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Analog Devices Inc./Maxim Integrated MAX821SUS+T
- Part No.:
- MAX821SUS+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX821SUS+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT143-4
- Quantity:
- Payment:
- Shipping:
Inventory:8,141
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Product details
Overview
MAX821SUS+T from Maxim Integrated is an active-low microprocessor supervisory circuit in SOT143-4 package, monitoring +2.93V supply with ±1.5% threshold accuracy over -40°C to +125°C, 2.5µA quiescent current, and pin-selectable reset timeout (1ms max / 20ms min / 100ms min) for reliable power-up sequencing in battery-powered controllers and portable instrumentation.
For engineers reviewing the MAX821SUS+T datasheet, MAX821SUS+T pinout, MAX821SUS+T application, or MAX821SUS+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = 1V, immunity to fast VCC transients (<12µs at 100mV overdrive), SRT input configuration options, and compatibility with 3V µP systems requiring precise brownout detection.
Technical Context
The MAX821SUS+T implements a precision bandgap-based voltage comparator with internal hysteresis and a temperature-compensated reset threshold of 2.93V (±1.5%), enabling deterministic assertion of active-low RESET during VCC brownout or power-down. Its SRT pin directly configures the internal monostable timeout period without external components.
Designed for embedded reliability, it features 30ppm/°C tempco, operates from 1.0V to 5.5V VCC, guarantees RESET state integrity down to VCC = 1V, and rejects transients via comparator overdrive filtering-critical for noisy 3V rail environments in handheld devices.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.93V ±1.5% - ensures reliable assertion before 3V system ICs drop below minimum operating voltage |
| Supply Current | 2.5µA typical - enables multi-year operation on coin-cell batteries in portable instruments |
| Operating Temp | -40°C to +125°C - supports industrial and automotive under-hood applications without derating |
| Reset Timeout | Pin-selectable: 1ms (max), 20ms (min), or 100ms (min) - matches µP initialization timing requirements across platforms |
| VCC Range | 1.0V to 5.5V - allows valid RESET output assertion even during deep brownout recovery |
| Transient Immunity | Rejects <12µs negative VCC glitches at 100mV overdrive - prevents spurious resets in electrically noisy environments |
| Threshold Tempco | 30ppm/°C - maintains tight voltage margin across full temperature range without calibration |
Pinout & Package
SOT143-4 surface-mount package (1.3mm × 2.1mm × 0.95mm), lead-free, RoHS-compliant, with exposed pad not connected internally.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Return path for internal comparator and RESET driver; must be low-impedance for noise immunity |
| RESET (Pin 2) | Active-low reset output | Open-drain NMOS output; sinks ≥1.2mA at VTH(MIN); requires external pull-up for logic-high level |
| SRT (Pin 3) | Set Reset Timeout input | Three-state control: GND = 1ms, VCC = 20ms, open = 100ms; <200pF loading required for 100ms mode |
| VCC (Pin 4) | Supply voltage input | Power source for internal circuitry; also serves as monitored rail when used with 3V systems |
Key Features
| Feature | Design Value |
|---|---|
| Pin-selectable reset timeout | Eliminates need for external RC timing networks-reduces BOM count and layout area in space-constrained designs |
| Guaranteed RESET down to VCC = 1V | Ensures deterministic reset assertion during deep brownout recovery, preventing µP lockup in low-VCC states |
| No external components required | Reduces design validation effort and improves long-term reliability by removing passive component failure modes |
| 30ppm/°C threshold tempco | Maintains consistent reset margin across temperature extremes-critical for unregulated battery-powered systems |
| 2.5µA supply current | Enables integration into always-on monitoring circuits without compromising battery life in portable equipment |
Applications
| Bar-Code Scanners | Portable Medical Instruments |
|---|---|
Use Scenario: Handheld scanner powered by single Li-ion cell with dynamic load switching causing 3V rail sag. IC Role / Device Role / Timing Role: Voltage monitor asserting active-low RESET to halt µP execution until VCC recovers above 2.93V and sustains 100ms stable window. Use Value: Prevents corrupted scan data and firmware crashes during intermittent power dips caused by motor activation. | Use Scenario: Battery-operated glucose meter with cold-temperature operation down to -20°C. IC Role / Device Role / Timing Role: Brownout detector ensuring µC reset remains asserted until regulated 3V rail stabilizes after cold-start battery voltage rise. Use Value: Guarantees safe initialization sequence despite reduced battery voltage and increased µC VDD(min) at low temperature. |
| Industrial PLC I/O Modules | Smart Energy Meters |
Use Scenario: DIN-rail mounted controller exposed to wide ambient temperature swings (-40°C to +85°C). IC Role / Device Role / Timing Role: Supervisory circuit validating 3.3V logic rail integrity and providing 20ms reset hold time after power restoration. Use Value: Eliminates need for external temperature compensation while maintaining ±1.5% threshold accuracy across full industrial range. | Use Scenario: Tamper-resistant meter with isolated power domains and frequent AC line interruptions. IC Role / Device Role / Timing Role: Dual-role supervisor detecting both main 3V supply brownout and backup supercapacitor discharge threshold. Use Value: Enables seamless switchover to backup power with deterministic 1ms reset assertion upon primary rail collapse. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLV803EB29DPWR | Fixed 2.93V threshold, no SRT pin; 350ms reset timeout; 0.5µA IQ; SOT-23-3 package | Lacks pin-selectable timeout; requires PCB change for timing adjustment; smaller footprint but no timeout flexibility | Select when ultra-low IQ dominates design priority and fixed 350ms timeout is acceptable |
| TPS3808G12DBVR | Adjustable threshold via external resistor divider; 200ms default timeout; 1.1µA IQ; SOT-23-6 package | Requires two external resistors; supports custom thresholds but adds BOM and layout complexity | Select when system needs non-standard reset voltage (e.g., 2.85V) and can accommodate extra passives |
Compared with TLV803EB29DPWR and TPS3808G12DBVR, the MAX821SUS+T uniquely delivers factory-trimmed 2.93V accuracy with zero external components and field-configurable timeout-all in a 4-pin SOT143, making it optimal for cost-sensitive, space-constrained 3V µP systems where timing flexibility matters.
Availability
MAX821SUS+T is available at Aetrix Electronics and suitable for portable medical instruments, industrial PLC I/O modules, smart energy meters, and bar-code scanners requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for MAX821SUS+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 high-performance analog and mixed-signal semiconductor solutions for industrial, communications, computing, and consumer markets.
The MAX821 series targets cost-sensitive, low-power µP supervision in portable and harsh-environment applications, emphasizing zero-component simplicity, wide temperature operation, and deterministic reset timing.
FAQ
What is the exact reset threshold voltage of the MAX821SUS+T and how is it specified?
The MAX821SUS+T has a nominal reset threshold of 2.93V with ±1.5% accuracy over the full -40°C to +125°C temperature range. This value is factory-trimmed and guaranteed-not typical-meaning every unit meets this specification without external calibration. The threshold is referenced to the VCC pin and remains stable due to 30ppm/°C tempco, making it suitable for unregulated 3V battery systems where voltage drift must be tightly controlled.
How does the SRT pin configure the reset timeout delay on the MAX821SUS+T?
The SRT pin on the MAX821SUS+T selects one of three factory-programmed timeout periods: connect SRT to GND for 1ms (maximum), to VCC for 20ms (minimum), or leave it unconnected for 100ms (minimum). Capacitive loading on SRT must stay below 200pF when left open to ensure correct 100ms operation. Driving SRT with an external signal is possible but requires sub-500µs edge rates to avoid unintended timeout selection.
Does the MAX821SUS+T guarantee valid RESET output behavior when VCC drops below 1V?
Yes-the MAX821SUS+T guarantees that its active-low RESET output remains a valid logic low down to VCC = 1V. Below 1V, the output transitions to a high-impedance state (open circuit). For applications requiring RESET validity all the way to 0V, a 100kΩ pull-down resistor on the RESET pin is recommended to prevent floating logic levels during deep brownout conditions.
What package type and dimensions does the MAX821SUS+T use, and is it RoHS-compliant?
The MAX821SUS+T uses the SOT143-4 package: 1.3mm × 2.1mm × 0.95mm body size with gull-wing leads. It is lead-free and RoHS-compliant, with top marking "BC_ _" (where "BC" identifies the MAX821SUS variant). The package has no internal connection to the exposed thermal pad, which may be left floating or grounded per PCB thermal requirements.
Can the MAX821SUS+T be used with 3.3V microcontrollers, and what interface considerations apply?
Yes-the MAX821SUS+T is fully compatible with 3.3V µCs. Its 2.93V reset threshold provides appropriate margin above typical 3.3V regulator dropout, and its open-drain RESET output requires only a pull-up resistor to the µC's I/O voltage (e.g., 3.3V). No level-shifting is needed. Ensure the pull-up value (typically 4.7kΩ–10kΩ) balances rise time and power consumption, especially in battery-powered systems.
MAX821SUS+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:
- 2.93V
- 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
MAX821SUS+T FAQ
1.How can I place an order for MAX821SUS+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX821SUS+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 MAX821SUS+T reliable?
The price and inventory of MAX821SUS+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX821SUS+T is usually 5 days.
3.What payment methods are accepted for MAX821SUS+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX821SUS+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX821SUS+T?
MAX821SUS+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX821SUS+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 MAX821SUS+T?
For technical support, including MAX821SUS+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX821SUS+T requirements.
6.How does Aetrix verify that MAX821SUS+T is sourced from the original manufacturer or authorized distributors?
All MAX821SUS+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 MAX821SUS+T meets industry standards.
7.What is the process for return or replacement of MAX821SUS+T?
All MAX821SUS+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX821SUS+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 MAX821SUS+T part is unused and in its original packaging.
Return procedure for MAX821SUS+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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