Manufacturer part number LP2981AIM5-3.0
Part Number LP2981AIM5-30
Operating junction temperature −40 ~ 125°C
Power dissipation Internally limited
Input supply voltage (survival) -0.3 ~ 16V
Input supply voltage (operating) 2.1 ~ 16V
Shutdown input voltage (survival) -0.3 ~ 16V
Output voltage (survival) -0.3 ~ 9V
Input-output voltage (survival) -0.3 ~ 16V
Storage temperature -65 ~ 150°C

LP2981-N Micropower 100-mA Ultralow Dropout Regulator in SOT-23 Package


  • Operating Input Voltage Range: 2.1 V to 16 V
  • Ultralow-Dropout Voltage
  • Output Voltage Accuracy 0.75% (A Grade)
  • Specified 100-mA Output Current
  • < 1-μA Quiescent Current when Shutdown
  • Low Ground Pin Current at All Load Currents
  • High Peak Current Capability (300 mA Typical)
  • Wide Supply Voltage Range (16 V Maximum)
  • Fast Dynamic Response to Line and Load
  • Low ZOUT Over Wide Frequency Range
  • Overtemperature and Overcurrent Protection
  • −40°C to 125°C Junction Temperature Range


  • Cellular Phones
  • Palmtop and Laptop Computers
  • Personal Digital Assistants (PDA)
  • Camcorders, Personal Stereos, Cameras


The LP2981-N is a 100-mA, fixed-output voltage regulator designed specifically to meet the requirements of battery-powered applications.

Using an optimized Vertically Integrated PNP (VIP) process, the LP2981-N delivers unequaled performance in all specifications critical to batterypowered designs:

Dropout Voltage: Typically 200 mV at 100-mA load, and 7 mV at 1-mA load.

Ground Pin Current: Typically 600 μA at 100-mA load, and 80 μA at 1-mA load.

Sleep Mode: Less than 1-μA quiescent current when ON/OFF pin is pulled low.

Precision Output: 0.75% tolerance output voltages available (A grade).

Assorted voltage options, from 2.5 V to 5 V, are available as standard products.

Detailed Description

The LP2981-N is a 100-mA, fixed-output voltage regulator designed specifically to meet the requirements of battery-powered applications. Available in assorted output voltages from 2.5 V to 5 V, the device has an output tolerance of 0.75% for the A grade (1.25% for the non-A version). Using a VIP process, the LP2981-N contains these features to facilitate battery-powered designs:

  • Fixed 5-V, 3.6-V, 3.3-V, 3-V, and 2.5-V output versions
  • Very high-accuracy 1.23-V reference
  • Low-dropout voltage, typical dropout of 200 mV at 100-mA load current and 7 mV at 1-mA load
  • Low ground current, typically 600 μA at 100-mA load and 80 μA at 1-mA load
  • A sleep mode feature is available, allowing the regulator to consume only 1 µA (typical) when the ON/OFF pin is pulled low.
  • Overtemperature protection and overcurrent protection circuitry is designed to safeguard the device during unexpected conditions.

Feature Description

Multiple Voltage Options

To meet the different application requirements, the LP2981-N provides multiple fixed output options from 2.5 V to 5 V.

High-Accuracy Output Voltage

With special careful design to minimize all contributions to the output voltage error, the LP2981-N distinguishes itself as a very high-accuracy output voltage micropower LDO. This includes a tight initial tolerance (0.75% typical), extremely good line regulation (0.007%/V typical), and a very low output voltage temperature coefficient, making the part an ideal low-power voltage reference.

Ultra-Low-Dropout Voltage

Generally speaking, the dropout voltage often refers to the voltage difference between the input and output voltage (VDO = VIN – VOUT), where the main current pass-FET is fully on in the ohmic region of operation and is characterized by the classic RDS(ON) of the FET. VDO indirectly specifies a minimum input voltage above the nominal programmed output voltage at which the output voltage is expected to remain within its accuracy boundary.

Low Ground Current

LP2981-N uses a vertical PNP process which allows for quiescent currents that are considerably lower than those associated with traditional lateral PNP regulators, typically 600 μA at 100-mA load and 80 μA at 1-mA load.

Sleep Mode

When pulling the ON/OFF pin to low level, LP2981-N will enter sleep mode, and less than 1-μA quiescent current is consumed. This function is designed for the application which needs a sleep mode to effectively enhance battery life cycle.

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. 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 foldback feature limits the short-circuit current to protect the regulator from damage under all load conditions. If OUT is forced below 0 V before EN goes high and the load current required exceeds the foldback current limit, the device may not start up correctly.

Thermal Protection

The LP2981-N 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

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