{"id":8045,"date":"2026-06-28T08:48:09","date_gmt":"2026-06-28T08:48:09","guid":{"rendered":"https:\/\/materialparts.com\/mcp7940n-i-sn\/"},"modified":"2026-06-28T11:35:29","modified_gmt":"2026-06-28T11:35:29","slug":"mcp7940n-i-sn","status":"publish","type":"post","link":"https:\/\/materialparts.com\/zh\/mcp7940n-i-sn\/","title":{"rendered":"MCP7940N-I\/SN"},"content":{"rendered":"<h2>MCP7940N-I\/SN Overview<\/h2>\n<p>The MCP7940N-I\/SN is a battery-backed I2C real-time clock from Microchip integrating 64 bytes SRAM and 128 bytes EEPROM, with only 1.2uA timekeeping current, dual alarm outputs, in an SOIC-8 package.<\/p>\n<h3>\u4e3b\u8981\u529f\u80fd<\/h3>\n<ul>\n<li>I2C interface (400kHz)<\/li>\n<li>Supply voltage: 1.8V-5.5V<\/li>\n<li>Timekeeping current: 1.2uA<\/li>\n<li>64 bytes SRAM<\/li>\n<li>128 bytes EEPROM<\/li>\n<li>Dual alarm function<\/li>\n<li>External 32.768kHz crystal<\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>MCP7940N-I\/SN Overview The MCP7940N-I\/SN is a battery-backed I2C real-time clock from Microchip integrating 64 bytes SRAM and 128 bytes EEPROM, with only 1.2uA timekeeping current, dual alarm outputs, in an SOIC-8 package. Key Features I2C interface (400kHz) Supply voltage: 1.8V-5.5V Timekeeping current: 1.2uA 64 bytes SRAM 128 bytes EEPROM Dual alarm function External 32.768kHz crystal<\/p>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,55],"tags":[],"chip_brand":[134],"class_list":["post-8045","post","type-post","status-publish","format-standard","hentry","category-integrated-circuits-ics","category-transistors","chip_brand-microchip"],"acf":{"brief_explanation":"RTC with SRAM and EEPROM, I2C, SOIC-8","date_code":"","package_case":"SOIC-8 (5.23 x 5.36 x 1.75 mm)","in_stock":13492,"datasheet":"https:\/\/ww1.microchip.com\/downloads\/en\/DeviceDoc\/20005010F.pdf","price":"$0.85 @ 1ku","product_introduction":"The MCP7940N-I\/SN is a battery-backed I2C real-time clock\/calendar (RTCC) with 64 bytes of SRAM from Microchip Technology, housed in an 8-pin SOIC package. It tracks time using internal counters for seconds, minutes, hours, days, months, years, and day-of-week with automatic leap year compensation through 2399. The device features dual programmable alarms, on-chip digital trimming with 1 PPM resolution and plus or minus 129 PPM range, and a multifunction output pin configurable as clock output, alarm output, or general-purpose output. Operating from 1.8 V to 5.5 V with I2C speeds up to 400 kHz, it achieves AEC-Q100 qualification for automotive applications.","working_principle":"The MCP7940N-I\/SN uses a 32.768 kHz tuning fork crystal as the timebase, divided down by internal counters to generate seconds, minutes, hours, days, months, and years. The I2C serial interface allows a host microcontroller to read and write the timekeeping registers and configure alarm functions. The digital trimming circuit adjusts the crystal oscillator frequency in 1 PPM steps by periodically adding or omitting oscillator cycles, compensating for crystal tolerance and temperature drift. When VCC drops below the switchover threshold, the power-sense circuit automatically switches to the backup battery supply (VBAT, minimum 1.3 V), ensuring continuous timekeeping and SRAM data retention. The alarm registers compare user-programmed values against the current time; upon match, the multifunction output pin asserts and the alarm flag is set in the status register. The CLKOUT pin can output programmable frequencies of 32.768 kHz, 8.192 kHz, 4.096 kHz, or 1 Hz derived from the crystal oscillator.","pin_description":"<table><tr><th>Pin<\/th><th>Name<\/th><th>Description<\/th><\/tr><tr><td>1<\/td><td>X1<\/td><td>Crystal oscillator input; connect 32.768 kHz crystal<\/td><\/tr><tr><td>2<\/td><td>X2<\/td><td>Crystal oscillator output; connect 32.768 kHz crystal<\/td><\/tr><tr><td>3<\/td><td>VBAT<\/td><td>Battery backup input (1.3 V to 5.5 V); powers timekeeping and SRAM when VCC is absent<\/td><\/tr><tr><td>4<\/td><td>VSS<\/td><td>Ground<\/td><\/tr><tr><td>5<\/td><td>SDA<\/td><td>I2C serial data; open-drain, requires external pull-up resistor<\/td><\/tr><tr><td>6<\/td><td>SCL<\/td><td>I2C serial clock; open-drain, requires external pull-up resistor<\/td><\/tr><tr><td>7<\/td><td>MFP<\/td><td>Multi-function output; configurable as alarm output, clock output, or general-purpose output<\/td><\/tr><tr><td>8<\/td><td>VCC<\/td><td>Main power supply (1.8 V to 5.5 V)<\/td><\/tr><\/table>","application_scenarios":"<ul><li><strong>Automotive Real-Time Clock<\/strong>: AEC-Q100 qualified timekeeping for infotainment and body control modules<\/li><li><strong>Industrial Data Logging<\/strong>: Timestamping events and sensor readings in battery-backed measurement systems<\/li><li><strong>Embedded System Wake-Up<\/strong>: Alarm-triggered microcontroller wake from sleep mode for periodic tasks<\/li><li><strong>Power Management<\/strong>: Time-stamped power-fail detection with automatic battery switchover logging<\/li><li><strong>Consumer Electronics<\/strong>: Calendar and alarm functions in smart meters, thermostats, and appliances<\/li><\/ul>","alternative_models":"<table><tr><th>Model<\/th><th>Manufacturer<\/th><th>Interface<\/th><th>SRAM<\/th><th>Trimming<\/th><th>Package<\/th><\/tr><tr><td>MCP7940NT-I\/SN<\/td><td>Microchip<\/td><td>I2C<\/td><td>64 B<\/td><td>Digital<\/td><td>SOIC-8<\/td><\/tr><tr><td>MCP79412-I\/SN<\/td><td>Microchip<\/td><td>I2C<\/td><td>64 B + EEPROM<\/td><td>Digital<\/td><td>SOIC-8<\/td><\/tr><tr><td>DS3231SN<\/td><td>Maxim\/ADI<\/td><td>I2C<\/td><td>236 B<\/td><td>TCXO<\/td><td>SOIC-16<\/td><\/tr><tr><td>PCF8563BS<\/td><td>NXP<\/td><td>I2C<\/td><td>0<\/td><td>No<\/td><td>TSSOP-8<\/td><\/tr><tr><td>RV-8803-C7<\/td><td>Micro Crystal<\/td><td>I2C<\/td><td>0<\/td><td>No<\/td><td>DFN-8<\/td><\/tr><\/table>\n<p>MCP7940N-I\/SN is a battery-backed I2C RTC from Microchip in 8-SOIC with 64-byte SRAM and digital trimming. The MCP7940NT-I\/SN variant includes a temperature-compensated crystal oscillator option. MCP7940M-I\/SN omits the SRAM for lower cost. DS1307Z from Maxim\/ADI is the industry-standard alternative RTC without battery backup. For higher accuracy, DS3231 provides \u00b12ppm TCXO-based RTC with integrated crystal in SOIC-16.<\/p>"},"_links":{"self":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/8045","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/comments?post=8045"}],"version-history":[{"count":1,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/8045\/revisions"}],"predecessor-version":[{"id":8086,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/posts\/8045\/revisions\/8086"}],"wp:attachment":[{"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/media?parent=8045"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/categories?post=8045"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/tags?post=8045"},{"taxonomy":"chip_brand","embeddable":true,"href":"https:\/\/materialparts.com\/zh\/wp-json\/wp\/v2\/chip_brand?post=8045"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}