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Analog Devices Inc./Maxim Integrated MAX821RUS
- Part No.:
- MAX821RUS
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- TO-253-4, TO-253AA
- Datasheet:
-
MAX821RUS.pdf
- Description:
- IC SUPERVISOR MPU VOLT MONITOR
- Quantity:
- Payment:
- Shipping:
Inventory:3,360
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Product details
Overview
MAX821RUS from Maxim Integrated is an active-low microprocessor supervisory IC in SOT143-4 package, designed to monitor +2.63V supply rails and assert a guaranteed logic-low RESET output down to VCC = 1V. It provides pin-selectable power-on reset timeout delays of 1ms (max), 20ms (min), or 100ms (min) and draws only 2.5µA supply current. It is used in portable battery-powered equipment requiring reliable brownout detection and controlled system initialization.
For engineers reviewing the MAX821RUS datasheet, MAX821RUS pinout, MAX821RUS application, or MAX821RUS equivalent, this page delivers verified technical context, precise reset threshold behavior, temperature-stable timeout timing, transient immunity specs, and validated alternative options for 2.63V-supply monitoring systems.
Technical Context
The MAX821RUS implements a precision voltage comparator with 2.63V nominal reset threshold (±1.5% over -40°C to +125°C), coupled to a digital timeout timer whose delay is set by the SRT pin state (GND/VCC/unconnected). Its reset assertion is immune to fast VCC transients ≤12µs at 100mV overdrive.
It operates across full industrial temperature range (-40°C to +125°C) with guaranteed RESET validity down to VCC = 1V and exhibits 30ppm/°C reset threshold tempco. The device requires no external components and interfaces directly to µP reset inputs without pull-up/pull-down biasing under normal operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.63V ±1.5% - precisely matches 2.63V supply rail monitoring requirement |
| Supply Current | 2.5µA typical - enables multi-year battery life in portable equipment |
| Operating Temp | -40°C to +125°C - supports automotive under-hood and industrial control environments |
| Reset Timeout Options | 1ms (max), 20ms (min), 100ms (min) - selectable via SRT pin connection state |
| VCC Validity Range | 1.0V to 5.5V - ensures RESET remains valid during deep brownout recovery |
| Transient Immunity | 12µs max glitch duration at 100mV overdrive - prevents false resets from noise |
| Reset Output Type | Active-low open-drain - compatible with standard µP reset inputs requiring low-active assertion |
Pinout & Package
SOT143-4 surface-mount package (3.0mm × 1.6mm × 1.1mm), lead-free option available (suffix +T), JEDEC-compliant footprint per drawing 21-0052.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 GND | Ground reference | Return path for internal comparator and output stage; must be low-impedance |
| 2 RESET | Active-low reset output | Open-drain output asserted low during VCC < 2.63V and for selected timeout after recovery |
| 3 SRT | Set Reset Timeout input | Logic input: GND → 1ms, VCC → 20ms, unconnected → 100ms; <200pF loading required for 100ms mode |
| 4 VCC | Supply voltage input | Monitored rail input; powers internal circuitry and defines reset threshold reference |
Key Features
| Feature | Design Value |
|---|---|
| Precision 2.63V threshold | Guaranteed ±1.5% accuracy over full temperature range enables exact match to 2.63V LDO outputs |
| Ultra-low 2.5µA supply current | Reduces quiescent power draw by >90% vs. legacy reset ICs, critical for coin-cell applications |
| Three-mode pin-selectable timeout | Eliminates need for external RC networks or configuration resistors-reduces BOM count and layout area |
| RESET valid to VCC = 1V | Ensures deterministic reset state during deep brownout and battery depletion scenarios |
| 200pF SRT pin capacitance limit | Defines maximum allowable PCB trace length/coupling to prevent unintended timeout mode selection |
Applications
| Bar-Code Scanners | Portable Medical Devices |
|---|---|
Use Scenario: Handheld scanner powered by single Li-ion cell with 2.63V LDO regulator. IC Role / Device Role / Timing Role: Monitors LDO output and asserts RESET until stable 2.63V is confirmed, then holds reset for 20ms to allow MCU clock stabilization. Use Value: Prevents erratic boot sequence caused by marginal LDO startup; eliminates need for discrete RC reset network. | Use Scenario: Battery-powered glucose meter operating from 2.63V regulated rail with strict low-power requirements. IC Role / Device Role / Timing Role: Supervises power rail integrity and generates clean, glitch-immune reset pulse during battery insertion or voltage sag. Use Value: 2.5µA quiescent current extends battery life beyond 2 years; 1V VCC validity ensures reset remains asserted through full discharge curve. |
| Industrial Sensor Nodes | Smart Utility Meters |
Use Scenario: Remote environmental sensor node using ultra-low-power MCU and 2.63V system rail. IC Role / Device Role / Timing Role: Detects brownout events on 2.63V supply and triggers controlled MCU reset with 100ms timeout to accommodate slow-starting peripherals. Use Value: Pin-selectable 100ms delay avoids premature release of reset before analog front-end stabilizes; -40°C to +125°C rating ensures field reliability. | Use Scenario: AMI smart meter with 2.63V real-time clock and metrology subsystem. IC Role / Device Role / Timing Role: Provides fail-safe reset initiation when main 2.63V backup rail dips below threshold during power interruption. Use Value: 30ppm/°C tempco maintains threshold stability across wide ambient range; transient immunity prevents false resets from EMI-coupled noise. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX822RUS | Identical reset threshold (2.63V), but features active-high RESET output | Requires inverted reset logic on µP side; not drop-in compatible with active-low reset inputs | Select MAX822RUS only when target µP accepts active-high reset assertion |
| TPS3808G12DBVR | 2.63V threshold with 2% tolerance, 1.8µA IQ, fixed 200ms timeout (no pin select) | Lacks pin-selectable timeout; requires external capacitor for adjustable delay; different SOT-23-5 footprint | Choose only if 200ms fixed delay suffices and board layout allows SOT-23-5 rework |
Compared with MAX821RUS, MAX822RUS offers identical monitoring performance but inverted reset polarity-requiring µP interface validation-while TPS3808G12DBVR trades pin-selectable flexibility for lower quiescent current and fixed timing, necessitating PCB redesign due to incompatible package and pin count.
Availability
MAX821RUS is available at Aetrix Electronics and suitable for portable medical devices, industrial sensor nodes, bar-code scanners, and smart utility meters requiring stable component supply with guaranteed long-term availability.
Supply support for MAX821RUS 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, automotive, communications, and computing markets.
The MAX821/MAX822 product line delivers compact, low-power microprocessor supervisory ICs optimized for precise voltage monitoring and configurable reset timing in space-constrained, battery-sensitive applications.
FAQ
What is the exact reset threshold voltage of the MAX821RUS and how tightly is it specified?
The MAX821RUS has a nominal reset threshold of 2.63V, with a guaranteed tolerance of ±1.5% over the full operating temperature range (-40°C to +125°C). This specification is confirmed in the Electrical Characteristics table under "VTH" parameter for MAX82_R suffix parts. The tight tolerance ensures reliable detection of 2.63V supply rail faults without false triggering or missed events.
How does the SRT pin configure the reset timeout delay on the MAX821RUS?
The SRT pin on the MAX821RUS selects one of three reset timeout periods: connect SRT to GND for 1ms (maximum), connect to VCC for 20ms (minimum), or leave unconnected for 100ms (minimum). The datasheet specifies that capacitive loading on SRT must remain below 200pF when left unconnected to ensure correct 100ms mode selection. This pin-based configuration eliminates external timing components.
Does the MAX821RUS maintain valid RESET output down to VCC = 0V?
No-the MAX821RUS guarantees RESET output validity only down to VCC = 1V. Below 1V, the RESET output becomes high-impedance and may float. For applications requiring asserted reset down to 0V, a 100kΩ pull-down resistor on the RESET pin is recommended, as documented in the Applications Information section of the MAX821/MAX822 datasheet.
What is the supply current consumption of the MAX821RUS and under what conditions is it measured?
The MAX821RUS draws 2.5µA typical supply current (ICC), measured at TA = +25°C, VCC = 5.5V, and IOUT = 0. This ultra-low quiescent current is maintained across the full temperature range (-40°C to +125°C), with normalized supply current varying less than ±10% over temperature, enabling multi-year operation in battery-powered systems.
Can the MAX821RUS be used with 3.3V or 5V supply rails, or is it limited to 2.63V systems?
The MAX821RUS is specifically calibrated for 2.63V supply monitoring and should not be used to supervise 3.3V or 5V rails. Other variants in the MAX821 family-such as MAX821TUS (3.08V), MAX821SUS (2.93V), and MAX821LUS (4.38V)-are designated for different thresholds. Using MAX821RUS on higher rails would result in premature or continuous reset assertion due to threshold mismatch.
MAX821RUS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- TO-253-4, TO-253AA
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Power Supply Monitor
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.63V
- Output:
- -
- Reset:
- Active Low
- Reset Timeout:
- 100ms Minimum
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-4
MAX821RUS FAQ
1.How can I place an order for MAX821RUS through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX821RUS 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 MAX821RUS reliable?
The price and inventory of MAX821RUS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX821RUS is usually 5 days.
3.What payment methods are accepted for MAX821RUS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX821RUS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX821RUS?
MAX821RUS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX821RUS 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 MAX821RUS?
For technical support, including MAX821RUS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX821RUS requirements.
6.How does Aetrix verify that MAX821RUS is sourced from the original manufacturer or authorized distributors?
All MAX821RUS 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 MAX821RUS meets industry standards.
7.What is the process for return or replacement of MAX821RUS?
All MAX821RUS units undergo pre-shipment inspection (PSI). If there is an issue with MAX821RUS, 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 MAX821RUS part is unused and in its original packaging.
Return procedure for MAX821RUS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX821RUS Tags
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MIC826SYMT-TR
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APX803L20-29SA-7
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