{"id":474,"date":"2023-06-28T07:49:00","date_gmt":"2023-06-28T07:49:00","guid":{"rendered":"https:\/\/copperfiction.com\/?p=474"},"modified":"2026-04-09T21:50:17","modified_gmt":"2026-04-09T21:50:17","slug":"custom-solid-state-relays-power-distribution-and-passive-cooling","status":"publish","type":"post","link":"https:\/\/copperfiction.com\/index.php\/2023\/06\/28\/custom-solid-state-relays-power-distribution-and-passive-cooling\/","title":{"rendered":"[026] CUSTOM SOLID STATE RELAYS"},"content":{"rendered":"\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"900\" height=\"400\" src=\"https:\/\/copperfiction.com\/wp-content\/uploads\/2026\/04\/image1-12.png\" alt=\"\" class=\"wp-image-475\" srcset=\"https:\/\/copperfiction.com\/wp-content\/uploads\/2026\/04\/image1-12.png 900w, https:\/\/copperfiction.com\/wp-content\/uploads\/2026\/04\/image1-12-300x133.png 300w, https:\/\/copperfiction.com\/wp-content\/uploads\/2026\/04\/image1-12-768x341.png 768w\" sizes=\"auto, (max-width: 900px) 100vw, 900px\" \/><\/figure>\n\n\n\n<p><\/p>\n\n\n\n<p>Replacing mechanical relays with MOSFET-based SSRs is always appealing. No moving parts, no contact wear, silent switching. But a custom SSR power distribution board is a lot more than a simple switching circuit.<\/p>\n\n\n\n<p>Each channel has a MOSFET running in full conduction. The dominant loss is conduction loss: P = I\u00b2 \u00d7 Rds(on). That makes Rds(on) a critical parameter, directly tied to thermal performance. The target was to keep junction temperature rise under +50\u00b0C above ambient with passive cooling only \u2014 which meant careful heatsink selection, thermal interface material, and mounting quality.<\/p>\n\n\n\n<p>Current sensing is done with Hall-effect sensors: no resistive losses in the power path, natural galvanic isolation. The ATSAMD20 uses those readings for overcurrent protection and RS485 telemetry. One of those projects where every design choice genuinely affects every other one.<\/p>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Replacing mechanical relays with MOSFET-based SSRs is always appealing. No moving parts, no contact wear, silent switching. But a custom SSR power distribution board is a lot more than a simple switching circuit. Each channel has a MOSFET running in full conduction. The dominant loss is conduction loss: P = I\u00b2 \u00d7 Rds(on). That makes &#8230; <a title=\"[026] CUSTOM SOLID STATE RELAYS\" class=\"read-more\" href=\"https:\/\/copperfiction.com\/index.php\/2023\/06\/28\/custom-solid-state-relays-power-distribution-and-passive-cooling\/\" aria-label=\"Read more about [026] CUSTOM SOLID STATE RELAYS\">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":[68],"tags":[73,72,74],"class_list":["post-474","post","type-post","status-publish","format-standard","hentry","category-68","tag-atsamd20g18a-au","tag-logic","tag-ssr-solid-state-relay"],"_links":{"self":[{"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/posts\/474","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/comments?post=474"}],"version-history":[{"count":7,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/posts\/474\/revisions"}],"predecessor-version":[{"id":634,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/posts\/474\/revisions\/634"}],"wp:attachment":[{"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/media?parent=474"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/categories?post=474"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/copperfiction.com\/index.php\/wp-json\/wp\/v2\/tags?post=474"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}