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 heat sink.
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.
Features:-
- 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
Specification:-
| Parameter | Specification |
| Part number | LM3940 |
| 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 |
| Package Group | DDPAK/TO-263 | 3, TO-220 | 3, SOT-223 | 4 |
| Regulated outputs (#) | 1 |
| Operating temperature range ( C ) | -40 to 125 |
| Thermal resistance θJA (°C/W) | 23 |
| Noise (uVrms) | 150 |
| Rating | See Data Sheet |
| PSRR @ 100 KHz (dB) | 32 |
| Accuracy (%) | 2.5 |
| Dropout voltage (Vdo) (Typ) (mV) | 310 |
| Iq (Typ) (mA) | 0.11 |
| Package size: mm2:W x L (PKG) | 3DDPAK/TO-263: 155 mm2: 15.24 x 10.16 (DDPAK/TO-263 | 3) |
| 3TO-220: 47 mm2: 4.58 x 10.16 (TO-220 | 3) | |
| 4SOT-223: 46 mm2: 7 x 6.5 (SOT-223 | 4) |
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