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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:2,000
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Product details
Overview
MAX6421US26+T from Analog Devices is a low-power microprocessor supervisor IC that monitors VCC supply voltage and asserts an active-low push-pull reset signal when voltage falls below 2.625V (±2.5% over temperature). It features capacitor-adjustable reset timeout (3.0–5.75ms with 1500pF), guaranteed operation down to VCC = 1V, and 1.6µA typical quiescent current. It is used in battery-powered controllers and portable equipment for reliable power-up/power-down sequencing.
For engineers reviewing the MAX6421US26+T datasheet, MAX6421US26+T pinout, MAX6421US26+T application, or MAX6421US26+T equivalent, key selection criteria include its 2.625V reset threshold accuracy, SC70-4/SOT143-4 package compatibility, push-pull output drive capability, and immunity to short VCC transients - all critical for embedded µP reset integrity in space-constrained designs.
Technical Context
The MAX6421US26+T implements a precision voltage detector with laser-trimmed internal resistors to set its 2.625V nominal reset threshold. Its reset assertion logic is triggered by VCC falling below VTH, with hysteresis of 4×VTH (≈10.5mV) to prevent chatter near threshold.
Reset deassertion is controlled by an internal 240nA current source charging an external capacitor (CSRT) on the SRT pin to a 0.65V ramp threshold; timeout is programmable from 275µs to >10ms. The push-pull RESET output drives high/low actively and remains valid for VCC ≥ 1.0V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V ±2.5% over -40°C to +125°C - ensures robust brownout detection across automotive/industrial temperature ranges |
| Quiescent Current | 1.6µA typical at VCC ≤ 2.0V - enables multi-year battery life in always-on monitoring applications |
| Reset Timeout Range | 275µs (CSRT = 0) to 5.75ms (CSRT = 1500pF) - supports µP reset timing requirements from fast-boot to safety-critical systems |
| VCC Operating Range | 1.0V to 5.5V - guarantees reset validity during deep brownout and allows use with 1.2V–5V logic domains |
| Output Type | Active-low push-pull - eliminates need for external pullup resistor and provides strong low/high drive (≤0.4V VOL, ≥0.8×VCC VOH) |
| VCC to Reset Delay | 80µs at 1mV/µs VCC fall rate - ensures timely response to rapid supply collapse without false triggering |
| Operating Temperature | -40°C to +125°C - qualified for under-hood automotive and industrial control environments |
Pinout & Package
MAX6421US26+T is housed in a 4-pin SOT143-4 package (package code U4+1), with 1.3mm × 0.8mm footprint and 0.95mm height. Pin 1 = VCC, Pin 2 = GND, Pin 3 = RESET, Pin 4 = SRT.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Supply voltage and reset threshold monitor input | Primary power rail connection; device monitors this node for undervoltage events and powers internal circuitry |
| GND | Ground reference | Analog and digital ground return path; required for accurate threshold sensing and stable ramp generation |
| RESET | Active-low push-pull reset output | Drives µP reset input low during fault; actively pulls high after timeout - no external pullup needed |
| SRT | Set reset timeout input | Connects to external timing capacitor; 240nA constant current charges CSRT to 0.65V to define timeout period |
Key Features
| Feature | Design Value |
|---|---|
| Capacitor-adjustable reset timeout | Enables precise tailoring of reset pulse width (275µs–10ms+) to match specific µP requirements without firmware changes |
| Guaranteed reset validity to VCC = 1V | Ensures deterministic reset behavior during deep brownout conditions where many supervisors fail silently |
| Immunity to short VCC transients | Rejects glitches ≤50µs duration when VCC dips 100mV below threshold - prevents spurious resets in noisy power environments |
| Laser-trimmed reset threshold | Delivers ±1.5% accuracy at +25°C and ±2.5% over full temperature range - eliminates need for system-level calibration |
| Low-leakage SRT pin interface | Minimizes timing error from PCB leakage; supports ceramic capacitors only - ensures predictable, repeatable timeout |
Applications
| Battery-Powered Portable Controllers | Automotive Body Control Modules |
|---|---|
Use Scenario: A handheld medical diagnostic device powered by a single Li-ion cell experiences gradual discharge and occasional load-induced voltage sag. IC Role / Device Role / Timing Role: MAX6421US26+T continuously monitors VCC and asserts RESET if voltage drops below 2.625V, preventing corrupted memory writes or erratic MCU execution during brownout. Use Value: With 1.6µA ICC and guaranteed operation down to VCC = 1V, it extends usable battery life while ensuring safe shutdown before data loss occurs. | Use Scenario: An automotive door module must survive cold-crank (VCC dip to 2.2V) and load-dump transients without unintended MCU reset. IC Role / Device Role / Timing Role: MAX6421US26+T detects true undervoltage (not transient noise) and holds RESET asserted for ≥3ms after recovery - meeting ISO 16750-2 cold-crank timing requirements. Use Value: Its 80µs VCC-to-reset delay and 50µs glitch immunity prevent nuisance resets during engine cranking, improving system reliability. |
| Industrial Sensor Node Controllers | Medical Infusion Pump Logic Supervision |
Use Scenario: A wireless sensor node operates intermittently on a supercapacitor backup supply, requiring clean power-up sequencing after energy harvesting recharge. IC Role / Device Role / Timing Role: MAX6421US26+T generates a fixed 4.375ms reset pulse (with 1500pF SRT cap) to hold the ARM Cortex-M0+ in reset until regulated 3.3V rail stabilizes. Use Value: Push-pull output eliminates external components; SC70-4 package fits within 2.5mm² PCB area - critical for miniaturized IoT edge nodes. | Use Scenario: A Class II medical infusion pump uses dual-redundant MCUs; each requires independent, fail-safe reset supervision compliant with IEC 62304. IC Role / Device Role / Timing Role: MAX6421US26+T provides deterministic reset assertion on VCC drop below 2.625V, with timeout long enough to ensure both MCUs initialize synchronously. Use Value: ±2.5% threshold accuracy over -40°C to +125°C and AEC-Q100-aligned qualification (via MAX6340UK31/V+T family heritage) support safety-critical certification evidence. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6421US26-T | Same electrical specs and pinout; leaded (Pb) packaging instead of lead-free (+T suffix) | Not RoHS-compliant; restricted for new designs in EU/China markets | Select only for legacy repair or non-RoHS production environments |
| NCP302LS26T1G | 2.63V threshold, 1.8µA ICC, open-drain output, SOT23-5 package - requires external pullup | Lower drive strength, different pinout (5-pin vs 4-pin), no SRT-programmable timeout - fixed 200ms timeout | Choose only if fixed timeout and open-drain interface are acceptable; not drop-in compatible |
Compared with MAX6421US26+T, the MAX6421US26-T offers identical performance but lacks RoHS compliance, while NCP302LS26T1G trades programmable timeout and push-pull drive for lower cost and wider availability - however, its fixed timeout and open-drain output require board redesign and additional BOM components.
Availability
MAX6421US26+T is available at Aetrix Electronics and suitable for battery-powered portable controllers, automotive body control modules, and industrial sensor node controllers 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
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The MAX6421US26+T belongs to the MAX6340/MAX6421–MAX6426 family of ultra-low-power microprocessor supervisors, designed specifically for reliable reset generation in space-constrained, battery-sensitive, and thermally demanding embedded systems.
FAQ
What is the exact reset threshold voltage of the MAX6421US26+T?
The MAX6421US26+T has a nominal reset threshold of 2.625V, with ±1.5% accuracy at +25°C and ±2.5% accuracy over the full operating temperature range of -40°C to +125°C. This value is laser-trimmed at wafer test and confirmed in the Electrical Characteristics table under VTH parameter. The '26' suffix in MAX6421US26+T directly encodes this 2.625V threshold per Table 1 in the datasheet.
Can the MAX6421US26+T operate with a 1.2V supply rail?
Yes, the MAX6421US26+T guarantees functional operation down to VCC = 1.0V, including valid RESET output assertion and deassertion. At 1.2V, it draws only ~1.6µA (typical), maintains 2.625V threshold detection, and delivers a clean push-pull reset signal - making it suitable for ultra-low-voltage applications such as energy-harvesting sensors where supply rails dip below 1.8V.
How do I calculate the SRT capacitor value for a 5ms reset timeout using the MAX6421US26+T?
Use the formula CSRT = (tRP − 275µs) / 2.735 × 10⁶, where tRP is in seconds. For 5ms (0.005s): CSRT = (0.005 − 0.000275) / 2,735,000 ≈ 1727pF. A standard 1800pF ceramic capacitor yields ~5.2ms timeout. The MAX6421US26+T's SRT pin requires low-leakage (<10nA) dielectric - X7R or C0G ceramics are recommended; avoid electrolytics or high-leakage types.
Is the MAX6421US26+T pin-compatible with other devices in the MAX6421–MAX6426 family?
No - the MAX6421US26+T uses a 4-pin SOT143-4 package, while MAX6424/MAX6425/MAX6426 variants use 5-pin SOT23-5 packages. Within the 4-pin group, MAX6421US26+T shares identical pinout with MAX6421US16+T, MAX6421US22+T, etc., but is not pin-compatible with MAX6422 (active-high output) or MAX6423 (open-drain output), despite same package. Always verify pin function mapping per the Pin Description table.
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 low and high states. Unlike open-drain supervisors (e.g., MAX6423), it does not require an external pullup resistor. This simplifies BOM, reduces board area, and improves rise/fall time consistency - especially beneficial in high-density portable designs where every component counts.
MAX6421US26+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- TO-253-4, TO-253AA
- Packaging:
- Tape & Reel (TR)
- 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-143-4
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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