LP2952-N Datasheet, PDF (16/41 Pages) Texas Instruments – LP295x Adjustable Micropower Low-Dropout Voltage Regulators

LP2952-N, LP2952A, LP2953, LP2953A
SNVS095F – MAY 2004 – REVISED MARCH 2015
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Feature Description (continued)
7.3.5 Short-Circuit Protection (Current Limit)
The internal current limit circuit is used to protect the LDO against high-load current faults or shorting events. The
LDO is not designed to operate in a steady-state current limit. During a current-limit event, the LDO sources
constant current. Therefore, the output voltage falls when load impedance decreases. Note also that if a current
limit occurs and the resulting output voltage is low, excessive power may be dissipated across the LDO resulting
in a thermal shutdown of the output. A thermal foldback feature limits the short-circuit current to protect the
regulator from damage under all load conditions. If the OUT pin is forced below 0 V before SHUTDOWN goes
high and the load current required exceeds the thermal foldback current limit, the device may not start up
correctly.
7.3.6 Thermal Protection
The device contains a thermal shutdown protection circuit to turn off the output current when excessive heat is
dissipated in the LDO. The thermal time-constant of the semiconductor die is fairly short, and thus the output
cycles on and off at a high rate when thermal shutdown is reached until the power dissipation is reduced. The
internal protection circuitry of the device is designed to protect against thermal overload conditions. The circuitry
is not intended to replace a proper heatsink. Continuously running the device into thermal shutdown degrades its
reliability.
7.3.7 Automatic Output Discharge
Both LP2952 and LP2953 employ an internal 50-mA (typical) pulldown to discharge the output when the
SHUTDOWN pin is low and the output is disabled.
7.4 Device Functional Mode
7.4.1 Shutdown Mode
When pulling the SHUTDOWN pin to low level, the LP2952 and LP2953 will enter shutdown mode, and a very
low quiescent current is consumed. This function is designed for applications which needs a shutdown mode to
effectively enhance battery life cycle. When the SHUTDOWN pin is low the automatic output discharge circuity
will be active. See Application Information for more details.
7.4.2 Operation with 30 V ≥ V_IN > V_OUT(TARGET) + 1 V
The device operate if the input voltage is equal to, or exceeds, V_OUT(TARGET) + 1 V, and SHUTDOWN is pulled to
high level. At input voltages below the minimum V_IN requirement, the devices do not operate correctly and output
voltage may not reach target value.
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