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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| Part number | Order | Output options | Iout (Max) (A) | Vin (Max) (V) | Vin (Min) (V) | Vout (Max) (V) | Vout (Min) (V) | Fixed output options (V) | Package Group | Features | Regulated outputs (#) | Operating temperature range (C) | Thermal resistance θJA (°C/W) | Noise (uVrms) | Approx. price (US$) | Rating | Output capacitor type | PSRR @ 100 KHz (dB) | Accuracy (%) | Vdo (Typ) (mV) | Iq (Typ) (mA) | Package size: mm2:W x L (PKG) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| LM3940 |
|
Fixed Output | 1 | 5.5 | 4.5 | 3.3 | 3.3 | 3.3 |
DDPAK/TO-263 | 3
SOT-223 | 4 TO-220 | 3 |
|
1 | -40 to 125 | 23 | 150 | 0.55 | 1ku | Catalog | Non-Ceramic | 32 | 2.5 | 310 | 0.11 |
3DDPAK/TO-263: 155 mm2: 15.24 x 10.16 (DDPAK/TO-263 | 3)
4SOT-223: 46 mm2: 7 x 6.5 (SOT-223 | 4) See datasheet (TO-220) |
| LP3872 |
|
Fixed Output | 1.5 | 7 | 2.5 | 5 | 1.8 |
1.8
2.5 3.3 5 |
DDPAK/TO-263 | 5
SOT-223 | 5 |
Enable
Power Good |
1 | -40 to 125 | 40 | 100 | 1.41 | 1ku | Catalog | Ceramic | 2 | 380 | 6 |
5DDPAK/TO-263: 155 mm2: 15.24 x 10.16 (DDPAK/TO-263 | 5)
5SOT-223: 45 mm2: 6.96 x 6.5 (SOT-223 | 5) |
