ZHCSAW6K March 2009 – April 2019 LM2840 , LM2841 , LM2842
PRODUCTION DATA.
The devices have circuitry that is used in conjunction with the SHDN pin to limit the inrush current on start-up of the DC/DC switching regulator. The SHDN pin in conjunction with a RC filter is used to tailor the soft start for a specific application. When a voltage applied to the SHDN pin is between 0 V and up to 2.3 V it causes the cycle-by-cycle current limit in the power stage to be modulated for minimum current limit at 0 V up to the rated current limit at 2.3 V. Thus controlling the output rise time and inrush current at start-up. The resistor value must be selected so the current injected into the SHDN pin is greater then the leakage current of the SHDN pin (1.5 µA) when the voltage at SHDN is equal or greater then 2.3 V.