General description

lm2940 /LM2940C positive voltage regulator characteristics The ability to generate 1A output current with a typical voltage of 0.5 volt 1V The entire temperature range. In addition, the static current has included a reduction circuit to reduce the difference between the ground current output current between about 3V when the input voltage and the output voltage exceed 3V, and the static current with the input and output difference of 5V is only 30 mAh. The higher one is the VIN-VOUT ≤ 3V. It is also designed for vehicle applications. The LM2940/LM2940C and all adjustment circuits are protected and are not affected by the installation of reverse batteries or 2 batteries jump. During the online period, if the input voltage can instantly exceed the specified maximum working voltage, the regulator will automatically turn off to protect the internal circuits and loads. LM2940/LM2940C cannot be damaged by temporary mirrors in the sequence. Familiar regulator characteristics, such as short circuit and hot overload protection.

Features

The typical leakage voltage 0.5 volts@[

The output current exceeds 1A

before assembly adjust the output voltage

Reverse battery protection

Internal short -circuit current limit

Mirror insertion protection

P+product enhancement test

If adjustment is adjusted The device is far from the power filter, and it needs.

*COUT must be at least 22 μF to maintain stability. It may increase without having to maintain adjustment during the transient period. As far as possible to regulatory agencies. The rated value of the capacitor must be within the same working temperature range as the regulator, and ESR must be crucial; see the curve.

Absolute maximum rated value (Note 1)

If you need military/aerospace equipment, please contact the national semiconductor The availability and specifications of the sales office/dealer.

LM2940S，T，MP≤

100 ms 60伏

LM2940CS，T≤1 ms 45伏

内部功耗

[123 ] (Note 2) Internal limited

The highest knot temperature 150

303C

Storage temperature range #

8722

; 65 ℉ C ≤ TJ ≤++ 150 3 C Drawing temperature, wave welding time

to-220

(t) Packing 260 Celsius, 10 seconds

] To-263 (S) Packing 260 degrees Celsius, 4S

SOT-223 (MP) Packaging 260 degrees Celsius, 4S

Static discharge sensitivity (Note 3) 2 kV

Operation conditions (Note 1)

Input voltage 26V

Temperature range

LM2940T, LM2940S 40 degrees C≤tj ≤ 125 degrees C

LM2940CT, LM2940CS 0 degrees C ≤TJ ≤ 125 degrees C

lm2940imp 40 degrees C ≤TJ≤85 degrees C

lm2940wg 55 ° C ≤ Tj≤125 ° C

LM2940LD 40 ° C ≤ TJ≤125 ° C

Electric characteristics

Unless otherwise regulations, vin VO+5V, IO 1A, CO 22 μF. Black body restrictions are suitable for the entire working temperature range of the equipment. All other specifications are suitable for TA TJ 25 ° C

Electrical characteristics (continuity)

Unless otherwise regulations, vIN VO+5V, IO 1A, CO 22 μF. Black body restrictions are suitable for the entire working temperature range of the equipment. All other specifications are suitable for TA TJ 25 ℉.

Note 1: The absolute maximum rated value refers to the limit value that the device may be damaged. The operating conditions are the conditions of the equipment but the specifications may not be guaranteed. For guarantee specifications and test conditions, see electrical characteristics.

Note 2: The maximum allowable power consumption is the maximum knot temperature TJ, the pair of environmental thermal resistance θJa and environmental temperature, TA. The maximum allowable power consumption will cause the mold temperature to be too high, and the regulator will enter the heat shutdown state. The value of θja (for the device in the static air of the radiator) for TO-220 package is 60 ° C/W, for the TO-263 package to 80 ° C/W, for SOT-223 packaging at 174 ° C/W Essence The effective values of θJa can be reduced by using the radiator (for specific information about heat dissipation, see the application prompts). The θja value of the LLP package depends on the PCB tracking area, tracking materials, layers and heat -passing holes. In order to improve the LLP package, refer to the application annotation AN-1187. It is recommended to place 6 pass holes under the center pad to improve thermal performance.

Note 3: ESD rated value is based on human model, 100 PF discharge through 1.5 kΩ.

Note 4: All limits are only in TA TJ 25 ° C (standard font) or the entire indicator deviceThere is a guarantee within the working temperature range (black font). All limits at TA TJ 25 ° C have been produced by 100%production test. Use standard statistical quality control to ensure all the limit methods at extreme temperatures through correlation.

Note 5: The limit is only guaranteed by TA TJ 25 ° C (standard font) or the entire working temperature range of the device (black body font). All limits have passed 100%production testing to calculate the quality level of the factory.

Note 6: The output current decreases as the temperature rises, but it will not drop below 1A at the highest prescribed temperature.

] Program prompt

External capacitors

The output capacitor is important to keep the stabilizer stable. It must meet the requirements of the two ESR requirements (equivalent series resistance) and minimum electricity capacity.

Minimum capacitance: The minimum output capacitor required to maintain stability is 22 μF (the value can increase infinitely). The larger the output capacitor value, the better the transmission response.

ESR limit: if it is too high or too low. The relationship between the acceptable range of ESR and the load current is shown in the figure below. The output capacitor must meet these requirements, or may cause oscillation.

It is important to note that for most capacitors, ESR is specified at room temperature. However, designers must ensure that ESR is kept within the entire design work temperature range of the existing limit. For aluminum electrolytic capacitors, ESR will increase when temperature drops from 25 degrees Celsius to -40 degrees Celsius. This capacitor is not suitable for low temperature operation. The solid pillar capacitor has a more stable ESR temperature, but it is more expensive than aluminum electrolytic. Sometimes the economic effective method adopted is

Application prompt (continued)

Parallel aluminum electrolytic groove with solid 钽

The ratio of total capacitance to aluminum is about 75/ 25%greater value. If the two capacitors are connected in parallel, the effective ESR is parallel to two individual values. The flattened " ESR ”will prevent effective ESR from low temperature. Heading may require radiator