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Analog Devices Inc./Maxim Integrated MAX6821WUK-T
- Part No.:
- MAX6821WUK-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SC-74A, SOT-753
- Datasheet:
-
MAX6821WUK-T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:7,500
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Product details
Overview
MAX6821WUK-T from Maxim Integrated is a low-voltage microprocessor supervisory circuit in 5-pin SOT23 package, featuring push-pull active-low RESET output, 1.67V reset threshold, 140ms minimum reset timeout, 1.6s watchdog timeout, and debounced manual reset input. It monitors VCC supply integrity for critical µP systems in portable/battery-powered equipment and embedded controllers.
For engineers reviewing the MAX6821WUK-T datasheet, MAX6821WUK-T pinout, MAX6821WUK-T application, or MAX6821WUK-T equivalent, this device supports precise brownout detection down to VCC = +1.0V, immune short negative VCC transients, and requires no external components for full supervision functionality.
Technical Context
The MAX6821WUK-T integrates voltage monitoring, watchdog timer, and manual reset in a single BiCMOS IC. Its reset generator asserts active-low RESET when VCC falls below 1.67V (±3% over -40°C to +125°C), holding it for ≥140ms after VCC recovers above threshold.
The watchdog circuit triggers reset if WDI remains static >1.6s (min 1.12s, max 2.4s over temperature); MR input features internal 50kΩ pullup and 200ns MR-to-reset delay. All logic thresholds scale with VCC (VIH = 0.7×VCC, VIL = 0.3×VCC).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 1.67V ±3% - sets brownout detection point for +1.53V to +2.0V VCC range systems |
| Reset Timeout Period | 140ms min - ensures µP remains held in reset long enough for stable power-up sequencing |
| Watchdog Timeout | 1.6s nominal - provides robust software execution monitoring without excessive false triggers |
| VCC Operating Range | +1.2V to +5.5V - supports operation down to 1.2V while guaranteeing reset validity to 1.0V |
| Supply Current | 25µA max at -40°C to +125°C - enables ultra-low-power supervision in battery-critical designs |
| RESET Output Type | Push-pull active-low - drives directly into µP reset pin without external pullup resistor |
| MR Input | Debounced, internal 50kΩ pullup - eliminates need for external RC network or switch debounce circuitry |
Pinout & Package
MAX6821WUK-T uses a 5-pin SOT23-5 package (U5-1 outline, land pattern 21-0057), optimized for space-constrained PCB layouts in portable and embedded applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RESET | Active-low push-pull reset output - asserts low during VCC brownout, MR activation, or watchdog timeout |
| 2 | GND | Ground reference - common return path for all internal circuits and reset assertion |
| 3 | MR | Active-low manual reset input - internally pulled up to VCC; logic low forces reset for ≥140ms |
| 4 | WDI | Watchdog input - toggling within 1.6s prevents reset; static high/low longer than timeout triggers reset |
| 5 | VCC | Supply voltage and monitored rail - powers device and serves as input to reset threshold comparator |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset validity to VCC = +1.0V | Ensures reliable reset assertion even during deep brownout conditions where VCC drops below normal operating minimum |
| No external components required | Reduces BOM count and board area - all supervision functions implemented monolithically in SOT23-5 |
| Immunity to short negative VCC transients | Prevents spurious resets from noise or switching glitches on power rail (e.g., ≤20µs at 100mV overdrive) |
| 1.6s watchdog with 50ns pulse detection | Enables tight software monitoring without missing brief WDI transitions in high-speed firmware loops |
| MR input with 200ns propagation delay | Supports fast manual reset initiation for test/debug scenarios without timing uncertainty |
Applications
| Set-Top Boxes | Portable/Battery-Powered Equipment |
|---|---|
Use Scenario: Power management during channel switching and firmware updates in consumer STBs. IC Role / Device Role / Timing Role: Supervises main SoC VCC rail and asserts reset if supply dips during dynamic load changes. Use Value: Prevents corrupted firmware writes and system lockups by enforcing clean reset before reinitialization. | Use Scenario: Long-term operation on coin-cell or Li-ion batteries in handheld instruments. IC Role / Device Role / Timing Role: Monitors battery voltage decay and initiates controlled shutdown or reset before undervoltage lockout. Use Value: Extends usable battery life by enabling operation down to 1.2V while maintaining guaranteed reset behavior to 1.0V. |
| Embedded Controllers | Critical µP Monitoring |
Use Scenario: Industrial PLC modules requiring deterministic boot and fault recovery. IC Role / Device Role / Timing Role: Provides independent reset generation synchronized to VCC, MR, and watchdog events. Use Value: Eliminates reliance on µP's internal reset circuitry, improving system-level reliability under EMI or thermal stress. | Use Scenario: Medical diagnostic devices where uncontrolled µP operation could compromise safety. IC Role / Device Role / Timing Role: Acts as hardware-enforced fail-safe, asserting reset on any code hang, power anomaly, or operator-initiated emergency stop. Use Value: Meets IEC 62304 Class C requirements by providing externally verified reset assurance beyond software-only checks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6822WUK-T | Open-drain RESET output instead of push-pull; identical threshold, timeout, and watchdog specs | Required when interfacing with µPs having bidirectional reset pins (e.g., Motorola 68HC11) needing external pullup | Select MAX6822WUK-T only if system design mandates open-drain drive capability or shared reset bus topology |
| TPS3808G16DBVR | 1.6V threshold (vs. 1.67V), 200ms reset timeout (vs. 140ms), no manual reset input, same 1.6s watchdog | Lacks MR pin - unsuitable for applications requiring operator-initiated reset or test-mode entry | Choose TPS3808G16DBVR only for cost-sensitive, MR-free designs where tighter threshold tolerance and longer timeout are acceptable |
Compared with MAX6822WUK-T, MAX6821WUK-T offers direct-drive reset capability eliminating external pullup; versus TPS3808G16DBVR, it adds manual reset and shorter timeout for faster recovery - both tradeoffs impact PCB layout, firmware initialization flow, and field serviceability.
Availability
MAX6821WUK-T is available at Aetrix Electronics and suitable for set-top boxes, portable/battery-powered equipment, and embedded controllers requiring stable component supply across industrial temperature ranges (-40°C to +125°C).
Supply support for MAX6821WUK-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 is a semiconductor company specializing in analog and mixed-signal ICs for power, sensing, and interface applications.
The MAX6821–MAX6825 family was designed specifically for low-voltage microprocessor supervision in space- and power-constrained systems, integrating voltage monitoring, watchdog, and manual reset in minimal 5-pin SOT23 packaging.
FAQ
What is the exact reset threshold voltage for MAX6821WUK-T and how tightly is it specified?
The MAX6821WUK-T has a factory-trimmed reset threshold of 1.67V, with guaranteed tolerance of ±3% over the full operating temperature range (-40°C to +125°C). This value is confirmed in the Electrical Characteristics table under "MAX682_W" suffix, where VTH min = 1.61V and max = 1.72V at -40°C to +125°C. The MAX6821WUK-T is therefore optimized for systems powered by +1.53V to +2.0V supplies.
Does MAX6821WUK-T support operation at VCC below its nominal 1.67V threshold?
Yes, MAX6821WUK-T guarantees correct reset output state down to VCC = +1.0V - meaning the RESET pin remains asserted (low) even as VCC collapses below 1.67V, ensuring µP stays held in reset through deep brownout. This is explicitly stated in the General Description and validated in the Absolute Maximum Ratings section.
How does the watchdog timer in MAX6821WUK-T interact with the manual reset input?
In MAX6821WUK-T, the watchdog timer and manual reset (MR) are independent but share the same reset assertion mechanism: either event forces RESET low for the full 140ms timeout period. Asserting MR clears the watchdog timer, and triggering the watchdog does not affect MR functionality. Both paths converge at the reset generator, ensuring deterministic behavior regardless of trigger source.
Can the MR input of MAX6821WUK-T be left unconnected without external pullup?
Yes, the MR input of MAX6821WUK-T includes an internal 50kΩ pullup resistor to VCC, so it may be left floating or tied to VCC if manual reset functionality is unused. This eliminates the need for external components and simplifies PCB layout - a key design advantage confirmed in the Pin Description and Applications Information sections.
What is the maximum allowable leakage current on the WDI pin of MAX6821WUK-T when unused?
When WDI is left unconnected or three-stated, MAX6821WUK-T specifies a maximum leakage current of 10µA and maximum load capacitance of 200pF to ensure reliable watchdog disablement. This is documented in the Applications Information section under "Disable the watchdog function", confirming safe operation without external termination.
MAX6821WUK-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Bulk
- Product Status:
- Active
- 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-T FAQ
1.How can I place an order for MAX6821WUK-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6821WUK-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 MAX6821WUK-T reliable?
The price and inventory of MAX6821WUK-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6821WUK-T is usually 5 days.
3.What payment methods are accepted for MAX6821WUK-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6821WUK-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6821WUK-T?
MAX6821WUK-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6821WUK-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 MAX6821WUK-T?
For technical support, including MAX6821WUK-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6821WUK-T requirements.
6.How does Aetrix verify that MAX6821WUK-T is sourced from the original manufacturer or authorized distributors?
All MAX6821WUK-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 MAX6821WUK-T meets industry standards.
7.What is the process for return or replacement of MAX6821WUK-T?
All MAX6821WUK-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6821WUK-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 MAX6821WUK-T part is unused and in its original packaging.
Return procedure for MAX6821WUK-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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