LM2940 DATASHEET PDF

Perhaps I have misunderstood this specification? Please see updated question with attached schematic. The vishay datasheet shows change of ESR with frequency. For reference, this is the LM datasheet.

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Nominally 12 Volt Lead acid batteries typically operate in the range of When under charge, the voltage can easily get over 14V — sufficient to cause damage to sensitive 12V equipment.

Voltage Regulators A voltage regulator is a device which takes an input voltage and outputs a stable fixed voltage. Variable voltage regulators are available such as the very useful LMT which the user can set to output any required voltage 1. For the more commonly required voltages of 3. Unfortunately the regulators mentioned above have quite a high voltage drop — typically up to 3 Volts. To get around this problem low dropout regulators were developed.

A low dropout regulator supplies a fixed output voltage with a typical voltage drop of just 0. This makes them perfect for use with 12 Volt lead acid batteries.

Ideally a lead acid battery should never be allowed to get below It can output up to 1 Amp at a fixed 12 Volts DC with a dropout of just 0. It can accept input voltages from 5. When the input voltage is below With a current draw of 0. If high voltages, or high currents between 0. The LMCT range has internal short circuit and thermal overload protection, so you need to make a special effort to damage one.

Using the LM Below is a diagram showing the three legs of the LM — one for the input voltage, one for the output voltage, and one for the ground: In order to maintain a stable 12 Volt output, an external capacitor of at least 22uF must be used to smooth off the output from the integrated circuit IC , with the capacitor located as close to the IC as possible. If you need a 12 Volt voltage regulator to supply more than 1 Amp of current to power an LCD television, laptop, or large amount of lighting, then take a look at our article on the Amperor ADPDC

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National Semiconductor

I was using datashet above to supply 5v to my Atmegap-pu project in my automotive environment for controlling the signal that datqsheet on some lights via Mosfet. Email Required, but never shown. This capacitor must be rated over the same operating temperature range as the regulator and 2 the ESR is critical — see curve. Sign up using Email and Password. What is the input voltage? Tom Wilson 68 7. Could that contribute to the oscillation?

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LM2940 direct replacement for LM7805?

Furthermore, a quiescent current reduction circuit has been included which reduces the ground current when the differential between the input voltage and the output voltage exceeds approximately 3V. The quiescent current with 1A of output current and an inputoutput differential of 5V is therefore only 30 mA. During line transients, such as load dump when the input voltage can momentarily exceed the specified maximum operating voltage, the regulator will automatically shut down to protect both the internal circuits and the load. Familiar regulator features such as short circuit and thermal overload protection are also provided.

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