LM3241
SNOSB38B –JANUARY 2009–REVISED APRIL 2013
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Dynamically Adjustable Output Voltage
The LM3241 features dynamically adjustable output voltage to eliminate the need for external feedback resistors.
The output can be set from 0.6V to 3.4V by changing the voltage on the analog VCON pin. This feature is useful
in PA applications where peak power is needed only when the handset is far away from the base station or when
data is being transmitted. In other instances the transmitting power can be reduced. Hence the supply voltage to
the PA can be reduced, promoting longer battery life. See Setting the Output Voltage in the APPLICATION
INFORMATION section for further details. The LM3241 moves into Pulse Skipping mode when duty cycle is over
approximately 92% or less than approximately 15%, and the output voltage ripple increases slightly.
Thermal Overload Protection
The LM3241 has a thermal overload protection function that operates to protect itself from short-term misuse and
overload conditions. When the junction temperature exceeds around 150°C, the device inhibits operation. Both
the PFET and the NFET are turned off. When the temperature drops below 125°C, normal operation resumes.
Prolonged operation in thermal overload conditions may damage the device and is considered bad practice.
Soft Start
The LM3241 has a soft-start circuit that limits in-rush current during startup. During startup the switch current limit
is increased in steps. Soft start is activated if EN goes from low to high after VIN reaches 2.7V.
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