LM2941, LM2941C

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SNVS770G – JUNE 1999 – REVISED APRIL 2013

ON/OFF

The ON/OFF pin has no internal pull-up or pull-down to establish a default condition and, as a result, this pin

must be terminated externally, either actively or passively.

The ON/OFF pin requires a low level to enable the output, and a high level to disable the output. To ensure

output. If the ON/OFF function is not needed this pin can be connected directly to Ground.

If the ON/OFF pin is being pulled to a high state through a series resistor, an allowance must be made for the

ON/OFF pin current that will cause a voltage drop across the pull-up resistor.

Thermal Overload Protection

155°C.

Should the LM2941 see a fault condition that results in excessive power dissipation and the junction temperature

approaches 155°C, the device will respond by reducing the output current (which reduces the power dissipation)

to hold the junction temperature at 155°C.

Thermal Overload protection is not an ensured operating condition. Operating at, or near to, the Thermal

Overload condition for any extended period of time is not encouraged, or recommended, as this may shorten the

lifetime of the device.

Power Dissipation

application, and the thermal resistance (

device is given by:

(3)

The maximum allowable junction temperature rise (

(4)

The maximum allowable value for junction to ambient Thermal Resistance,

(5)

calculated using the formula:

(6)

Additional information for thermal performance of surface mount packages can be found in AN-1520: A Guide to

Board Layout for Best Thermal Resistance for Exposed Packages (literature number SNVA183), AN-1187:

Leadless Leadframe Package (LLP) (literature number SNOA401), and AN-2020: Thermal Design By Insight, Not

Hindsight (literature number SNVA419).

TO-263 Mounting

The thermal dissipation of the TO-263 package is directly related to the printed circuit board construction and the

amount of additional copper area connected to the TAB.

The TAB on the bottom of the TO-263 package is connected to the die substrate via a conductive die attach

adhesive, and to device pin 3. As such, it is strongly recommend that the TAB area be connected to copper area

directly under the TAB that is extended into the ground plane via multiple thermal vias. Alternately, but not

recommended, the TAB may be left floating (i.e. no direct electrical connection). The TAB must not be connected

to any potential other than ground.

Copyright © 1999–2013, Texas Instruments Incorporated

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