Product details

Output options Fixed Output Iout (Max) (A) 1 Vin (Max) (V) 5.5 Vin (Min) (V) 4.5 Vout (Max) (V) 3.3 Vout (Min) (V) 3.3 Fixed output options (V) 3.3 Noise (uVrms) 150 Iq (Typ) (mA) 0.11 Thermal resistance θJA (°C/W) 23 Rating Catalog Load capacitance (Min) (µF) 33 Regulated outputs (#) 1 Accuracy (%) 2.5 PSRR @ 100 KHz (dB) 32 Dropout voltage (Vdo) (Typ) (mV) 310 Operating temperature range (C) -40 to 125
Output options Fixed Output Iout (Max) (A) 1 Vin (Max) (V) 5.5 Vin (Min) (V) 4.5 Vout (Max) (V) 3.3 Vout (Min) (V) 3.3 Fixed output options (V) 3.3 Noise (uVrms) 150 Iq (Typ) (mA) 0.11 Thermal resistance θJA (°C/W) 23 Rating Catalog Load capacitance (Min) (µF) 33 Regulated outputs (#) 1 Accuracy (%) 2.5 PSRR @ 100 KHz (dB) 32 Dropout voltage (Vdo) (Typ) (mV) 310 Operating temperature range (C) -40 to 125
SOT-223 (DCY) 4 46 mm² 6.5 x 7 TO-220 (NDE) 3 47 mm² 10.16 x 4.58 TO-263 (KTT) 3 155 mm² 10.16 x 15.24
  • Input Voltage Range: 4.5 V to 5.5 V
  • Output Voltage Specified over Temperature
  • Excellent Load Regulation
  • Specified 1-A Output Current
  • Requires only One External Component
  • Built-in Protection against Excess Temperature
  • Short-Circuit Protected
  • Input Voltage Range: 4.5 V to 5.5 V
  • Output Voltage Specified over Temperature
  • Excellent Load Regulation
  • Specified 1-A Output Current
  • Requires only One External Component
  • Built-in Protection against Excess Temperature
  • Short-Circuit Protected

The LM3940 is a 1-A low-dropout regulator designed to provide 3.3 V from a 5-V supply.

The LM3940 is ideally suited for systems which contain both 5-V and 3.3-V logic, with prime power provided from a 5-V bus.

Because the LM3940 is a true low dropout regulator, it can hold its 3.3-V output in regulation with input voltages as low as 4.5 V.

The TO-220 package of the LM3940 means that in most applications the full 1 A of load current can be delivered without using an additional heatsink.

The surface mount DDPAK/TO-263 package uses minimum board space, and gives excellent power dissipation capability when soldered to a copper plane on the PC board.

The LM3940 is a 1-A low-dropout regulator designed to provide 3.3 V from a 5-V supply.

The LM3940 is ideally suited for systems which contain both 5-V and 3.3-V logic, with prime power provided from a 5-V bus.

Because the LM3940 is a true low dropout regulator, it can hold its 3.3-V output in regulation with input voltages as low as 4.5 V.

The TO-220 package of the LM3940 means that in most applications the full 1 A of load current can be delivered without using an additional heatsink.

The surface mount DDPAK/TO-263 package uses minimum board space, and gives excellent power dissipation capability when soldered to a copper plane on the PC board.

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Technical documentation

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* Data sheet LM3940 1-A Low-Dropout Regulator for 5-V to 3.3-V Conversion datasheet (Rev. G) PDF | HTML 16 Feb 2015
Application note AN-1061 Power Conversion in Line-Powered Equipment (Rev. B) 23 Apr 2013

Design & development

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Package Pins Download
DDPAK/TO-263 (KTT) 3 View options
SOT-223 (DCY) 4 View options
TO-220 (NDE) 3 View options

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