EYE ON NPI – onsemi NIV3071 4-Channel eFuse Solution

Adafruit Industries

This week's EYE ON NPI is another onsemi device - this week we're looking at the NIV3071 4-Channel eFuse Solution (https://www.digikey.com/en/product-highlight/o/on-semi/niv3071-4-channel-efuse-solution) a power distribution manager that can lets you manage a product with a lot of power domains and supplies using just a couple GPIO pins. This week's product is an upgrade from the covered-earlier NIS5420 (https://blog.adafruit.com/2021/09/09/eye-on-npi-onsemi-efuse-porfolio-eyeonnpi-digikey-onsemi-digikey-adafruit/) - with a higher 8~60V input range, and 4 independently-controlled channels. When people first meet fuses, they usually see and think of classic 'wire' fuses (https://www.digikey.com/en/products/detail/bel-fuse-inc/5ST-200-R/1009012) with ceramic or glass or thermoplastic bodies, and a thin wire inside. When too much current goes through the fuse wire, it gets hotter and hotter and eventually melts, cutting off the load from the source voltage. These kinds of fuses are super cheap, very-very-low resistance, easy to find at any hardware store, and there's lots of suppliers with various current limits. However, they're one-shot usage only and only good for over-current, can't act as switches/sequencers. You need to have a way for customers to access the fuse in order to replace it. For those reasons, a lot of engineers prefer going with 'poly fuses' - fuses that are easy to mount into a circuit that auto-reset after a time (usually minutes) so that a temporary overload doesn't make the device a brick so quickly. For example, we have a chunky 24V 5A hold / 10 A trip polyfuse (https://www.digikey.com/en/products/detail/littelfuse-inc/2016L260-24MR/6347052) on the Sparkle Motion board design (https://www.adafruit.com/product/6100), designed to protect folks who accidentally have a short in the output LED strings, and want to avoid damaging the power supply or main board. Poly-fuses are a great step-up from plain wire fuses: they're fairly inexpensive, available from lots of suppliers with various current limits, and best of all the fuse auto-resets after cooling down. However, like wire fuses, they're good for over-current, can't be reset, and have some variation depending on ambient temperature: you may trip 50% higher if its cold, or lower if its hot. Thus the next generation of fuses: eFuses (https://www.digikey.com/en/product-highlight/o/on-semi/efuse-automotive-circuit-protection)! As you could imagine, these are pure-silicon fuses, with a chunky N-FET that acts as the cut-off switch, and current limiting managed as an analog feedback loop that will cut the FET when too high. We get the resetability of a polyfuse, with additional control like sequence-able enable pins and under-voltage lockout. Note that some eFuses also can do over-voltage clamps and negative voltage protection, but the NIV3071 (https://www.digikey.com/short/3v0thr1p) doesn't contain these protections, so you may want to implement those protections separately. Especially designed for automotive power systems, which tend to be 12V/24V/36V/48V multiples, the NIV3071 (https://www.digikey.com/short/3v0thr1p) is AEC−Q100 qualified and PPAP capable (https://www.onsemi.com/pub/collateral/tnd6284-d.pdf). The use of eFuses is becoming popular as cars have become more computerized and electrified, with each 'zone' in a car (https://www.onsemi.com/solutions/automotive/zonal-architecture) - such as entertainment, communication, lighting, charging and sensors - all needing separate power management. If you don't need automotive qualifications, the functionally-compatible NIS3071 (https://www.digikey.com/short/9v2dmvhf) is a couple of cents cheaper. This family of eFuses is good for up to 60V and 2.5A per channel, but if you need more per channel you can just double or triple them up to add 2.5A per. If you want less per channel, to protect low-power devices from overheating or accidental shorts, the current limit can be reduced with an external resistor. And of course, you can turn on/off each channel with a GPIO enable pin: great for sequencing your power chain to reduce stress on the power supply from inrush current, or to allow each section to stabilize and go through self-test. For your next power supply design, the onsemi NIV3071 (https://www.digikey.com/short/3v0thr1p) and NIS3071 (https://www.digikey.com/short/9v2dmvhf) offer high-voltage, high-current control in a small package and a great price. Both are in stock right now at DigiKey for immediate shipment, so you can book today and start integration by tomorrow afternoon.