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Analog Devices Inc./Maxim Integrated MAX821PUS+T
- Part No.:
- MAX821PUS+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX821PUS+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT143-4
- Quantity:
- Payment:
- Shipping:
Inventory:1,955
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Product details
Overview
MAX821PUS+T from Maxim Integrated is an active-low microprocessor supervisory circuit in SOT143-4 package, monitoring +4.00V supply voltage 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-on/brownout reset assertion in portable µP systems.
For engineers reviewing the MAX821PUS+T datasheet, MAX821PUS+T pinout, MAX821PUS+T application, or MAX821PUS+T equivalent, key selection criteria include guaranteed RESET validity down to VCC = 1V, immunity to fast VCC transients (<12µs at 100mV overdrive), SRT pin configuration logic (GND/VCC/floating), and compatibility with 3V–5V digital systems requiring low-power, temperature-stable reset supervision.
Technical Context
The MAX821PUS+T implements a precision bandgap-based voltage comparator with 30ppm/°C tempco to detect VCC falling below 4.00V (±1.5%), asserting active-low RESET until VCC recovers and the internal timer expires. Its SRT input directly configures timeout via discrete logic levels-GND selects 1ms (max), VCC selects 20ms (min), and open selects 100ms (min)-with <200pF capacitive loading requirement for stable 100ms mode.
Designed for fail-safe operation, the device guarantees RESET remains valid (low) for VCC ≥1V and ignores transients ≤12µs when VCC dips 100mV below threshold. It draws only 2.5µA at +25°C and maintains full functionality across automotive-grade temperature range (-40°C to +125°C) without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.00V ±1.5% - precisely matches +4V supply rails; ensures reset asserts before downstream logic fails |
| Supply Current | 2.5µA typical at +25°C - enables multi-year battery life in portable equipment |
| Operating Temp | -40°C to +125°C - supports under-hood automotive and industrial embedded environments |
| Reset Timeout | Pin-selectable: 1ms (max), 20ms (min), or 100ms (min) - configurable for fast-boot or legacy µP timing requirements |
| VCC Validity | RESET guaranteed low for VCC ≥1V - ensures deterministic state during deep brownout recovery |
| Transient Immunity | Rejects VCC glitches ≤12µs at 100mV overdrive - prevents spurious resets from noise or coupling |
| Package | SOT143-4 - 1.3mm × 1.3mm footprint; compatible with high-density PCB layouts |
Pinout & Package
SOT143-4 surface-mount package: 1.3mm × 1.3mm body, 0.95mm height, gull-wing leads, JEDEC MO-178AC compliant. Thermal resistance θJA = 250°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Ground reference | Return path for internal comparator and output driver; must be low-impedance connection to system ground plane |
| RESET (Pin 2) | Active-low reset output | Open-drain NMOS output; requires external pull-up; sinks ≥1.2mA at VTH(MIN) to guarantee logic low |
| SRT (Pin 3) | Set Reset Timeout input | Three-state logic control: GND = 1ms, VCC = 20ms, floating = 100ms; <200pF loading required for stable 100ms mode |
| VCC (Pin 4) | Supply voltage input | Accepts +3V to +5.5V; powers internal circuitry and defines reset threshold reference point |
Key Features
| Feature | Design Value |
|---|---|
| Pin-selectable reset timeout | Eliminates need for external RC timing networks; supports rapid prototyping across boot-time requirements |
| Guaranteed RESET down to VCC = 1V | Ensures µP remains held in reset during deep undervoltage conditions where internal logic is nonfunctional |
| 30ppm/°C reset threshold tempco | Maintains tight threshold tolerance across full operating temperature range without calibration |
| No external components required | Reduces BOM count, PCB area, and assembly cost; improves long-term reliability by removing passive drift sources |
| Immunity to fast VCC transients | Prevents false resets from ESD, switching noise, or crosstalk-critical in noisy industrial environments |
Applications
| Bar-Code Scanners | Portable Medical Devices |
|---|---|
Use Scenario: Handheld scanners powered by single-cell Li-ion batteries experiencing voltage sag during motor activation or laser firing. IC Role / Device Role / Timing Role: Supervisory IC asserting active-low reset to halt µP execution until battery voltage recovers above 4.00V. Use Value: Prevents corrupted scan data or firmware crashes caused by brownout-induced µP instability during transient load events. | Use Scenario: Battery-powered glucose meters or pulse oximeters requiring guaranteed reset during cold-start or low-battery shutdown. IC Role / Device Role / Timing Role: Voltage monitor holding µC in reset until regulated 4.00V rail stabilizes post-power-up, with 100ms timeout ensuring complete initialization. Use Value: Enables FDA-compliant deterministic boot sequence with no risk of partial register initialization or memory corruption. |
| Industrial PLC I/O Modules | Automotive Body Control Units |
Use Scenario: DIN-rail mounted controllers exposed to wide ambient temperatures (-40°C to +85°C) and conducted EMI on 24V DC input rails. IC Role / Device Role / Timing Role: Reset supervisor detecting undervoltage on local 5V LDO output, asserting reset with 20ms timeout to synchronize with fieldbus startup timing. Use Value: Eliminates watchdog timeouts and communication faults during cold-cranking or alternator load-dump recovery. | Use Scenario: Under-dash modules subjected to thermal cycling and load-dump transients on 12V supply lines. IC Role / Device Role / Timing Role: Active-low reset generator monitoring 4.00V domain derived from vehicle battery; SRT tied to VCC for 20ms minimum timeout. Use Value: Meets ISO 16750-2 pulse 4a/b immunity requirements by rejecting sub-15µs transients while asserting clean reset after sustained undervoltage. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage supervisor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS3808G12DBVR | Fixed 1.2V threshold; 200ms factory-programmed timeout; 1.5µA supply current | Targets ultra-low-voltage logic domains; lacks pin-selectable timeout and 4.00V threshold | Select only if system uses 1.2V core rail and fixed long timeout suffices |
| ADM6705LAKSZ-REEL7 | 4.00V threshold; 200ms fixed timeout; 3.5µA supply current; operates down to -40°C | Higher quiescent current; no SRT configurability; requires external capacitor for manual reset | Choose when pin count allows extra capacitor and design prioritizes second-source availability over timeout flexibility |
Compared with TPS3808G12DBVR and ADM6705LAKSZ-REEL7, the MAX821PUS+T uniquely combines 4.00V precision threshold, pin-selectable timeout (1ms/20ms/100ms), and sub-3µA supply current in a 4-pin SOT143-enabling compact, low-power, and timing-flexible reset supervision where adjustable boot timing is critical.
Availability
MAX821PUS+T is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC I/O modules, and automotive body control units requiring stable component supply with guaranteed lead-free compliance and extended temperature support.
Supply support for MAX821PUS+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 microprocessor supervisory circuits optimized for reliable reset generation in space-constrained, battery-sensitive, and thermally demanding embedded systems.
FAQ
What is the exact reset threshold voltage for MAX821PUS+T?
The MAX821PUS+T has a nominal reset threshold of 4.00V with ±1.5% accuracy over the full -40°C to +125°C temperature range. This value is laser-trimmed during production and specified in the Ordering Information table of the official datasheet. The threshold remains stable due to a 30ppm/°C tempco, making it suitable for applications requiring precise 4V supply monitoring without external calibration.
How does the SRT pin configure the reset timeout on MAX821PUS+T?
The SRT pin on MAX821PUS+T sets the reset timeout period using three discrete 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 when floating to ensure reliable 100ms selection. Driving SRT with an external signal requires <500µs edge transition times to avoid unintended timeout modes.
Is MAX821PUS+T compatible with 3.3V systems?
No-MAX821PUS+T is specifically trimmed for 4.00V threshold and is not rated for reliable operation in 3.3V systems. For 3.3V monitoring, use MAX821TUS+T (3.08V threshold) or MAX821SUS+T (2.93V threshold). Attempting to use MAX821PUS+T in a 3.3V system will cause premature or continuous reset assertion since VCC never reaches the 4.00V threshold.
Does MAX821PUS+T require an external pull-up resistor on the RESET pin?
Yes-MAX821PUS+T features an open-drain active-low RESET output and requires an external pull-up resistor to VCC (typically 10kΩ to 100kΩ) to establish a valid high level when reset is inactive. Without this resistor, the RESET line floats, risking indeterminate logic states at the microprocessor's reset input and potential startup failures.
What is the minimum VCC voltage at which MAX821PUS+T guarantees RESET validity?
The MAX821PUS+T guarantees the RESET output remains a valid logic low for VCC ≥1V. Below 1V, the output transitions to high-impedance (open-circuit) behavior. For applications requiring RESET validity down to 0V, a 100kΩ pull-down resistor from RESET to GND is recommended to prevent floating states during deep brownout conditions.
MAX821PUS+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:
- 4V
- 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
MAX821PUS+T FAQ
1.How can I place an order for MAX821PUS+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX821PUS+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 MAX821PUS+T reliable?
The price and inventory of MAX821PUS+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX821PUS+T is usually 5 days.
3.What payment methods are accepted for MAX821PUS+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX821PUS+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX821PUS+T?
MAX821PUS+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX821PUS+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 MAX821PUS+T?
For technical support, including MAX821PUS+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX821PUS+T requirements.
6.How does Aetrix verify that MAX821PUS+T is sourced from the original manufacturer or authorized distributors?
All MAX821PUS+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 MAX821PUS+T meets industry standards.
7.What is the process for return or replacement of MAX821PUS+T?
All MAX821PUS+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX821PUS+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 MAX821PUS+T part is unused and in its original packaging.
Return procedure for MAX821PUS+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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