This week’s EYE ON NPI is the ideal component for your next power supply design, it’s Nexperia’s NID5100 Ideal Diodes, a simple design improvement to Schottky diodes or simple P-FET polarity protection.

This small and low-cost component from Nexperia is their first ‘ideal diode’, and can be used in many low voltage power supply setups to reduce power loss and get you more product life from your battery

Diodes, who doesn’t love them? You put some P-doped Silicon next to N-doped Silicon and before you know it, you have accidentally semiconductored! Make them big enough and you can even solve global warming. We use diodes all the time, and they’re particularly useful for power supplies since they make sure current only goes one way.

We often use them in front of a DC jack, between the power input and the circuitry: this keep the voltage polarity positive with respect to ground, since most modern microelectronic components want between 3-24VDC.

Or, as an OR: either battery or USB power are hot-swapped so that whichever gives the highest voltage will run the downstream electronics – see our Trinket M0 schematic for a simple example.

When we first started electronics we’d use the classic 1N4001 – this low cost diode can handle high currents and about 1A continuous, with about 1-2V forward drop. When we did +12V power to an LM7805 this was fine, we have 5V to burn.

Sometimes if we were feeling fancy we’d use a Schottky diode like the 1N5817 which has about 0.7V drop, these are often used for boost or buck converters where you don’t want to lose efficiency in your free-wheeling diode switch.

But when using a 3.7V nominal voltage lipoly battery into a 3.3V regulator, we have to dial it down – even 0.7V is too high – so we’d often reach for a lower-drop Schottky like the Nexperia PMEG2010. We still use this part a lot, but we could do better with an Ideal Diode like the NID5100!

Ideal diodes are as close as possible to the platonic ideal of a diode as possible: Forward conduction only, with zero reverse conduction, and minimal voltage drop.

Sometimes folks try to mimic this with a reversed P-FET and yes this will give minimal forward voltage drop for polarity protection, but it has ‘infinite’ reverse leakage instead of close-to-zero.

The NID5100 is more complex, with additional circuitry for driving the P-FET. It can be used either as a polarity protection for a DC or battery input where there’s risk of the voltage being inverted, or as an OR-ing voltage select.

Compared to a Schottky, it can handle 1.5A continuous – most basic Schottky’s are 1A – and with a forward voltage drop of only 50mV at 0.1A. The package size and price is also very comparable to a SOT323 diode, in an easy-to-place TSSOP6 and under 10 cents in reel quantity. We also like the extra pins like an Enable, so it can also act as an on/off switch, and a Status pin that lets you know when the diode is conducting: this can be used to detect which power supply is active in an OR setup.

Does the Nexperia NID5100 sound like the ideal solution to reduce heat and power loss in your next product? Yes! And it’s in stock right now at DigiKey for immediate shipment. Order today and you’ll receive your components faster than a diode switching time, for integration into your BOM by tomorrow afternoon.

See the Eye on NPI episode below and the manufacturer video below that.