Uploaded August 2026 | Updated September 2026, 2 weeks ago
Take your I2C bus from schematic to fabricated board without the friction — Altium Develop unites design, sourcing, and manufacturing in one connected workflow: altium.com/develop?utm_source=youtube&utm_medium=video&utm_campaign=altium-academy-shorts&utm_content=how-i2c-works-open-drain-and-pull-up-resistors-on-a-pcb
Wiring an I2C bus on a PCB comes down to two signals — serial data (SDA) and serial clock (SCK) — that run out of your main controller and let every peripheral tap directly onto the same two lines. In this clip, Zach Peterson walks through that shared-bus topology on the schematic and the board, showing why I2C is one of the easiest interfaces to route: you simply pull each ASIC's data and clock connections straight off the common bus.
The catch is that I2C is an open-drain protocol, so every device can only pull a line low — a transistor inside the controller dumps the line's charge to ground — and nothing on the bus actively drives it high. That's exactly why you need pull-up resistors: they tie each line up to the power-bus voltage to set the logic-high level while limiting the current that flows into ground each time a transistor switches on. Get this one idea and I2C signaling, SDA/SCL wiring, and pull-up sizing all start to click.
💡 Watch Next:
▶ Full video — I2C and SPI on a PCB Explained!: youtu.be/eheh938ESU0
▶ I2C Explained: How Open-Drain and Pull-Ups Really Work: youtube.com/watch?v=QQlbt4TUlr8
💡 Stay Connected:
Don't forget to like, comment, and subscribe for more in-depth tutorials and tips from @AltiumAcademy Share your thoughts and questions in the comments below!
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Don't forget to follow us on social to stay up-to-date on the latest Altium Academy content.
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The Altium Academy is an online experience created to bring modern education to PCB Designers and Engineers all across the world. Here you can access a vast library of free training and educational content covering everything from basic design to advanced principles and step-by-step walkthroughs. Join industry legends as they share their career knowledge, review real-life design projects, or learn how to leverage one of Altium's leading design tools. No matter your level of experience, the Altium Academy can help you become a better Designer and Engineer!
About Altium LLC
Altium LLC (ASX:ALU), a global software company based in San Diego, California, is accelerating the pace of innovation through electronics. From individual inventors to multinational corporations, more PCB designers and engineers choose Altium software to design and realize electronics-based products.
#altium #i2c #pcbdesign
Take your I2C bus from schematic to fabricated board without the friction — Altium Develop unites design, sourcing, and manufacturing in one connected workflow: altium.com/develop?utm_source=youtube&utm_medium=video&utm_campaign=altium-academy-shorts&utm_content=how-i2c-works-open-drain-and-pull-up-resistors-on-a-pcb
Wiring an I2C bus on a PCB comes down to two signals — serial data (SDA) and serial clock (SCK) — that run out of your main controller and let every peripheral tap directly onto the same two lines. In this clip, Zach Peterson walks through that shared-bus topology on the schematic and the board, showing why I2C is one of the easiest interfaces to route: you simply pull each ASIC's data and clock connections straight off the common bus.
The catch is that I2C is an open-drain protocol, so every device can only pull a line low — a transistor inside the controller dumps the line's charge to ground — and nothing on the bus actively drives it high. That's exactly why you need pull-up resistors: they tie each line up to the power-bus voltage to set the logic-high level while limiting the current that flows into ground each time a transistor switches on. Get this one idea and I2C signaling, SDA/SCL wiring, and pull-up sizing all start to click.
💡 Watch Next:
▶ Full video — I2C and SPI on a PCB Explained!: youtu.be/eheh938ESU0
▶ I2C Explained: How Open-Drain and Pull-Ups Really Work: youtube.com/watch?v=QQlbt4TUlr8
💡 Stay Connected:
Don't forget to like, comment, and subscribe for more in-depth tutorials and tips from @AltiumAcademy Share your thoughts and questions in the comments below!
👉 Subscribe for more: youtube.com/@AltiumAcademy?sub_confirmation=1
Don't forget to follow us on social to stay up-to-date on the latest Altium Academy content.
👉 Follow Altium on TikTok: tiktok.com/@altiumdesigner
👉 Follow Altium on Twitter: twitter.com/altium
👉 Follow Altium on Linkedin: linkedin.com/company/altium
👉 Follow Altium on Facebook: facebook.com/AltiumOfficial
The Altium Academy is an online experience created to bring modern education to PCB Designers and Engineers all across the world. Here you can access a vast library of free training and educational content covering everything from basic design to advanced principles and step-by-step walkthroughs. Join industry legends as they share their career knowledge, review real-life design projects, or learn how to leverage one of Altium's leading design tools. No matter your level of experience, the Altium Academy can help you become a better Designer and Engineer!
About Altium LLC
Altium LLC (ASX:ALU), a global software company based in San Diego, California, is accelerating the pace of innovation through electronics. From individual inventors to multinational corporations, more PCB designers and engineers choose Altium software to design and realize electronics-based products.
#altium #i2c #pcbdesign
