{"product_id":"hfd4-3-s-relay-module-3-3-5v-stm32-51-microcontroller","title":"HFD4\/3-S Relay Module 3.3–5V for STM32 \u0026 51 Microcontrollers","description":"\n\u003ch2\u003eHFD4\/3-S Thin Relay Module – 3.3V to 5V, STM32 \u0026amp; 51 MCU Compatible\u003c\/h2\u003e\n\n\u003cp\u003eTake precise control of your electronics projects with this compact \u003cstrong\u003eHFD4\/3-S Relay Module\u003c\/strong\u003e. Designed for compatibility with STM32, 51 series, and other popular microcontrollers, this slim relay module bridges the gap between low-voltage control signals and real-world switching tasks — perfect for hobbyists, engineers, and makers alike.\u003c\/p\u003e\n\n\u003cp\u003eMade in Mainland China.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWide Supply Voltage:\u003c\/strong\u003e Operates across a broad 3.3V–6V range, making it compatible with 3.3V (STM32, ESP32) and 5V (Arduino, 51 MCU) systems without extra circuitry.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigh-Level Trigger:\u003c\/strong\u003e Triggered by a high logic level (\u0026gt;1.3V), with low trigger current of just 1.8mA — easy on your microcontroller's GPIO pins.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLow Standby Power:\u003c\/strong\u003e Quiescent current of only 5µA keeps your overall system power consumption minimal.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSignal Switching Ready:\u003c\/strong\u003e Signal insertion loss \u0026lt;0.3dB @ 1KHz makes it ideal for clean signal routing and switching applications.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMaximum Load Capacity:\u003c\/strong\u003e Handles up to 2A @ 30VDC and 0.5A @ 220VAC — suitable for both signal switching and small-load power control.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact \u0026amp; Thin Form Factor:\u003c\/strong\u003e The slim HFD4\/3-S design saves precious board space in tight enclosures or project boxes.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSafety Note:\u003c\/strong\u003e For loads exceeding 60V, we strongly recommend using an insulation protection enclosure to prevent accidental contact.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSupply Voltage (VCC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3.3V – 6V\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eQuiescent Current\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e5µA\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAction Current\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e40mA\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eTrigger Mode\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eHigh Level (IO)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eHigh Trigger Level\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;1.3V and \u0026lt;VCC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eLow Level Threshold\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u0026lt;0.5V\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eTrigger Current\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1.8mA\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMax Load (DC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e2A @ 30VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMax Load (AC)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.5A @ 220VAC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSignal Insertion Loss\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u0026lt;0.3dB @ 1KHz\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCondition\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eNew\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePackage Quantity\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1 Piece\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eIdeal Use Cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eMicrocontroller-driven automation and switching circuits\u003c\/li\u003e\n  \u003cli\u003eSignal routing and on\/off control in embedded systems\u003c\/li\u003e\n  \u003cli\u003eSmart home DIY projects with STM32, ESP32, or Arduino\u003c\/li\u003e\n  \u003cli\u003eLow-power IoT device control and prototyping\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eRelated Products You May Like\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/10pcs-2-pin-quick-splice-spring-wire-connectors-lock-terminals\"\u003e10pcs 2-Pin Spring Wire Connectors – Quick Splice Lock Terminals\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/12pcs-16mm-momentary-push-button-switch-1no-metal-2-pin-self-reset\"\u003e12pcs 16mm Momentary Push Button Switch 1NO Metal 2-Pin Self-Reset\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/stainless-steel-self-tapping-screws-m2-2-m4-8-phillips-wood-hinge\"\u003e10PCS Stainless Steel Self-Tapping Screws M2.2–M4.8 Phillips\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eNote: Please allow 2%–3% dimensional tolerance due to manual measurement. Product color may vary slightly from images due to monitor calibration differences.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.epa.gov\/recycle\/used-lithium-ion-batteries\" target=\"_blank\" rel=\"noopener\"\u003eEPA guidance on lithium-ion battery handling\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\n\u003ch4\u003eQ: Is this relay module compatible with 3.3V microcontrollers like STM32 or ESP32?\u003c\/h4\u003e\n\u003cp\u003eA: Yes! The HFD4\/3-S relay module supports a wide supply voltage range of 3.3V to 6V, making it fully compatible with 3.3V microcontrollers such as STM32 and ESP32, as well as 5V systems like Arduino and 51-series MCUs — no level shifter required.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What is the maximum switching load this relay module can handle?\u003c\/h4\u003e\n\u003cp\u003eA: This relay module can switch up to 2A at 30VDC or 0.5A at 220VAC. For any load voltage exceeding 60V, it is strongly recommended to place the module inside an insulation protection enclosure to ensure safe operation.\u003c\/p\u003e\n\n\u003ch4\u003eQ: How much current does the GPIO pin need to provide to trigger the relay?\u003c\/h4\u003e\n\u003cp\u003eA: The relay requires a trigger current of just 1.8mA from the IO pin, and a high logic level greater than 1.3V (but below VCC). This is well within the output capability of virtually all modern microcontroller GPIO pins, so no additional driver transistor is needed in most cases.\u003c\/p\u003e\n\n\u003ch4\u003eQ: How many relay modules are included in one purchase?\u003c\/h4\u003e\n\u003cp\u003eA: Each order includes 1 piece of the HFD4\/3-S relay module.\u003c\/p\u003e\n\u003c!-- production-packaging-notice --\u003e\n\u003ch3\u003eProduction \u0026amp; Packaging Notice\u003c\/h3\u003e\n\u003cp\u003eTo maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Is this relay module compatible with 3.3V microcontrollers like STM32 or ESP32?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes! The HFD4\/3-S relay module supports a wide supply voltage range of 3.3V to 6V, making it fully compatible with 3.3V microcontrollers such as STM32 and ESP32, as well as 5V systems like Arduino and 51-series MCUs — no level shifter required.\"}}, {\"@type\": \"Question\", \"name\": \"What is the maximum switching load this relay module can handle?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"This relay module can switch up to 2A at 30VDC or 0.5A at 220VAC. For any load voltage exceeding 60V, it is strongly recommended to place the module inside an insulation protection enclosure to ensure safe operation.\"}}, {\"@type\": \"Question\", \"name\": \"How much current does the GPIO pin need to provide to trigger the relay?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The relay requires a trigger current of just 1.8mA from the IO pin, and a high logic level greater than 1.3V (but below VCC). This is well within the output capability of virtually all modern microcontroller GPIO pins, so no additional driver transistor is needed in most cases.\"}}, {\"@type\": \"Question\", \"name\": \"How many relay modules are included in one purchase?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Each order includes 1 piece of the HFD4\/3-S relay module.\"}}]}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"BreadcrumbList\", \"itemListElement\": [{\"@type\": \"ListItem\", \"position\": 1, \"name\": \"Home\", \"item\": \"https:\/\/68k0rh-yt.myshopify.com\/\"}, {\"@type\": \"ListItem\", \"position\": 2, \"name\": \"Home page\", \"item\": \"https:\/\/68k0rh-yt.myshopify.com\/collections\/frontpage\"}, {\"@type\": \"ListItem\", \"position\": 3, \"name\": \"HFD4\/3-S Relay Module 3.3–5V for STM32 \u0026 51 Microcontrollers\", \"item\": \"https:\/\/68k0rh-yt.myshopify.com\/products\/hfd4-3-s-relay-module-3-3-5v-stm32-51-microcontroller\"}]}\u003c\/script\u003e","brand":"Richie's","offers":[{"title":"as pic","offer_id":57573792874662,"sku":"1005012749039496-as pic","price":21.75,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0785\/2182\/7494\/files\/S636063cfea714d819d8145bea325c1c5A_0b66c134-b45f-4548-a677-f9409588051a.webp?v=1791233939","url":"https:\/\/richiesmart.com\/products\/hfd4-3-s-relay-module-3-3-5v-stm32-51-microcontroller","provider":"Richie's","version":"1.0","type":"link"}