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Analog Devices Inc./Maxim Integrated MAX6421US26
- Part No.:
- MAX6421US26
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX6421US26.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT143-4
- Quantity:
- Payment:
- Shipping:
Inventory:2,077
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Product details
Overview
MAX6421US26 from Maxim Integrated is a low-power, active-low push-pull microprocessor reset supervisor IC designed for precise VCC monitoring and capacitor-adjustable reset timeout in space-constrained systems. It features a factory-trimmed 2.625V reset threshold (±2.5% over temperature), 1.6µA typical quiescent current, and guaranteed reset validity down to VCC = 1V. It is used in battery-powered controllers and portable equipment requiring reliable power-on reset with configurable delay.
For engineers reviewing the MAX6421US26 datasheet, MAX6421US26 pinout, MAX6421US26 application, or MAX6421US26 equivalent, key selection factors include its SOT143-4 package, push-pull active-low RESET output, capacitor-programmable timeout (275µs minimum), ±2.5% reset threshold accuracy over -40°C to +125°C, and immunity to sub-50µs VCC transients at 100mV overdrive.
Technical Context
The MAX6421US26 implements a precision voltage comparator with laser-trimmed internal resistors to monitor VCC against a 2.625V threshold, asserting RESET when VCC falls below that level. Its reset timeout is generated by a 240nA internal ramp current charging an external capacitor (CSRT) to a 0.65V internal reference.
Upon VCC recovery above threshold, the device holds RESET low for a programmable period defined as tRP = 2.73 × 10⁶ × CSRT + 275µs. The push-pull output drives low with VOL ≤ 0.4V at 3.2mA sink and high with VOH ≥ 0.8×VCC at 800µA source, ensuring robust logic-level compatibility across 1.6V–5.5V supply ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V ±2.5% over -40°C to +125°C - ensures accurate brownout detection across automotive/industrial temperature range |
| Quiescent Current | 1.6µA typical at +25°C - enables multi-year operation in coin-cell–powered devices |
| Reset Timeout Min | 275µs with CSRT = 0 - provides minimum guaranteed hold time for short-reset µP initialization |
| VCC Range | 1.0V to 5.5V - supports operation during deep brownout and compatibility with 1.8V/3.3V/5V systems |
| RESET Output Type | Active-low push-pull - eliminates need for external pullup and guarantees defined logic states at all valid VCC |
| VCC to RESET Delay | 80µs max at 1mV/µs VCC fall rate - ensures fast response to supply collapse without false triggering |
| Hysteresis | 4 × VTH = 10.5mV - prevents oscillation near threshold during slow VCC transitions |
Pinout & Package
MAX6421US26 is housed in a 4-pin SOT143-4 package (outline 21-0052), measuring 2.9mm × 1.6mm × 1.1mm, with gull-wing leads and RoHS-compliant finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Ground reference for internal comparator, ramp circuit, and output stage; must be low-impedance connection |
| 2 | RESET | Active-low push-pull output; sinks up to 3.2mA or sources up to 800µA; asserts low on VCC fault |
| 3 | SRT | Set Reset Timeout input; connects to external timing capacitor (CSRT); 240nA ramp current charges CSRT to 0.65V |
| 4 | VCC | Supply voltage and monitored rail; powers internal circuitry and sets reset threshold via internal resistor divider |
Key Features
| Feature | Design Value |
|---|---|
| Capacitor-adjustable reset timeout | Programmable from 275µs to >100ms using single external capacitor (CSRT), enabling µP-specific reset hold times |
| Guaranteed reset validity to VCC = 1V | RESET remains functional and electrically specified down to 1V supply, supporting ultra-low-voltage brownout detection |
| Immunity to short VCC transients | Rejects negative-going glitches ≤50µs duration when overdrive is ≤100mV below VTH - reduces false resets in noisy environments |
| Low-leakage SRT pin interface | 240nA precision ramp current source minimizes sensitivity to PCB leakage and stray capacitance; requires clean layout |
| Factory-trimmed reset threshold | 2.625V nominal with ±2.5% tolerance over full temperature range - eliminates external resistor calibration |
Applications
| Battery-Powered Controllers | Portable Medical Devices |
|---|---|
Use Scenario: A handheld glucose meter powered by a single CR2032 coin cell experiences gradual voltage decay during use and cold-temperature storage. IC Role / Device Role / Timing Role: MAX6421US26 monitors VCC and asserts RESET before the microcontroller enters undefined state, holding it in reset until stable 2.625V+ supply is restored. Use Value: Prevents corrupted EEPROM writes and erratic behavior during battery depletion, extending field reliability without firmware intervention. |
Use Scenario: An ambulatory ECG patch operates continuously for 72 hours on a rechargeable Li-ion cell, requiring fail-safe restart after deep discharge cycles. IC Role / Device Role / Timing Role: MAX6421US26 provides deterministic power-on reset with 10ms timeout (via 3.3nF CSRT), ensuring full µP initialization before sensor sampling begins. Use Value: Eliminates boot failures due to marginal VCC rise time, meeting IEC 60601-1 safety-critical startup requirements. |
| Automotive Body Control Modules | Industrial Sensor Nodes |
Use Scenario: A LIN bus node in a door module endures load-dump and cold-crank conditions where VCC dips below 3V for <100ms. IC Role / Device Role / Timing Role: MAX6421US26 detects VCC drop below 2.625V and holds µP in reset for 50ms (CSRT = 18nF), preventing partial execution during transient recovery. Use Value: Meets AEC-Q100 Grade 2 temperature requirements (-40°C to +105°C ambient) and avoids CAN/LIN communication faults caused by incomplete boot. |
Use Scenario: A wireless vibration sensor node deployed in oil-field equipment must survive wide-temperature swings and intermittent solar charging. IC Role / Device Role / Timing Role: MAX6421US26 supervises the 3.3V LDO output, asserting RESET during brownout and releasing only after stable VCC and 100ms timeout. Use Value: Ensures consistent wake-up sequence and flash memory integrity across -40°C to +85°C operating range with no software reset dependency. |
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 × 1.25mm) - 30% smaller footprint than SOT143 | Preferred for ultra-dense PCB layouts where board area is constrained more than height or thermal mass | Select MAX6421XS26-T when minimizing footprint is critical; verify reflow profile compatibility with SC70's smaller pad geometry |
| TLV803SDBZR | Fixed 2.63V threshold (±1.5%), 0.5µA IQ, 200ms fixed timeout, SOT23-3 - no capacitor adjustment, lower current, fewer pins | Suitable for cost-sensitive, non-configurable reset needs where timeout flexibility is unnecessary | Choose TLV803SDBZR only if fixed timeout suffices and 1.6µA vs. 0.5µA quiescent current is not decisive; lacks SRT programmability |
Compared with MAX6421US26, MAX6421XS26-T offers identical functionality in a smaller package but requires tighter assembly control, while TLV803SDBZR trades timeout adjustability and higher accuracy tolerance for lower cost and ultra-low IQ - neither is pin-compatible, and both require PCB redesign.
Availability
MAX6421US26 is available at Aetrix Electronics and suitable for battery-powered controllers, portable medical devices, and automotive body electronics requiring stable component supply, long-lifecycle support, and guaranteed -40°C to +125°C operation.
Supply support for MAX6421US26 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 precision voltage supervisor product line, engineered for ultra-low-power, capacitor-programmable reset timing in resource-constrained embedded systems where reliability under voltage stress is critical.
FAQ
What is the exact reset threshold voltage of MAX6421US26 and how tightly is it specified?
The MAX6421US26 has a factory-trimmed nominal reset threshold of 2.625V, with guaranteed accuracy of ±2.5% over the full operating temperature range of -40°C to +125°C. This specification is confirmed in the Electrical Characteristics table and applies to all units shipped under this part number - no binning or post-manufacture calibration is required.
Can MAX6421US26 operate reliably when VCC drops below 1.6V?
Yes, MAX6421US26 is fully specified down to VCC = 1.0V. Its reset function remains valid, and the push-pull RESET output maintains guaranteed VOL ≤ 0.4V (at 3.2mA) and VOH ≥ 0.8×VCC even at 1.0V supply. However, below 1.0V, output drive capability degrades, so system design should ensure µP reset assertion completes before VCC falls below 1.0V.
How do I calculate the external capacitor value for a 50ms reset timeout with MAX6421US26?
Use the formula CSRT = (tRP − 275µs) / 2.73×10⁶, where tRP is in seconds. For 50ms: CSRT = (0.05 − 0.000275) / 2.73×10⁶ ≈ 18.2nF. A standard 18nF ceramic capacitor (X7R, low-leakage) meets the requirement and yields ~49.8ms timeout per the Typical Operating Characteristics curve.
Is MAX6421US26 pin-compatible with any other Maxim reset supervisors?
No - MAX6421US26 uses a 4-pin SOT143 package with pinout GND/RESET/SRT/VCC. It is not pin-compatible with 5-pin SOT23 variants (e.g., MAX6424UK26-T) or open-drain versions (e.g., MAX6423US26-T), which have different pin counts and assignments. Direct replacement requires PCB layout change.
Does MAX6421US26 require any external components besides the SRT capacitor?
Only the SRT timing capacitor is required for basic operation. No external resistors, pullups, or bypass capacitors are mandatory. A 100nF VCC bypass capacitor is recommended for noise immunity but not specified as essential in the datasheet. The push-pull output eliminates need for external pullup resistors.
MAX6421US26 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 FAQ
1.How can I place an order for MAX6421US26 through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6421US26 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 reliable?
The price and inventory of MAX6421US26 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6421US26 is usually 5 days.
3.What payment methods are accepted for MAX6421US26?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6421US26 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6421US26?
MAX6421US26 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6421US26 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?
For technical support, including MAX6421US26 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6421US26 requirements.
6.How does Aetrix verify that MAX6421US26 is sourced from the original manufacturer or authorized distributors?
All MAX6421US26 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 meets industry standards.
7.What is the process for return or replacement of MAX6421US26?
All MAX6421US26 units undergo pre-shipment inspection (PSI). If there is an issue with MAX6421US26, 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 part is unused and in its original packaging.
Return procedure for MAX6421US26:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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