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Analog Devices Inc./Maxim Integrated MAX6821RUK+T
- Part No.:
- MAX6821RUK+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SC-74A, SOT-753
- Datasheet:
-
MAX6821RUK+T.pdf
- Description:
- IC MPU SUPERVISOR SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,514
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Product details
Overview
MAX6821RUK+T from Maxim Integrated is a low-voltage microprocessor supervisory IC in 5-pin SOT23 package, providing voltage monitoring (reset threshold = 2.63V), 140ms minimum reset timeout, and 1.6s watchdog timer with manual reset input. It asserts push-pull RESET and RESET outputs during VCC brownout, power-up, or software fault - used in embedded controllers and portable equipment requiring reliable µP initialization.
For engineers reviewing the MAX6821RUK+T datasheet, MAX6821RUK+T pinout, MAX6821RUK+T application, or MAX6821RUK+T equivalent, this page delivers verified circuit role, exact reset threshold, watchdog timing, supply current at temperature, and validated alternative parts for critical µP monitoring designs.
Technical Context
The MAX6821RUK+T integrates three core functions: precision voltage monitoring with ±0.03V threshold accuracy over -40°C to +125°C, a 1.6s watchdog timer cleared by WDI edge transitions, and debounced manual reset with internal 50kΩ pullup. Its dual-reset outputs (active-low push-pull RESET and active-high push-pull RESET) enable direct interface to bidirectional or level-sensitive µP reset pins without external logic.
Reset assertion is guaranteed valid down to VCC = +1.0V, and the device remains immune to negative VCC transients ≤20µs when overdrive is ≤100mV. All functions operate with zero external components and draw only 7–30µA supply current depending on VCC and temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.63V ±0.03V (R-suffix); precise brownout detection for 2.7V–3.6V systems |
| Reset Timeout Period | 140ms min (tRP); ensures µP completes power stabilization before release |
| Watchdog Timeout | 1.6s nominal (tWD); detects firmware hangs in real-time embedded loops |
| Supply Current | 7µA typ @ +3.6V, -40°C to +85°C; enables multi-year battery life in portable gear |
| Operating Voltage Range | +1.2V to +5.5V (TA = -40°C to +125°C); supports wide-input industrial rails |
| Reset Output Type | Push-pull RESET (active-low) and push-pull RESET (active-high); eliminates need for external pullups/pulldowns |
| Manual Reset Input | MR with 50kΩ internal pullup; accepts CMOS logic or momentary switch to GND - no debounce circuit required |
Pinout & Package
Package: 5-pin SOT23-5 (U5-1 outline, 21-0057 land pattern), RoHS-compliant, -40°C to +125°C operating range.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RESET (active-low) | Push-pull output asserted low during VCC drop, MR low, or watchdog timeout; drives µP reset pin directly |
| 2 | GND | Ground reference for all internal comparators, timers, and I/O; must be low-impedance connection |
| 3 | MR (manual reset) | Active-low input with internal 50kΩ pullup to VCC; initiates reset when pulled to GND for ≥1µs |
| 4 | WDI (watchdog input) | Edge-sensitive input; toggling within 1.6s prevents reset; left unconnected disables watchdog |
| 5 | VCC | Supply and monitored voltage rail; reset triggers when VCC falls below 2.63V; valid operation down to 1.0V |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent reset outputs | Simultaneous active-low RESET and active-high RESET eliminate level-shifting or inverters in mixed-logic systems |
| Guaranteed reset validity to VCC = +1.0V | Ensures deterministic reset behavior during deep brownout or battery sag - no undefined state risk |
| No external components required | Reduces BOM count, PCB area, and qualification effort; qualifies as single-chip supervisory solution |
| Immunity to short negative VCC transients | Withstands ≤20µs glitches down to VTH −100mV without spurious reset - avoids false triggers in noisy environments |
| Debounced manual reset with internal pullup | Enables direct switch-to-GND connection; eliminates RC network, saves layout space and debug time |
Applications
| Set-Top Boxes | Embedded Controllers |
|---|---|
|
Use Scenario: Power sequencing and firmware crash recovery in cable/satellite STBs with ARM-based SoCs. IC Role / Device Role / Timing Role: Supervisory IC asserting RESET during 3.3V rail brownout and generating watchdog-triggered reset if UI thread locks. Use Value: Prevents frozen UI and channel tuning failure by enforcing hard reset within 140ms of fault detection. |
Use Scenario: Industrial PLC modules requiring fail-safe startup and runtime integrity checks. IC Role / Device Role / Timing Role: Monitors 2.7V auxiliary supply and feeds WDI from FPGA heartbeat signal; MR tied to front-panel reset button. Use Value: Guarantees deterministic boot state after power interruption and enables field technician-initiated recovery without power cycle. |
| Portable/Battery-Powered Equipment | Critical µP Monitoring |
|
Use Scenario: Handheld test instruments powered by Li-ion batteries with dynamic voltage sag under load. IC Role / Device Role / Timing Role: Tracks battery voltage decay; asserts RESET when cell drops below 2.63V and holds it for 140ms to prevent partial boot. Use Value: Eliminates corrupted memory writes and flash corruption during low-battery shutdown sequences. |
Use Scenario: Medical infusion pump controller where µP lockup could compromise dose accuracy. IC Role / Device Role / Timing Role: Dual-reset outputs drive both main µP and safety monitor MCU; watchdog fed by critical task scheduler. Use Value: Provides redundant reset signaling and hardware-enforced watchdog timeout - meets IEC 62304 Class C requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6822RUK+T | Open-drain RESET instead of push-pull RESET; identical threshold (2.63V), timeout, and watchdog | Required when interfacing to µPs with bidirectional reset pins (e.g., Motorola 68HC11) needing external pullup | Select MAX6822RUK+T only if open-drain output compatibility is mandatory; otherwise MAX6821RUK+T offers simpler drive capability. |
| TPS3808G33DBVR | Single active-low reset output; 3.3V fixed threshold; 200ms timeout; no manual reset input; 1.6s watchdog | Suitable for 3.3V-only systems without manual reset requirement; lacks dual-reset flexibility and MR function | Choose TPS3808G33DBVR for cost-sensitive 3.3V applications without MR need; MAX6821RUK+T retains full feature set including MR and dual outputs. |
Compared with MAX6822RUK+T, MAX6821RUK+T provides direct-drive push-pull RESET eliminating external pullup resistors; versus TPS3808G33DBVR, it adds manual reset, dual-output capability, and wider voltage range - critical for multi-rail or field-serviceable designs.
Availability
MAX6821RUK+T is available at Aetrix Electronics and suitable for embedded controllers, portable/battery-powered equipment, and critical µP monitoring applications requiring stable component supply, long-term lifecycle support, and automotive-grade temperature range (-40°C to +125°C).
Supply support for MAX6821RUK+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) designs precision analog and mixed-signal ICs for industrial, computing, and communications markets, with emphasis on reliability-critical functions.
The MAX6821RUK+T belongs to the MAX6821–MAX6825 family of low-voltage µP supervisors engineered for robust power-on reset, brownout protection, and software fault recovery in space-constrained embedded systems.
FAQ
What is the exact reset threshold voltage for MAX6821RUK+T?
The MAX6821RUK+T has a factory-trimmed reset threshold of 2.63V (R-suffix), specified with ±0.03V tolerance over -40°C to +125°C. This value is guaranteed per the Threshold Suffix Guide and Electrical Characteristics table, enabling precise brownout detection for 2.7V–3.6V supply rails without external calibration.
Does MAX6821RUK+T support manual reset functionality?
Yes, MAX6821RUK+T includes a dedicated MR (manual reset) input on Pin 3 with an internal 50kΩ pullup resistor. Pulling MR low for ≥1µs asserts both RESET and RESET outputs for the full 140ms timeout period. The input accepts CMOS logic levels and can be driven directly by a momentary switch to GND - no external debounce components needed.
How does the watchdog timer in MAX6821RUK+T operate?
The MAX6821RUK+T watchdog timer has a nominal 1.6s timeout period (tWD). It is cleared by any rising or falling edge on the WDI pin (Pin 4). If no edge occurs within 1.6s, the device asserts RESET and RESET for 140ms. Leaving WDI unconnected disables the watchdog, as the internal driver resets the timer every ~1.4s.
What are the absolute maximum ratings for MAX6821RUK+T?
Per the datasheet, MAX6821RUK+T has VCC to GND rating of -0.3V to +6.0V, push-pull output voltage range of -0.3V to (VCC + 0.3V), and continuous power dissipation of 571mW at +70°C (derated 7.1mW/°C above). Junction temperature must not exceed +150°C, and storage temperature range is -65°C to +150°C.
Can MAX6821RUK+T operate reliably at low supply voltages?
Yes, MAX6821RUK+T guarantees correct reset output states down to VCC = +1.0V, and operates across 1.2V to 5.5V. Its supply current is as low as 7µA at +3.6V and room temperature, making it suitable for ultra-low-power applications such as coin-cell–powered instrumentation where extended battery life is essential.
MAX6821RUK+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.63V
- 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
MAX6821RUK+T FAQ
1.How can I place an order for MAX6821RUK+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6821RUK+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 MAX6821RUK+T reliable?
The price and inventory of MAX6821RUK+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6821RUK+T is usually 5 days.
3.What payment methods are accepted for MAX6821RUK+T?
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Note: Certain payment methods may incur a processing fee.
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MAX6821RUK+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6821RUK+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 MAX6821RUK+T?
For technical support, including MAX6821RUK+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6821RUK+T requirements.
6.How does Aetrix verify that MAX6821RUK+T is sourced from the original manufacturer or authorized distributors?
All MAX6821RUK+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 MAX6821RUK+T meets industry standards.
7.What is the process for return or replacement of MAX6821RUK+T?
All MAX6821RUK+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6821RUK+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 MAX6821RUK+T part is unused and in its original packaging.
Return procedure for MAX6821RUK+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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