{"id":3033,"date":"2026-03-17T23:18:38","date_gmt":"2026-03-17T23:18:38","guid":{"rendered":"https:\/\/www.simonk.si\/?p=3033"},"modified":"2026-03-17T23:18:38","modified_gmt":"2026-03-17T23:18:38","slug":"usb-pd-power-delivery","status":"publish","type":"post","link":"https:\/\/www.simonk.si\/?p=3033","title":{"rendered":"USB-PD (power delivery)"},"content":{"rendered":"

Ever thought about USB PD (power delivery) and how it really works? Below you can see simple example of power supply to device communication, where device requests 20V @ 1.5A. <\/p>\n

All bottom data was captured with logic analyzer with some home-brewed circuit. Voltage levels on USB CC lines are 0.9 V, therefore you need some kind of level shifter to capture the data. Comparator circuit works the best.<\/p>\n

Complete transmission cycle with voltage output. At the beginning it all starts with 5V, but after approx 0.5s, it goes up slowly and controlled to 20V.<\/p>\n

\"\"<\/a><\/p>\n

\"\"<\/a><\/p>\n

Part 1 – 3x SOURCE CAP <\/h3>\n

Power supply tells the device which options are available 3 times.<\/p>\n

\"\"<\/a><\/p>\n

Part 2 (after 200ms) – SOURCE CAP again <\/h3>\n

Repeats available options.<\/p>\n

\"\"<\/a><\/p>\n

Part 2 – Device request + CRC<\/h3>\n

Then device requests what is needed.<\/p>\n

\"\"<\/a><\/p>\n

Part 2 – Power supply accepts request + CRC<\/h3>\n

Power supply can accept this request (like in this example) or reject it. If rejected, then device will get 5V and 0.9A only. <\/p>\n

\"\"<\/a><\/p>\n

Part 3 (after changed to new voltage \/ power) – PS RDY <\/h3>\n

If all good, when new voltage is set and stable, power supply tells that power is good and ready to use.<\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Ever thought about USB PD (power delivery) and how it really works? Below you can see simple example of power supply to device communication, where device requests 20V @ 1.5A. All bottom data was captured with logic analyzer with some home-brewed circuit. Voltage levels on USB CC lines are 0.9…<\/p>\n

Read More<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[97,99,98,96],"class_list":["post-3033","post","type-post","status-publish","format-standard","hentry","category-electronics","tag-power-delivery","tag-usb","tag-usb-cc","tag-usb-pd"],"yoast_head":"\nUSB-PD (power delivery) - simonk.si<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.simonk.si\/?p=3033\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"USB-PD (power delivery) - simonk.si\" \/>\n<meta property=\"og:description\" content=\"Ever thought about USB PD (power delivery) and how it really works? 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