Hz–100 kHz
IL = 5 mA
en
Output Noise Voltage
μV (rms)
0.8
1.0
IL = 1A
V
Dropout Voltage
VDO
(2)
150
200
IL = 100 mA
RL = 0
110
1.7
mV
A
IL(SC)
Short Circuit Current
1.2
(1) All limits specified for TJ = 25°C are 100% tested and are used to calculate Outgoing Quality Levels. All limits at temperature extremes
are verified via correlation using standard Statistical Quality Control (SQC) methods.
(2) 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 VIN = 5V.
THERMAL PERFORMANCE
3-Lead TO-220
4
4
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
Thermal Resistance, Junction-to-Case, θJC
3-Lead DDPAK/TO-263
8-Lead WSON
6
3-Lead TO-220
60
80
35
Thermal Resistance, Junction-to-Ambient, θJA
3-Lead DDPAK/TO-263
(1)
8-Lead WSON
(1) The maximum allowable power dissipation is a function of the maximum junction temperature, TJ, the junction-to-ambient thermal
resistance, θJA, and the ambient temperature, TA. Exceeding the maximum allowable power dissipation will cause excessive die
temperature, and the regulator will go into thermal shutdown. The value of θJA (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 θJA can be
reduced by using a heatsink (see APPLICATION HINTS for specific information on heatsinking). The value of θJA for the WSON
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 WSON package, refer to Application Note AN-1187 SNOA401. The θJA rating for the WSON is
with a JESD51-7 test board having 6 thermal vias under the exposed pad.
Copyright © 1999–2013, Texas Instruments Incorporated
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