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Analog Devices Inc./Maxim Integrated MAX6721UTZWD3+
- Part No.:
- MAX6721UTZWD3+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX6721UTZWD3+.pdf
- Description:
- MAX6721UTZWD3+
- Quantity:
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Inventory:762
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Product details
Overview
MAX6721UTZWD3+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit in 6-pin SOT23 package, monitoring VCC1 (4.625V threshold) and VCC2 (3.075V threshold) with 210ms reset timeout, watchdog timer (35s startup / 1.12s normal), and open-drain active-low RST output. It ensures reliable system reset during power-up, brownout, or software fault in battery-powered telecom and industrial controllers.
For engineers reviewing the MAX6721UTZWD3+ datasheet, MAX6721UTZWD3+ pinout, MAX6721UTZWD3+ application, or MAX6721UTZWD3+ equivalent, key selection criteria include dual-supply monitoring range (1.8–5.0V / 0.9–3.3V), guaranteed reset validity down to VCC = 0.8V, low 14µA supply current, and integrated watchdog with long-startup/short-normal timing modes.
Technical Context
The MAX6721UTZWD3+ implements a dual-threshold comparator architecture with independent VCC1 and VCC2 sensing paths, each referenced to factory-trimmed precision voltage references (±1.5% over temperature). Its reset logic combines asynchronous detection with a digital timeout counter ensuring minimum assertion duration regardless of supply recovery speed.
It integrates a dual-mode watchdog timer: after any reset event, it enters a 35s minimum startup mode to accommodate boot sequences, then transitions to 1.12s minimum normal mode upon first WDI edge detection. The WDI input accepts CMOS/TTL levels and clears on rising or falling edges, preventing false timeouts during transient noise.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Reset Threshold | 4.625V (factory-trimmed, ±1.5% over -40°C to +85°C; sets primary supply fail point) |
| VCC2 Reset Threshold | 3.075V (factory-trimmed, ±1.5% over -40°C to +85°C; sets secondary supply fail point) |
| Reset Timeout Period | 210ms (minimum; ensures µP reset pulse meets minimum hold time requirements) |
| Watchdog Timeout | 35s min startup / 1.12s min normal (dual-mode timing prevents boot failure while enabling rapid fault detection) |
| Supply Current | 14µA typical at 3.6V (enables multi-year operation in coin-cell–powered systems) |
| Operating Temperature | -40°C to +85°C (supports industrial and extended-temperature embedded deployments) |
| Reset Output Type | Open-drain active-low RST (requires external pullup; compatible with bidirectional µP reset pins) |
Pinout & Package
MAX6721UTZWD3+ is housed in a 6-pin SOT23-6 package (1.6mm × 2.9mm × 1.1mm), optimized for space-constrained PCB layouts in portable and telecom equipment.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low open-drain reset output; asserts when VCC1/VCC2 drop below thresholds or WDI timeout occurs; requires external pullup |
| 2 | GND | Ground reference for all internal comparators, timers, and I/O; must be low-impedance connection |
| 3 | MR | Active-low manual reset input; internal 50kΩ pullup to VCC1; 1µs minimum pulse width required for reliable assertion |
| 4 | VCC2 | Secondary supply input (0.9–3.3V range); powers internal VCC2 comparator and sets RST2 reference if enabled |
| 5 | VCC1 | Primary supply input (1.8–5.0V range); powers device core, enables VCC1 comparator, and references RST output |
| 6 | WDI | Watchdog input; rising or falling edge resets 1.12s timer; held high/low >35s triggers initial reset after power-up |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent voltage monitors | VCC1 (4.625V) and VCC2 (3.075V) thresholds with ±1.5% accuracy ensure precise, decoupled supply supervision |
| Dual-mode watchdog timer | 35s startup window accommodates full system boot; 1.12s normal mode enables fast software hang detection |
| Guaranteed reset validity down to 0.8V | Ensures clean reset assertion even during deep brownout conditions before complete power collapse |
| Low 14µA supply current | Minimizes quiescent drain on backup batteries or energy-harvesting sources in always-on systems |
| Immunity to short VCC transients | Rejects <20µs glitches below threshold, preventing spurious resets in noisy power environments |
Applications
| Telecom Line Card Power Monitoring | Industrial PLC CPU Supervision |
|---|---|
Use Scenario: Monitors primary 3.3V logic rail and secondary 2.5V I/O rail on a carrier-grade line card with hot-swap capability. IC Role / Device Role / Timing Role: Dual-supply supervisor asserting RST during simultaneous or staggered rail failures; 210ms timeout aligns with FPGA configuration hold requirements. Use Value: Prevents partial configuration and metastability by guaranteeing µP reset until both rails stabilize above 4.625V and 3.075V respectively. |
Use Scenario: Embedded in programmable logic controller mainboard to supervise 5.0V CPU core and 3.3V communication interface supplies. IC Role / Device Role / Timing Role: Watchdog-enabled supervisor detecting firmware lockups via WDI polling; MR supports field-service reset via front-panel button. Use Value: Eliminates need for external RC reset circuits and discrete watchdog ICs-reducing BOM count by two components. |
| Battery-Powered IoT Gateway | Medical Diagnostic Handheld |
Use Scenario: Powers from single Li-ion cell (2.8–4.2V) with buck-boost generating 3.3V (VCC1) and 1.8V (VCC2) rails. IC Role / Device Role / Timing Role: Dual-threshold monitor ensuring reset during cell voltage sag below 3.0V (VCC1) or LDO dropout (VCC2); low 14µA ICC extends battery life. Use Value: Enables graceful shutdown and data preservation when battery reaches end-of-discharge without requiring µP intervention. |
Use Scenario: Used in FDA-cleared handheld ultrasound device where continuous operation and fault-free boot are critical. IC Role / Device Role / Timing Role: Supervises 3.3V analog front-end and 1.2V digital core; watchdog guards against real-time processing stalls during image acquisition. Use Value: Meets IEC 62304 Class C software safety requirements by providing hardware-enforced reset on processor hang. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6722UTZWD3+ | Push-pull RST output instead of open-drain; same thresholds, timeout, and watchdog specs | Requires no external pullup resistor; incompatible with bidirectional µP reset pins without series resistor | Select MAX6722UTZWD3+ when driving standard CMOS inputs directly and board layout prohibits external pullup placement. |
| TPS3808G33DBVR | Single-supply monitor (3.3V only); no watchdog; 200ms timeout; 2.5µA ICC; SOT23-6 | Lacks VCC2 monitoring and WDI functionality; suitable only for single-rail systems with ultra-low-power priority | Choose TPS3808G33DBVR only if dual-supply supervision and watchdog are unnecessary and sub-3µA quiescent current is mandatory. |
Compared with MAX6721UTZWD3+, MAX6722UTZWD3+ simplifies output interfacing but sacrifices bidirectional µP compatibility, while TPS3808G33DBVR reduces power consumption by 82% but eliminates critical dual-rail and watchdog capabilities required for robust embedded control.
Availability
MAX6721UTZWD3+ is available at Aetrix Electronics and suitable for telecom line cards, industrial PLCs, battery-powered IoT gateways, and medical handhelds requiring stable component supply across extended temperature and long product lifecycles.
Supply support for MAX6721UTZWD3+ 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 demanding industrial, automotive, and communications applications, emphasizing reliability, integration, and low-power operation.
The MAX6715–MAX6729 family delivers compact, ultra-low-power supervisory solutions for multivoltage embedded systems where guaranteed reset behavior, watchdog safety, and minimal footprint are essential design requirements.
FAQ
What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6721UTZWD3+?
The MAX6721UTZWD3+ has factory-trimmed reset thresholds of 4.625V for VCC1 and 3.075V for VCC2, specified with ±1.5% tolerance over the full -40°C to +85°C operating range. These values are encoded in the "ZW" suffix per Maxim's Reset Voltage Threshold Suffix Guide and are not user-adjustable. The MAX6721UTZWD3+ does not support external adjustment of these primary thresholds.
Does the MAX6721UTZWD3+ support monitoring a third voltage rail?
No, the MAX6721UTZWD3+ is a dual-voltage supervisor and does not include the RSTIN input required for auxiliary voltage monitoring. That feature is present only in MAX6719/MAX6720/MAX6723–MAX6727 variants. The MAX6721UTZWD3+ monitors only VCC1 and VCC2, with no provision for a third monitored supply.
What is the function of the WDI pin on the MAX6721UTZWD3+ and how should it be driven?
The WDI (watchdog input) pin on the MAX6721UTZWD3+ monitors µP activity: a rising or falling edge resets the 1.12s normal watchdog timer. After power-up or any reset, it first enters a 35s startup mode. WDI accepts standard CMOS/TTL logic levels (VIH = 0.7×VCC1, VIL = 0.3×VCC1) and draws less than ±1µA. It must be toggled regularly during firmware execution to prevent timeout-induced reset.
Is the MAX6721UTZWD3+ pin-compatible with other devices in the MAX6715–MAX6729 family?
The MAX6721UTZWD3+ uses a 6-pin SOT23-6 package and shares identical pinout with MAX6715/MAX6716/MAX6719/MAX6720/MAX6722/MAX6723/MAX6724. However, functional differences exist: MAX6721UTZWD3+ provides open-drain RST and WDI but no PFI/PFO or RST2. Pin compatibility does not imply functional interchangeability-always verify feature alignment per Selector Guide before substitution.
What is the minimum supply voltage at which the MAX6721UTZWD3+ guarantees correct reset output logic state?
The MAX6721UTZWD3+ guarantees valid reset output logic state as long as either VCC1 or VCC2 remains above 0.8V. Below this level, reset behavior is not specified. This 0.8V guarantee enables reliable operation during deep brownout conditions and supports graceful shutdown sequencing in systems with cascaded regulators or battery discharge profiles.
MAX6721UTZWD3+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX6721UTZWD3+ FAQ
1.How can I place an order for MAX6721UTZWD3+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6721UTZWD3+ 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 MAX6721UTZWD3+ reliable?
The price and inventory of MAX6721UTZWD3+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6721UTZWD3+ is usually 5 days.
3.What payment methods are accepted for MAX6721UTZWD3+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6721UTZWD3+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6721UTZWD3+?
MAX6721UTZWD3+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6721UTZWD3+ 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 MAX6721UTZWD3+?
For technical support, including MAX6721UTZWD3+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6721UTZWD3+ requirements.
6.How does Aetrix verify that MAX6721UTZWD3+ is sourced from the original manufacturer or authorized distributors?
All MAX6721UTZWD3+ 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 MAX6721UTZWD3+ meets industry standards.
7.What is the process for return or replacement of MAX6721UTZWD3+?
All MAX6721UTZWD3+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6721UTZWD3+, 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 MAX6721UTZWD3+ part is unused and in its original packaging.
Return procedure for MAX6721UTZWD3+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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