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Analog Devices Inc./Maxim Integrated MAX6821WUK+
- Part No.:
- MAX6821WUK+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SC-74A, SOT-753
- Datasheet:
-
MAX6821WUK+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:917
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Product details
Overview
MAX6821WUK+ from Maxim Integrated is a low-voltage microprocessor supervisory IC in 5-pin SOT23 package, combining voltage monitoring (1.67V threshold), 140ms minimum reset timeout, 1.6s watchdog timer, manual reset input, and push-pull active-low RESET output. It ensures reliable µP startup and brownout recovery in portable/battery-powered equipment and embedded controllers.
For engineers reviewing the MAX6821WUK+ datasheet, MAX6821WUK+ pinout, MAX6821WUK+ application, or MAX6821WUK+ equivalent, this page delivers verified functional identity, exact pin roles, confirmed operating parameters across -40°C to +125°C, and real-world selection guidance for critical µP monitoring designs.
Technical Context
The MAX6821WUK+ implements a precision bandgap-based voltage monitor with ±1.5% threshold accuracy at 1.67V over temperature, a monostable reset generator with guaranteed 140ms–320ms timeout, and a watchdog timer cleared by WDI edge transitions. Its internal 50kΩ MR pullup enables direct switch interfacing without external components.
RESET assertion occurs on VCC drop below 1.67V, MR low, or WDI timeout; reset remains asserted for full timeout after recovery. The push-pull RESET output drives low to ≤0.3V at 500µA sink and high to ≥0.8×VCC at 200µA source, with valid operation down to VCC = +1.0V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 1.67V ±1.5% (guaranteed over -40°C to +125°C; enables reliable monitoring of 1.8V supply rails) |
| Reset Timeout Period | 140ms min (ensures µP remains held in reset long enough for stable power rail settling) |
| Watchdog Timeout | 1.6s nominal (detects firmware hangs in deeply embedded systems without requiring software polling) |
| VCC Operating Range | +1.2V to +5.5V (supports wide supply range including 1.8V, 2.5V, 3.3V, and 5V systems) |
| RESET Output Type | Push-pull active-low (drives directly into µP reset pin without external pull-up; eliminates open-drain ambiguity) |
| MR Input Logic | Active-low with 50kΩ internal pullup (allows momentary switch-to-GND interface; no external resistor needed) |
| Supply Current | 25µA max at +125°C (enables ultra-low-power operation in battery-backed applications) |
Pinout & Package
Package: 5-pin SOT23-5 (U5-1 outline, 21-0057 land pattern), RoHS-compliant, rated for -40°C to +125°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RESET (active-low) | Push-pull output asserted low during VCC undervoltage, MR activation, or watchdog timeout; drives µP reset pin directly |
| 2 | GND | Ground reference for all internal circuitry and reset timing; must be low-impedance connection |
| 3 | MR (manual reset) | Active-low input with internal 50kΩ pullup to VCC; asserts reset when pulled ≤0.3×VCC; debounced internally |
| 4 | WDI (watchdog input) | Edge-sensitive input; toggling within 1.6s prevents reset; left unconnected disables watchdog function |
| 5 | VCC | Power supply and monitored voltage input; reset triggers when VCC falls below 1.67V; valid down to +1.0V |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset validity to VCC = +1.0V | Ensures deterministic reset behavior during deep brownout conditions where other supervisors may release prematurely |
| No external components required | Integrates voltage reference, timer, pullup resistor, and logic-reduces BOM count and PCB footprint vs. discrete solutions |
| Immunity to short negative VCC transients | Withstands ≤20µs transients down to 100mV below threshold without spurious reset-improves system robustness in noisy environments |
| 1.6s watchdog timeout with edge-triggered clear | Eliminates need for precise software pulse timing; any WDI transition resets timer, simplifying firmware integration |
| Five-pin SOT23 package | Enables space-constrained designs in portable equipment while maintaining thermal performance up to +125°C |
Applications
| Portable/Battery-Powered Equipment | Critical µP Monitoring |
|---|---|
|
Use Scenario: Power management in handheld medical devices with Li-ion battery supply that drops from 4.2V to 2.8V during discharge. IC Role / Device Role / Timing Role: Voltage supervisor asserting reset when battery falls below 1.67V, preventing corrupted memory writes during brownout. Use Value: Prevents data corruption and unsafe operation by holding µP in reset until battery recovers or shuts down cleanly. |
Use Scenario: Industrial PLC controller requiring fail-safe restart after unexpected power interruption. IC Role / Device Role / Timing Role: Dual-fault detector monitoring both supply voltage and software execution via watchdog timer. Use Value: Guarantees system recovery from both hardware (undervoltage) and software (hang) faults without operator intervention. |
| Embedded Controllers | Intelligent Instruments |
|
Use Scenario: Remote sensor node powered by energy harvesting, with intermittent 1.8V rail availability. IC Role / Device Role / Timing Role: Supervisor ensuring µP only executes firmware when VCC ≥1.67V and watchdog is serviced. Use Value: Eliminates boot failures and erratic behavior caused by marginal supply conditions during cold-start. |
Use Scenario: Portable multimeter with µP-based measurement engine and LCD display. IC Role / Device Role / Timing Role: Reset coordinator managing clean power-up sequence and manual recalibration trigger via MR input. Use Value: Enables field recalibration using simple button press without firmware modification or debug interface. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6326UT29D3+ | Fixed 2.93V threshold, 1.6s watchdog, open-drain RESET, same SOT23-5 package | Lacks manual reset input; requires external pull-up for RESET; suited for systems with bidirectional µP reset pins | Select when 2.93V threshold matches system supply and open-drain interface is preferred |
| TPS3808G16DBVR | 1.6V threshold (±0.5%), 200ms reset timeout, no watchdog, push-pull RESET, same SOT23-5 | Missing watchdog and manual reset; lower threshold tolerance but tighter accuracy; higher ICC (12µA typ) | Select when watchdog and MR are unnecessary and highest threshold accuracy is prioritized over fault coverage |
Compared with MAX6821WUK+, MAX6326UT29D3+ offers identical watchdog and package but omits MR and uses open-drain RESET-requiring layout changes for pull-up and limiting reset control flexibility. TPS3808G16DBVR provides superior threshold accuracy but sacrifices two critical reliability features (watchdog and MR), narrowing its suitability to simpler power-monitoring-only use cases.
Availability
MAX6821WUK+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, critical µP monitoring, and embedded controllers requiring stable component supply with extended temperature support (-40°C to +125°C).
Supply support for MAX6821WUK+ 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) designs precision analog and mixed-signal ICs for power, sensing, and interface applications, with focus on high-reliability industrial and automotive markets.
The MAX6821WUK+ belongs to the MAX682x family of low-voltage µP supervisors engineered specifically for robust, single-chip power monitoring and fault recovery in space-constrained embedded systems.
FAQ
What is the exact reset threshold voltage of the MAX6821WUK+?
The MAX6821WUK+ has a factory-trimmed reset threshold of 1.67V, specified with ±1.5% tolerance over the full operating temperature range (-40°C to +125°C). This value is confirmed in the Threshold Suffix Guide where "W" denotes 1.67V, and electrical characteristics tables list min/typ/max values of 1.61V/1.67V/1.72V at -40°C to +125°C. The MAX6821WUK+ uses this threshold to monitor 1.8V supply rails with sufficient margin.
Does the MAX6821WUK+ include a watchdog timer and manual reset input?
Yes, the MAX6821WUK+ integrates both a 1.6s watchdog timer and an active-low manual reset (MR) input with internal 50kΩ pullup resistor. These functions are explicitly confirmed in the General Description, Selector Guide, and Pin Description sections of the datasheet. The MR input allows external switch or logic control, while the watchdog monitors WDI edge transitions to detect firmware hangs-both features are present in the MAX6821 variant per the ordering table and functional diagrams.
What type of RESET output does the MAX6821WUK+ provide?
The MAX6821WUK+ provides a push-pull active-low RESET output, as confirmed in the Selector Guide (MAX6821 row shows "✔" under "ACTIVE-LOW RESET") and Pin Description (Pin 1 labeled "RESET (active-low)" with push-pull drive capability). This output drives low to ≤0.3V at 500µA sink and high to ≥0.8×VCC at 200µA source, eliminating the need for an external pull-up resistor unlike open-drain alternatives.
What is the minimum VCC voltage at which the MAX6821WUK+ guarantees correct RESET state?
The MAX6821WUK+ guarantees correct RESET output state down to VCC = +1.0V, as stated in the General Description ("outputs are guaranteed to be in the correct state for VCC down to +1.0V") and confirmed in Absolute Maximum Ratings and Electrical Characteristics. This ensures deterministic reset behavior during severe brownout conditions where VCC collapses below normal operating range, a key reliability feature distinguishing it from many competing supervisors.
Is the MAX6821WUK+ compatible with 1.8V supply systems?
Yes, the MAX6821WUK+ is fully compatible with 1.8V supply systems. Its 1.67V reset threshold provides appropriate margin above typical 1.8V rail dropout, and its VCC operating range extends from +1.2V to +5.5V. Electrical characteristics confirm operation at VCC = +1.8V (e.g., RESET output HIGH specified at VCC ≥ 1.8V, ISOURCE = 200µA), and typical operating curves include data for +1.8V VCC. The device is explicitly listed for "+1.8V…Supplies" in the Features section.
MAX6821WUK+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 1.67V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
MAX6821WUK+ FAQ
1.How can I place an order for MAX6821WUK+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6821WUK+ 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 MAX6821WUK+ reliable?
The price and inventory of MAX6821WUK+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6821WUK+ is usually 5 days.
3.What payment methods are accepted for MAX6821WUK+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6821WUK+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6821WUK+?
MAX6821WUK+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6821WUK+ 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 MAX6821WUK+?
For technical support, including MAX6821WUK+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6821WUK+ requirements.
6.How does Aetrix verify that MAX6821WUK+ is sourced from the original manufacturer or authorized distributors?
All MAX6821WUK+ 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 MAX6821WUK+ meets industry standards.
7.What is the process for return or replacement of MAX6821WUK+?
All MAX6821WUK+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6821WUK+, 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 MAX6821WUK+ part is unused and in its original packaging.
Return procedure for MAX6821WUK+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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