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When you're diving into electronics, choosing the right voltage regulator can feel a bit like picking the right charger for your phone. Both might look similar, but they serve different needs. That’s where the LM3480IM3X-3.3/NOPB and LM3940 come in — two popular low-dropout (LDO) regulators that might just make or break your project if you don’t pick wisely.
In this article, we’ll walk through what makes these voltage regulators tick, how they’re different, where they shine, and most importantly — which one might be the better fit for your project. Ready to clear the confusion? Let’s dive in.
Think of a voltage regulator as the “babysitter” for your electronic devices. Its job is to ensure that the components get the voltage they need — nothing more, nothing less. Without it, you risk burning out sensitive parts or watching your circuits misbehave.
The LM3480IM3X-3.3/NOPB is a fixed-output low-dropout regulator that delivers 3.3V from higher voltage inputs. It’s manufactured by Texas Instruments and comes in a small SOT-23-3 package. Despite its size, it’s pretty mighty for lightweight applications.
Quick highlights:
Fixed 3.3V output
Up to 100 mA output current
Excellent line/load regulation
The LM3940 is another Texas Instruments creation, but this one is designed specifically for converting 5V down to 3.3V. It's also an LDO but with a higher current output, making it a go-to for more power-hungry tasks.
Quick highlights:
Fixed 3.3V output
Up to 1A output current
Optimized for 5V to 3.3V conversions
If you’re working with higher input voltages (say 12V or 24V), the LM3480IM3X-3.3/NOPB offers more flexibility. The LM3940 prefers a narrow range — ideally designed for 5V-to-3.3V drops.
Dropout voltage is like the minimum gap the regulator needs to “breathe.” The LM3940, with its low dropout of 0.5V, is ideal when your input is only slightly above the desired output. LM3480, in contrast, needs about 1.2V of headroom, making it less efficient at small voltage drops.
Analogy: Imagine trying to fill a cup under a slow faucet. The LM3940 works fine even with a trickle, while the LM3480 wants a steady stream.
If you need to power multiple devices or something a bit more demanding — LM3940’s 1A output will suit you better. On the other hand, LM3480 is more suitable for low-current applications like small sensors or microcontrollers.
More current means more heat. The LM3940 can run hot under load, so it usually needs a heat sink or decent ventilation. The LM3480, being a lower-power device, runs cool and rarely demands thermal management.
LM3480IM3X-3.3/NOPB comes in a tiny SOT-23-3 package — perfect for compact PCBs.
LM3940 offers larger TO-220 and TO-263 packages, which are great for mounting with heat sinks and handling higher currents.
Both regulators offer decent power supply ripple rejection (PSRR). But if you’re building audio or RF circuits, LM3480 has a slight edge with its stable performance and low output noise at lower loads.
Want a no-fuss build? LM3480 is great for minimalist setups. It usually needs just one capacitor. LM3940, with its higher current demands, often requires more external components and careful layout to avoid instability or heat issues.
LM3480IM3X-3.3/NOPB is typically cheaper due to its lower current specs and small size.
LM3940 might cost more, especially with larger packages and heat sink requirements.
Availability-wise, both are widely stocked by suppliers like Digi-Key, Mouser, and Ovaga.
Pros:
Compact and space-saving
Handles wide input range
Low noise and easy to use
Cons:
Low output current (100 mA)
Not suitable for power-hungry devices
Pros:
High output current (up to 1A)
Excellent for 5V to 3.3V conversion
Reliable under higher loads
Cons:
Needs good thermal design
Narrow input voltage range
Larger footprint
So, which one should you choose?
If you’re building a low-power gadget, want something small and easy, and can afford a slightly higher input voltage — LM3480IM3X-3.3/NOPB is your winner.
But if your project demands more juice, especially from a 5V rail to 3.3V, and you’re ready to deal with heat and size — then LM3940 takes the crown.
In short: Go LM3480 for simplicity, LM3940 for strength.