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Analog Devices Inc./Maxim Integrated MAX821TUS+T
- Part No.:
- MAX821TUS+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX821TUS+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT143-4
- Quantity:
- Payment:
- Shipping:
Inventory:2,660
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Product details
Overview
MAX821TUS+T from Maxim Integrated is an active-low microprocessor supervisory circuit in SOT143-4 package, monitoring +3.08V supply with ±1.5% reset threshold accuracy, 2.5µA quiescent current, and pin-selectable reset timeout (1ms max / 20ms min / 100ms min). It ensures reliable power-on reset for battery-powered controllers and portable instrumentation.
For engineers reviewing the MAX821TUS+T datasheet, MAX821TUS+T pinout, MAX821TUS+T application, or MAX821TUS+T equivalent, this page delivers verified electrical parameters, thermal performance across –40°C to +125°C, SRT input configuration logic, RESET output behavior down to VCC = 1V, and validated alternative supervisory ICs for 3V system designs.
Technical Context
The MAX821TUS+T implements a precision bandgap-based voltage comparator with hysteresis-free threshold detection at 3.08V nominal, coupled to a temperature-stable monostable timer whose timeout is set solely by the SRT pin state (GND/VCC/floating). Its internal architecture guarantees RESET remains asserted during VCC brownouts and reasserts immediately upon any VCC dip below threshold.
Designed for low-power embedded systems, it features transient immunity against VCC glitches ≤12µs at 100mV overdrive, operates with no external components, and maintains functional RESET output validity down to VCC = 1V - critical for safe µP initialization in deep-battery-discharge scenarios.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Reset Threshold | 3.08V ±1.5% - precisely matches 3.3V rail tolerance for robust brownout detection without false triggers |
| Supply Current | 2.5µA typical - enables multi-year operation in coin-cell–powered devices |
| Reset Timeout Options | 1ms (max), 20ms (min), or 100ms (min) - selected via SRT pin connection, supporting fast-boot or legacy-timing requirements |
| Operating Temperature | –40°C to +125°C - qualified for automotive under-hood and industrial control environments |
| VCC Validity Range | RESET guaranteed low for VCC ≥1V - ensures deterministic µP reset state even during deep discharge |
| Transient Immunity | Rejects VCC glitches ≤12µs at 100mV overdrive - prevents spurious resets from switching noise or ESD coupling |
Pinout & Package
SOT143-4 surface-mount package (1.3mm × 2.1mm × 0.95mm), lead-free, RoHS-compliant, thermally optimized for high-density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 GND | Ground reference | Return path for internal comparator and timer; must be low-impedance to avoid noise-induced reset errors |
| 2 RESET | Active-low reset output | Open-drain compatible; sinks ≥1.2mA at VTH(MIN); asserts low until timeout completes after VCC recovery |
| 3 SRT | Set Reset Timeout input | Three-state logic: GND → 1ms, VCC → 20ms, floating → 100ms; <200pF loading required for reliable 100ms mode |
| 4 VCC | Supply input | Monitored voltage rail; absolute max 6.0V; supports operation down to 1.0V while maintaining RESET validity |
Key Features
| Feature | Design Value |
|---|---|
| Pin-selectable reset timeout | Eliminates need for external RC timing networks or firmware configuration - reduces BOM count and layout complexity |
| 3.08V precision threshold | Matches common 3.3V LDO output tolerances, enabling direct integration without resistor dividers or calibration |
| 2.5µA supply current | Enables always-on supervision in energy-harvesting and ultra-low-power IoT nodes without compromising battery life |
| VCC = 1V RESET validity | Guarantees µP enters known reset state before supply collapses completely - prevents undefined execution on residual charge |
| Transient-immune comparator | Rejects short-duration supply noise without requiring additional filtering capacitors - saves board space and cost |
Applications
| Bar-Code Scanners | Portable Medical Devices |
|---|---|
Use Scenario: Handheld scanner powered by single Li-ion cell with dynamic load switching causing VCC droop. IC Role / Device Role / Timing Role: Supervisory IC asserting active-low RESET to halt MCU during brownout and hold reset for 20ms after recovery. Use Value: Prevents corrupted scan data and flash memory writes during unstable power conditions using factory-set 20ms timeout. | Use Scenario: Battery-operated glucose meter requiring guaranteed startup sequence after cold storage (-20°C). IC Role / Device Role / Timing Role: Voltage monitor ensuring µC initializes only when 3.3V rail is stable above 3.08V, with 100ms delay for analog sensor settling. Use Value: Eliminates need for software-based power-good polling, reducing firmware complexity and boot time uncertainty. |
| Industrial PLC I/O Modules | Smart Energy Meters |
Use Scenario: DIN-rail mounted controller exposed to wide ambient temperatures (-40°C to +85°C) and conducted EMI. IC Role / Device Role / Timing Role: Reset supervisor validating 3.3V logic rail integrity and asserting RESET during line transients or brownouts. Use Value: Maintains deterministic reset behavior across full industrial temperature range with ±1.5% threshold stability. | Use Scenario: Revenue-grade meter with tamper-detection circuitry requiring fail-safe reset during AC mains interruption. IC Role / Device Role / Timing Role: Monitors backup supercapacitor voltage and triggers 1ms reset pulse to capture last valid kWh reading before power loss. Use Value: Enables ultra-fast, hardware-guaranteed reset response without CPU intervention - critical for regulatory compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage supervisor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS3808G30DBVR | Fixed 3.0V threshold, 200ms default timeout (adjustable via external capacitor), 1.1µA IQ | Lacks pin-selectable timeout; requires external cap for timing; better for ultra-low-IQ designs where fixed delay suffices | Select when lowest possible quiescent current is prioritized over pin-strapped flexibility |
| ADM6705ARTZ-R7 | 3.08V threshold, 200ms timeout, push-pull RESET output, -40°C to +125°C rating | Push-pull (not open-drain) RESET; no SRT pin - fixed timing only; higher ICC (8µA) | Choose when driving heavy capacitive loads or level-shifting without external pull-up is required |
Compared with TPS3808G30DBVR and ADM6705ARTZ-R7, the MAX821TUS+T uniquely combines pin-selectable timing, 2.5µA IQ, and guaranteed RESET validity down to VCC = 1V - making it optimal for space-constrained, battery-critical 3V systems needing hardware-configurable reset behavior.
Availability
MAX821TUS+T is available at Aetrix Electronics and suitable for bar-code scanners, portable medical devices, industrial PLC I/O modules, smart energy meters, and battery-powered instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX821TUS+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, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.
The MAX821/MAX822 product line delivers highly integrated, low-power supervisory circuits targeting cost-sensitive and space-constrained embedded systems requiring guaranteed power-on reset and brownout protection.
FAQ
What is the exact reset threshold voltage for MAX821TUS+T?
The MAX821TUS+T has a nominal reset threshold of 3.08V with ±1.5% accuracy over –40°C to +125°C. This value is laser-trimmed during manufacturing and specified in the Electrical Characteristics table under "VTH Reset Threshold" for ordering option "T". The MAX821TUS+T is explicitly designated for 3.08V monitoring in the official Maxim ordering guide.
How does the SRT pin configure the reset timeout on MAX821TUS+T?
The SRT pin on MAX821TUS+T selects reset timeout via three states: connect to GND for 1ms (maximum), connect to VCC for 20ms (minimum), or leave unconnected for 100ms (minimum). Capacitive loading on SRT must remain below 200pF to ensure reliable 100ms operation. This pin-strapping eliminates external timing components and enables hardware-defined reset timing in MAX821TUS+T.
Is MAX821TUS+T compatible with 3.3V systems?
Yes, MAX821TUS+T is specifically designed for 3.3V systems: its 3.08V reset threshold sits safely within the typical ±5% tolerance of a 3.3V supply (3.135V–3.465V), ensuring reliable detection of brownout conditions while avoiding false triggers during normal regulation. The MAX821TUS+T datasheet confirms compatibility with +3V to +5V supplies.
Does MAX821TUS+T provide reset assertion during power-down?
Yes, MAX821TUS+T asserts RESET low whenever VCC falls below 3.08V - including during power-down. The device guarantees RESET remains valid (low) down to VCC = 1V, ensuring the microprocessor stays held in reset until supply collapses beyond functional levels. This behavior is explicitly documented in the "Guaranteed RESET Valid to VCC = 1V" feature and confirmed in the Detailed Description section of the MAX821TUS+T datasheet.
What package type and footprint does MAX821TUS+T use?
MAX821TUS+T uses the SOT143-4 package (1.3mm × 2.1mm × 0.95mm), a 4-pin surface-mount outline with GND, RESET, SRT, and VCC terminals in standard top-view configuration. The "+T" suffix denotes lead-free, RoHS-compliant packaging. This compact footprint is widely supported in PCB design tools and matches industry-standard SOT-143 land patterns.
MAX821TUS+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- TO-253-4, TO-253AA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 3.08V
- 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-143-4
MAX821TUS+T FAQ
1.How can I place an order for MAX821TUS+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX821TUS+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 MAX821TUS+T reliable?
The price and inventory of MAX821TUS+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX821TUS+T is usually 5 days.
3.What payment methods are accepted for MAX821TUS+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX821TUS+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX821TUS+T?
MAX821TUS+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX821TUS+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 MAX821TUS+T?
For technical support, including MAX821TUS+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX821TUS+T requirements.
6.How does Aetrix verify that MAX821TUS+T is sourced from the original manufacturer or authorized distributors?
All MAX821TUS+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 MAX821TUS+T meets industry standards.
7.What is the process for return or replacement of MAX821TUS+T?
All MAX821TUS+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX821TUS+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 MAX821TUS+T part is unused and in its original packaging.
Return procedure for MAX821TUS+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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