MCP121T-315E/TT Microchip Voltage Supervisor IC, SOT-23-3 - Full Reel of 3,000

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Overview MCP121T-315E/TT from Microchip Technology is a low-power microcontroller supervisory circuit for monitoring a single supply rail and holding a processor or logic circuit i n reset during power-up, power-down, and brownout events. It is supplied in a compact SOT-23-3 surface-mount package for dense embedded and control-board designs. This supervisor is used when a design needs a dedicated reset monitor rather than relying only on controller start-up behavior. The MCP121T-315E/TT provides an active-low RESET output with an open-drain/open-collector style output stage and a reset threshold listed by DigiKey as 3.075 V. When the monitored supply falls below the reset threshold, the RESET output asserts low; after the supply recovers, the reset signal remains asserted for the reset timeout period before releasing the downstream device. Package Sale Basis Sales Unit One full reel Components Per Sales Unit 3,000 pieces Order Quantity 1 Includes 1 reel containing 3,000 MCP121T-315E/TT components Inventory Packaging Marking 3000/REEL Component Package SOT-23-3 surface-mount package This product is structured for full-reel purchasing and production handling. Order quantity 1 corresponds to one complete reel containing 3,000 components. This format is intended for SMT assembly, feeder setup, production kitting, and controlled material replenishment. Key Benefits Dedicated supply supervision helps keep controllers and digital logic in a predictable reset state during unstable power conditions. Full-reel format supports automated assembly and production material handling. Compact SOT-23-3 package fits space-constrained embedded hardware. Active-low push-pull reset output can directly drive many reset inputs without an external pull-up in suitable designs. Low supply-current supervisor family is well suited for embedded, portable, and industrial control circuits. Extended temperature range supports common commercial and industrial electronic assemblies. Product Features Manufacturer part number: MCP121T-315E/TT. Manufacturer: Microchip Technology. Function: simple reset / power-on reset supervisor. Monitors one supply voltage rail. Reset output: active low. Output type: open-drain / open-collector. Reset timeout listed by DigiKey as 150 ms minimum. No manual reset input on this listed variant. Supplied as full reel tape-and-reel packaging for SOT-23-3 assembly. Technical Specifications Parameter Value Part Number MCP121T-315E/TT Manufacturer Microchip Technology Product Category Integrated Circuits (ICs), Power Management (PMIC), Supervisors Sales Package Full reel Components Per Package 3,000 Supervisor Type Simple reset / power-on reset Number of Voltages Monitored 1 Reset Threshold Voltage 3.075 V distributor-listed threshold Reset Output Active low Output Topology Push-pull / totem pole Reset Timeout 150 ms minimum Operating Temperature -40 C to +125 C (TA) Mounting Type Surface mount Package / Case TO-236-3, SC-59, SOT-23-3 Supplier Device Package SOT-23-3 Packaging Tape and reel, full reel sales unit Base Product Number MCP121 Design and Selection Notes The MCP121T-315E/TT should be selected when the monitored rail, reset threshold, reset polarity, output topology, and reset timeout match the target controller or logic reset requirements. In a typical circuit, the supervisor monitors the supply rail and holds the downstream reset input low when the rail is below the reset threshold or not yet stable. Because this variant uses an active-low open-drain/open-collector reset output, substitution should be checked carefully. Push-pull reset outputs actively drive both high and low states, while open-drain reset outputs depend on an external pull-up and may be used differently in multi-source reset networks. Confirm pinout, package, reset threshold, output behavior, and timing against the datasheet before design release or replacement approval. The part is listed by DigiKey as active, but lifecycle and recommended alternatives can change. Buyers and engineers should confirm the latest Microchip documentation and distributor parametric information during qualification. Applications Microcontroller, microprocessor, DSP, and embedded controller reset supervision. Power-on reset and brownout protection for low-voltage digital rails. Industrial control boards, sensor modules, and automation electronics. Consumer, portable, and battery-powered embedded systems. Communication, security, and networking support circuitry. Production builds that require full-reel SOT-23-3 material for SMT assembly. Repair, replacement, and controlled continuation builds where MCP121T-315E/TT is specified. Sourcing and Documentation Notes Please review the attached Product Specification PDF before purchase or design use. The datasheet is the controlling source for electrical limits, reset timing, threshold behavior, pin configuration, package dimensions, ordering information, and absolute maximum ratings. This listing is arranged for full-reel purchasing. Buyers should confirm the reel size, package/case, reset threshold, output polarity, output topology, date-code needs, and approved manufacturer part number before using this component in a qualified build or approved vendor list. FAQ What is MCP121T-315E/TT best suited for? MCP121T-315E/TT is best suited for microcontroller and processor boards that need a simple power-on reset or brownout supervisor for one supply rail. What reset threshold should be checked? The 315 ordering code is used for the approximately 3.08 V reset-threshold option. Confirm the exact threshold limits and temperature conditions in the Microchip datasheet before design release. Is the reset output active-low? Yes. The MCP121 family uses an active-low reset output, which keeps the downstream controller in reset while the monitored supply is below the trip point. Is MCP121T-315E/TT open-drain or push-pull? Treat this MCP121 orderable part as an active-low open-drain/open-collector supervisor. Make sure the reset net has the correct pull-up strategy and that any shared reset sources are compatible. How long does reset stay asserted after power recovers? The reset delay must be checked from the datasheet and exact distributor listing for the orderable suffix. Use the guaranteed timing limits, not only a typical value, when validating startup behavior. What does order quantity 1 include? Order quantity 1 means one full reel containing 3,000 MCP121T-315E/TT components. Can MCP121T-315E/TT replace another supervisor? Only after matching threshold voltage, reset polarity, output topology, reset delay, package, pinout, operating voltage, temperature grade, and system pull-up requirements. When would this part be a poor fit? It is not the right choice if the circuit needs multiple monitored rails, a watchdog timer, a manual-reset input, or a push-pull reset output without redesigning the reset network. What application issue does it help prevent? It helps prevent code execution during undervoltage or unstable supply conditions, where RAM contents, peripheral states, or processor startup can become unreliable. Where can I find the datasheet? Use the attached Product Specification PDF for MCP102/MCP103/MCP121/MCP131 electrical characteristics, timing, package, and application guidance. Show more