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Analog Devices Inc./Maxim Integrated MAX6421US26-T
- Part No.:
- MAX6421US26-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX6421US26-T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT143-4
- Quantity:
- Payment:
- Shipping:
Inventory:3,035
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Product details
Overview
MAX6421US26-T from Maxim Integrated is a low-power microprocessor reset supervisor IC in SOT143-4 package, featuring active-low push-pull RESET output, 2.625V ±2.5% factory-trimmed reset threshold, capacitor-adjustable reset timeout (275µs to >100ms), and guaranteed operation down to VCC = 1V. It monitors system supply voltage during power-up, brownout, and power-down in portable battery-powered controllers.
For engineers reviewing the MAX6421US26-T datasheet, MAX6421US26-T pinout, MAX6421US26-T application, or MAX6421US26-T equivalent, key selection criteria include reset threshold accuracy, quiescent current (1.6µA typ), SRT capacitor-based timeout flexibility, push-pull drive capability, and SOT143-4 footprint compatibility with space-constrained embedded designs.
Technical Context
The MAX6421US26-T implements a precision bandgap-based voltage detector with 2.5% threshold tolerance over –40°C to +125°C and 4mV hysteresis. Its internal 240nA current source charges an external capacitor on the SRT pin to generate a programmable reset timeout period governed by tRP = 2.73×10⁶ × CSRT + 275µs.
It asserts RESET low when VCC falls below 2.625V and holds it low for the full timeout after VCC rises above threshold. The push-pull output delivers VOL ≤ 0.4V at 3.2mA sink and VOH ≥ 0.8×VCC at 800µA source, ensuring robust logic-level compatibility with µP reset inputs across 1.6V–5V supply ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V ±2.5% - factory-laser-trimmed value enabling precise brownout detection at nominal 2.625V supply level |
| Quiescent Current | 1.6µA typical - enables multi-year battery life in always-on monitoring applications |
| Reset Timeout Range | 275µs to >100ms - set externally via 0–15nF capacitor on SRT pin, supporting µP initialization timing requirements |
| VCC Operating Range | 1.0V to 5.5V - guarantees valid RESET assertion even during deep brownout down to 1V supply |
| Output Type | Active-low push-pull - eliminates need for external pullup resistor and drives µP reset input directly |
| Temperature Range | –40°C to +125°C - qualified for automotive, industrial, and medical environments requiring extended thermal stability |
| VCC to RESET Delay | 80µs - ensures fast response to supply droop, critical for preventing code corruption during transient faults |
Pinout & Package
MAX6421US26-T is housed in a 4-pin SOT143-4 surface-mount package (outline 21-0052), measuring 2.1mm × 2.3mm × 0.95mm, with gull-wing leads and RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - GND | Ground reference | Return path for internal circuitry and SRT ramp current; must be low-impedance connection to system ground plane |
| 2 - VCC | Supply and threshold monitor input | Monitored voltage rail; device asserts RESET when this pin falls below 2.625V; operates down to 1.0V |
| 3 - RESET | Active-low push-pull reset output | Drives µP reset input low during fault; sinks up to 3.2mA or sources up to 800µA; no external pullup required |
| 4 - SRT | Set Reset Timeout input | Connects to external timing capacitor; internal 240nA current source charges CSRT to determine timeout duration |
Key Features
| Feature | Design Value |
|---|---|
| Capacitor-adjustable reset timeout | Enables precise timing alignment with µP boot sequence using standard ceramic capacitors (0–15nF), avoiding fixed-delay limitations |
| Guaranteed reset validity to VCC = 1V | Ensures deterministic reset behavior during severe brownout, preventing undefined µP states when supply collapses |
| Immunity to short VCC transients | Rejects glitches ≤50µs wide when VCC dips 100mV below threshold, eliminating false resets from switching noise or ESD |
| Low quiescent current (1.6µA) | Minimizes battery drain in always-connected IoT sensors and portable medical devices operating for years on coin cells |
| Factory-trimmed reset threshold | 2.625V ±2.5% tolerance eliminates manual calibration and reduces BOM count versus resistor-divider solutions |
Applications
| Battery-Powered Portable Controllers | Automotive Body Control Modules |
|---|---|
|
Use Scenario: A handheld diagnostic tool powered by a single Li-ion cell (2.8V–4.2V) requires reliable reset during battery voltage sag. IC Role / Device Role / Timing Role: MAX6421US26-T monitors VCC and asserts active-low RESET to ARM Cortex-M0 controller when voltage drops below 2.625V. Use Value: Prevents firmware lockup during intermittent battery contact loss, with 1.6µA quiescent current extending operational runtime between charges. |
Use Scenario: A door module MCU must survive cold-cranking events where battery voltage dips to 2.5V for 50ms. IC Role / Device Role / Timing Role: MAX6421US26-T detects 2.625V threshold breach and holds reset for 50ms minimum via 15nF SRT capacitor. Use Value: Ensures deterministic restart after cranking transient, with –40°C to +125°C rating matching under-hood thermal requirements. |
| Medical Infusion Pump Controllers | Industrial PLC I/O Modules |
|
Use Scenario: An infusion pump uses a low-power MCU that must not execute erratic commands during AC/DC adapter brownout. IC Role / Device Role / Timing Role: MAX6421US26-T provides fail-safe reset supervision with 275µs minimum timeout, synchronized to pump motor startup delay. Use Value: Guarantees safe shutdown and restart sequence; 2.5% threshold accuracy prevents premature or delayed reset assertion affecting dose delivery. |
Use Scenario: A DIN-rail mounted I/O module experiences 12V supply ripple from nearby motor drives. IC Role / Device Role / Timing Role: MAX6421US26-T supervises the 3.3V LDO output feeding its FPGA configuration controller. Use Value: Push-pull RESET output drives FPGA PROG_B pin directly without pullup, reducing component count and board area in dense industrial layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor reset supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6421XS26-T | Same electrical specs and reset threshold, but in SC70-4 package (2.0mm × 2.1mm); 0.5mm pitch vs. SOT143's 0.65mm | Preferred for ultra-dense PCBs where 0.1mm smaller footprint and finer pitch are critical | Select MAX6421XS26-T only if layout allows SC70-4 reflow profile and trace routing constraints |
| TLV803EC26DBZR | Fixed 2.63V threshold, 200ms min timeout (non-adjustable), 0.5µA IQ, SOT23-3 package | Suitable for cost-sensitive, low-complexity systems where timeout flexibility is unnecessary | Choose TLV803EC26DBZR when design prioritizes lowest possible quiescent current and simplified BOM over timeout tuning |
Compared with MAX6421US26-T, MAX6421XS26-T offers identical functionality in a marginally smaller package but requires tighter assembly control, while TLV803EC26DBZR trades timeout adjustability and push-pull drive for ultra-low IQ and reduced pin count-making it viable only where those specific trade-offs align with system requirements.
Availability
MAX6421US26-T is available at Aetrix Electronics and suitable for battery-powered portable controllers, automotive body electronics, and medical infusion pump systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX6421US26-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and computing applications.
The MAX6421 series belongs to Maxim's microprocessor supervisor product line, designed specifically to provide reliable, low-power, and configurable reset supervision for resource-constrained embedded systems operating under variable supply conditions.
FAQ
What is the exact reset threshold voltage of the MAX6421US26-T?
The MAX6421US26-T has a factory-laser-trimmed reset threshold of 2.625V, with guaranteed accuracy of ±2.5% over the full –40°C to +125°C temperature range. This value is confirmed in Table 1 of the datasheet, where suffix "26" explicitly maps to 2.625V nominal, and Electrical Characteristics specify VTH = VTH ±2.5% at TA = –40°C to +125°C.
Does the MAX6421US26-T require an external pullup resistor on the RESET pin?
No, the MAX6421US26-T features an active-low push-pull RESET output, meaning it actively drives both high and low states without needing an external pullup. The datasheet specifies VOH ≥ 0.8×VCC at 800µA source and VOL ≤ 0.4V at 3.2mA sink, confirming full rail-to-rail drive capability - a key differentiator from open-drain variants like MAX6423US26-T.
How is the reset timeout period set for the MAX6421US26-T?
The reset timeout period for MAX6421US26-T is set by connecting an external capacitor (CSRT) between the SRT pin and GND. The relationship is defined as tRP = 2.73×10⁶ × CSRT + 275µs, where tRP is in seconds and CSRT in farads. For example, a 1500pF capacitor yields ~4.375ms timeout, as shown in Typical Operating Characteristics figure toc02.
Can the MAX6421US26-T operate reliably during cold-cranking in automotive applications?
Yes, the MAX6421US26-T is rated for –40°C to +125°C operation and guarantees valid RESET assertion down to VCC = 1V. Its immunity to short VCC transients (e.g., rejecting ≤50µs glitches at 100mV overdrive) makes it suitable for cold-cranking scenarios where battery voltage may dip to ~2.5V for tens of milliseconds - well within its functional window.
What package type does the MAX6421US26-T use, and is it RoHS compliant?
The MAX6421US26-T uses the 4-pin SOT143-4 package (outline 21-0052), with dimensions 2.1mm × 2.3mm × 0.95mm and 0.65mm lead pitch. Per Maxim's Package Information section, the "-T" suffix denotes lead-free RoHS-compliant packaging, and the device meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) requirements.
MAX6421US26-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- TO-253-4, TO-253AA
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.625V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- Adjustable/Selectable
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-4
MAX6421US26-T FAQ
1.How can I place an order for MAX6421US26-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6421US26-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX6421US26-T reliable?
The price and inventory of MAX6421US26-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6421US26-T is usually 5 days.
3.What payment methods are accepted for MAX6421US26-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6421US26-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6421US26-T?
MAX6421US26-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6421US26-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX6421US26-T?
For technical support, including MAX6421US26-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6421US26-T requirements.
6.How does Aetrix verify that MAX6421US26-T is sourced from the original manufacturer or authorized distributors?
All MAX6421US26-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX6421US26-T meets industry standards.
7.What is the process for return or replacement of MAX6421US26-T?
All MAX6421US26-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6421US26-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX6421US26-T part is unused and in its original packaging.
Return procedure for MAX6421US26-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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