LM2990| Datasheet

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LM2990 Negative Low Dropout Regulator

June 2005

LM2990 Negative Low Dropout Regulator
General Description
The LM2990 is a three-terminal, low dropout, 1 ampere negative voltage regulator available with fixed output voltages of -5, -5.2, -12, and -15V. The LM2990 uses new circuit design techniques to provide low dropout and low quiescent current. The dropout voltage at 1A load current is typically 0.6V and a guaranteed worstcase maximum of 1V over the entire operating temperature range. The quiescent current is typically 1 mA with 1A load current and an input-output voltage differential greater than 3V. A unique circuit design of the internal bias supply limits the quiescent current to only 9 mA (typical) when the regulator is in the dropout mode (VOUT - VIN 3V). Output voltage accuracy is guaranteed to 5% over load, and temperature extremes. The LM2990 is short-circuit proof, and thermal shutdown includes hysteresis to enhance the reliability of the device when overloaded for an extended period of time. The LM2990 is available in a 3-lead TO-220 package and is rated for operation over the automotive temperatu
re range of -40 C to +125 C.

Features
n n n n n n n 5% output accuracy over entire operating range Output current in excess of 1A Dropout voltage typically 0.6V at 1A load Low quiescent current Internal short circuit current limit Internal thermal shutdown with hysteresis Functional complement to the LM2940 series

Applications
n Post switcher regulator n Local, on-card, regulation n Battery operated equipment

Typical Application

01080101

*Required if the regulator is located further than 6 inches from the power supply filter capacitors. A 1 uF solid tantalum or a 10 uF aluminum electrolytic capacitor is recommended. **Required for stability. Must be at least a 10 uF aluminum electrolytic or a 1 uF solid tantalum to maintain stability. May be increased without bound to maintain regulation during transients. Locate the capacitor as close as possible to the regulator. The equivalent series resistance (ESR) is critical, and should be less than 10 over the same operating temperature range as the regulator.

Ordering Information and Connection Diagrams
Temperature Range -40 C to +125 C -55 C to +125 C Output Voltage -5.0 LM2990T-5.0 LM2990S-5.0 LM2990J-5.0-QML 5962-9571101QEA LM2990WG5.0-QML 5962-9571101QXA -5.2 LM2990T-5.2 -12 LM2990T-12 LM2990S-12 LM2990J-12-QML 5962-9571001QEA -15 LM2990T-15 LM2990S-15 LM2990J-15-QML 5962-9570901QEA TO-220 TO-263 J16A WG16A Package

2005 National Semiconductor Corporation

DS010801

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