{"id":16360049,"url":"https://github.com/chrisb2/ds3231-breakout","last_synced_at":"2026-03-18T19:07:48.316Z","repository":{"id":82040829,"uuid":"410190471","full_name":"chrisb2/ds3231-breakout","owner":"chrisb2","description":"Low Current RTC Breakout With Super Capacitor Backup","archived":false,"fork":false,"pushed_at":"2021-09-25T21:12:39.000Z","size":1570,"stargazers_count":3,"open_issues_count":0,"forks_count":0,"subscribers_count":2,"default_branch":"main","last_synced_at":"2026-01-05T02:35:12.473Z","etag":null,"topics":["backup","breakout","ds3231","real-time-clock","rtc","supercapacitor"],"latest_commit_sha":null,"homepage":"","language":null,"has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/chrisb2.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE.md","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2021-09-25T06:02:41.000Z","updated_at":"2024-05-21T12:24:59.000Z","dependencies_parsed_at":null,"dependency_job_id":"827fae62-ddb5-4b01-b214-a20bebebc525","html_url":"https://github.com/chrisb2/ds3231-breakout","commit_stats":null,"previous_names":[],"tags_count":0,"template":false,"template_full_name":null,"purl":"pkg:github/chrisb2/ds3231-breakout","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/chrisb2%2Fds3231-breakout","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/chrisb2%2Fds3231-breakout/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/chrisb2%2Fds3231-breakout/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/chrisb2%2Fds3231-breakout/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/chrisb2","download_url":"https://codeload.github.com/chrisb2/ds3231-breakout/tar.gz/refs/heads/main","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/chrisb2%2Fds3231-breakout/sbom","scorecard":null,"host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":286080680,"owners_count":28764588,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2026-01-26T00:37:26.264Z","status":"online","status_checked_at":"2026-01-26T02:00:08.215Z","response_time":59,"last_error":null,"robots_txt_status":"success","robots_txt_updated_at":"2025-07-24T06:49:26.215Z","robots_txt_url":"https://github.com/robots.txt","online":true,"can_crawl_api":true,"host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["backup","breakout","ds3231","real-time-clock","rtc","supercapacitor"],"created_at":"2024-10-11T02:10:23.005Z","updated_at":"2026-01-26T02:06:51.311Z","avatar_url":"https://github.com/chrisb2.png","language":null,"funding_links":[],"categories":[],"sub_categories":[],"readme":"# Low Current RTC Breakout With Super Capacitor Backup\n\n\u003cimg src=\"rtc-ds3231-breakout.jpg\" width=\"200\"\u003e\n\nThis 32x21mm breakout is based on the [DS3231](docs/DS3231.pdf) Real Time Clock (RTC) from Maxim Integrated and a [FT0H474ZF](docs/FT0H474ZF.pdf) 0.47F super capacitor from Kemet for backup power.\n\nThe design powers the DS3231 via the V\u003csub\u003ebat\u003c/sub\u003e input rather than V\u003csub\u003ecc\u003c/sub\u003e, this results in a current consumption of ~3uA, with spikes to 575uA every 65 seconds when temperature conversion occurs. See the electrical characteristics for V\u003csub\u003ecc\u003c/sub\u003e = 0V, V\u003csub\u003ebat\u003c/sub\u003e = 2.3V to 5.5V on page 3 of the data sheet.\n\n## Design Information\n\n![Schematic](rtc-ds3231-schematic.png)\n\n* The schematic shows a DS3231SN which operates accurately below freezing, but the DS3131S can be used if the device is used at room temperature.\n* The [BAT54H](docs/BAT54H.pdf) Schottky diode prevents the super capacitor from powering the connected MCU. It has a forward current of 200mA to allow for the current to charge the super capacitor.\n* R3 has been chosen to limit the super capacitor charge current to ~150mA based on V\u003csub\u003ebat\u003c/sub\u003e being 3.3V. If the input voltage is higher a correspondingly larger value will be required to maintain the maximum current of 150mA.\n\n## PCB\n\nThe design files can be found at [https://oshwlab.com/chrisb2/ds3231-low-power](https://oshwlab.com/chrisb2/ds3231-low-power) and the Gerbers are included in this repository.\n\n![PCB](rtc-ds3231-pcb.png)\n\n## BOM\n\n| Designator | Value | Part |\n|------|-------|----------|\n| - | DS3231SN | 1 |\n| C1 | FT0H474ZF 0.47F | 1 |\n| C2 | 0.1uF | 1 |\n| R1/R2 | 4.7k | 2 |\n| R3 | 15 (500mW) | 1|\n| D1 | BAT54H | 1|\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fchrisb2%2Fds3231-breakout","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fchrisb2%2Fds3231-breakout","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fchrisb2%2Fds3231-breakout/lists"}