MCP121T-450E/TT Microchip Integrated Circuit (Other) In Stock
The MCP121T-450E/TT is a single-channel voltage supervisor and microprocessor reset IC from Microchip, with a fixed threshold window of 4.271 V to 4.49 V, housed in a compact 3-pin SOT-23 package. It monitors supply voltage and asserts a reset signal when the voltage falls below the threshold, ensuring reliable processor startup. Ideal for 5 V microcontroller systems, embedded controllers, and consumer electronics requiring robust power-on reset and brownout detection.
- Manufacturer
- Microchip
- Package
- Other
- Pin Count
- 3
- Lifecycle
- ACTIVE
- Datasheet
- MCP121T-450E/TT Datasheet PDF
- Category
- Integrated Circuit
- Price
- From $0.2450(MOQ 1)
- Temp Range
- -40.0°C to 125.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Single-channel voltage supervisor with fixed threshold: 4.271 V to 4.49 V for 5 V system monitoring
- Active-low open-drain reset output for direct connection to microcontroller reset pins
- Tiny 3-pin SOT-23 package for minimal PCB space in space-constrained designs
- Very low quiescent current for battery-backed and low-power system designs
- No external components required — fixed threshold set internally
- RoHS and lead-free compliant (JESD-609 e3)
Applications
MCP121T-450E/TT is used in embedded systems, industrial controllers, and consumer electronics where a reliable power-on reset and brownout detection circuit is needed for 5 V microprocessors. It ensures that the processor remains in reset during power-up ramp and brownout conditions, preventing unpredictable system behavior in products such as PLCs, smart home devices, and battery-backed embedded controllers.
Specifications
| Pbfree Code | Yes |
| Manufacturer Package Code | SOT-23-3 |
| Factory Lead Time | 6Weeks |
| YTEOL | 9 |
| Additional Feature | BAT BUP SW:N;MNL RST:N;OV DET:N;PW FL IP:N;PW FL IO:N;PW FL OP:N;PRG RST DLY:N;UV DET:N;WD:N;WWD:N |
| Adjustable Threshold | NO |
| Analog IC - Other Type | VOLTAGE SUPERVISOR/RESET IC |
| JESD-30 Code | R-PDSO-G3 |
| JESD-609 Code | e3 |
| Number of Channels | 1 |
| Number of Functions | 1 |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | TO-236 |
| Package Shape | RECTANGULAR |
| Package Style | SMALL OUTLINE, THIN PROFILE |
| Peak Reflow Temperature (Cel) | 260 |
| Qualification Status | Not Qualified |
| Screening Level | TS 16949 |
| Supply Current-Max (Isup) | 0.02mA |
| Supply Voltage-Max (Vsup) | 5.5V |
| Supply Voltage-Min (Vsup) | 1V |
| Supply Voltage-Nom (Vsup) | 3V |
| Surface Mount | YES |
| Temperature Grade | AUTOMOTIVE |
| Terminal Finish | Matte Tin (Sn) |
| Terminal Form | GULL WING |
| Terminal Pitch | 0.95mm |
| Terminal Position | DUAL |
| Threshold Voltage-Nom | +4.38V |
| Time@Peak Reflow Temperature-Max (s) | 40 |
| Package | Other |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 1 |
| ECCN | EAR99 |
| HTS Code | 8542.39.00.01 |
| Country of Origin | Thailand |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
What is the threshold voltage window of MCP121T-450E/TT, and which supply voltage systems does it monitor?
MCP121T-450E/TT has a fixed supervisory threshold window of 4.271 V minimum to 4.49 V maximum, making it specifically designed to monitor a 5 V supply rail in microprocessor and microcontroller systems. When the supply drops below this window, the device asserts the active-low reset output, holding the processor in reset until the supply recovers and stabilizes.
Does MCP121T-450E/TT require any external components to function as a microcontroller reset supervisor?
No, MCP121T-450E/TT requires no external resistors, capacitors, or reference components — the threshold is set internally at 4.271 V to 4.49 V. This simplifies the power management circuit to just 3 pins: VCC, GND, and RESET, reducing BOM cost and minimizing PCB area to a single 3-pin SOT-23 device.
How does MCP121T-450E/TT protect a 5 V embedded system during a brownout condition?
During a brownout, when the 5 V supply dips below 4.271 V, MCP121T-450E/TT drives its active-low open-drain reset output low, holding the microcontroller in reset. This prevents the processor from executing invalid instructions or corrupting EEPROM and Flash data during the undervoltage period. The reset is released only after the supply returns above the 4.49 V threshold.
What is the package and footprint of MCP121T-450E/TT, and is it compatible with automated SMT assembly?
MCP121T-450E/TT uses a 3-pin SOT-23 (JEDEC TO-236) surface-mount package with a body of approximately 1.3 mm x 2.9 mm. The package is fully compatible with standard SMT pick-and-place and reflow assembly processes, and its small footprint makes it suitable for tight PCB designs where a dedicated reset supervisor must fit alongside the microcontroller and decoupling components.
Is MCP121T-450E/TT available in other threshold voltage options, and how does it compare to MCP121T-300 for 3.3 V system designs?
Yes, the MCP121T family is available in multiple fixed threshold options. MCP121T-300 monitors a 3 V threshold window suitable for 3.3 V supply rails, while MCP121T-450E/TT targets 5 V supplies with its 4.271 V to 4.49 V window. Both variants share the same 3-pin SOT-23 package and open-drain output, so switching between them requires only a part number change with no PCB modification.
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| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 1+ | $0.5300 | $0.53 |
| 100+ | $0.4000 | $40.00 |
| 1000+ | $0.3300 | $330.00 |
| 1500+ | $0.3000 | $450.00 |
| 2250+ | $0.2800 | $630.00 |
| 3000+ | $0.2450 | $735.00 |
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