My Inquiry
My Account
Analog Devices Inc./Maxim Integrated MAX6821LUK+
- Part No.:
- MAX6821LUK+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SC-74A, SOT-753
- Datasheet:
-
MAX6821LUK+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,385
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
MAX6821LUK+ from Maxim Integrated is a low-voltage microprocessor supervisory circuit in a 5-pin SOT23 package, providing voltage monitoring (4.63V threshold), 140ms minimum reset timeout, and 1.6s watchdog timer functionality with push-pull RESET output. It asserts reset during power-up, brownout, or software fault conditions and supports manual reset via MR input - used in set-top boxes, embedded controllers, and portable battery-powered equipment.
For engineers reviewing the MAX6821LUK+ datasheet, MAX6821LUK+ pinout, MAX6821LUK+ application, or MAX6821LUK+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative options for µP reset and watchdog system design.
Technical Context
The MAX6821LUK+ integrates three core functions: precision voltage monitoring with ±1.5% threshold accuracy at 4.63V, a monostable reset generator with guaranteed 140ms–320ms timeout over –40°C to +125°C, and a watchdog timer that triggers reset if WDI remains static beyond 1.12s–2.60s. Its push-pull RESET output drives high (≥0.8×VCC) when inactive and low (≤0.4V) when asserted, supporting direct interface to µP reset inputs without external pullups.
MR input features internal 50kΩ pullup and 100ns glitch rejection; WDI accepts CMOS-level pulses as short as 50ns and clears the watchdog on any edge transition. The device operates down to VCC = +1.0V, ensuring valid reset assertion even during deep brownout conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.63V ±1.5% (L-suffix); precise brownout detection for +5V systems |
| Reset Timeout Period | 140ms min (100ms min at –40°C to +125°C); ensures µP initialization completes before release |
| Watchdog Timeout | 1.6s nominal (1.12s–2.60s over temp); detects firmware hangs in real-time embedded control loops |
| VCC Operating Range | +1.2V to +5.5V (–40°C to +125°C); supports wide-input industrial and battery-backed applications |
| RESET Output Type | Push-pull active-low; eliminates need for external pullup resistor on µP reset line |
| Supply Current | 30µA max at –40°C to +125°C (VCC = +5.5V); enables ultra-low-power operation in portable devices |
| MR Input Logic | Active-low with 50kΩ internal pullup; allows momentary switch-to-GND implementation without external components |
Pinout & Package
Package: 5-pin SOT23-5 (U5-1 outline), footprint compatible with industry-standard land pattern 21-0057, RoHS-compliant (+ suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RESET | Active-low push-pull reset output; drives low during VCC undervoltage, MR assertion, or watchdog timeout |
| 2 | GND | Ground reference for all internal circuits and reset timing; must be connected to system ground plane |
| 3 | MR | Active-low manual reset input; internally pulled up to VCC; 200ns delay from MR high-to-low to RESET assertion |
| 4 | WDI | Watchdog input; toggling within 1.6s resets internal timer; left unconnected disables watchdog function |
| 5 | VCC | Supply voltage and monitored rail; reset triggers when VCC falls below 4.63V; valid operation down to +1.0V |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed Reset Valid to VCC = +1.0V | Ensures reliable reset assertion during deep brownout or battery depletion, critical for data retention in portable equipment |
| No External Components Required | Integrates pullup resistor on MR, precision voltage reference, and timing capacitors - reduces BOM count and PCB area |
| Immunity to Short Negative VCC Transients | Withstands ≤20µs transients down to 100mV below threshold without spurious reset, improving noise robustness in noisy environments |
| Debounced Manual Reset Input | 100ns glitch rejection and internal filtering eliminate need for external RC debounce network in front-panel reset switches |
| 1.6s Watchdog Timeout with Edge-Triggered Clear | Resets on any WDI rising or falling edge - enables flexible software supervision without strict pulse-width constraints |
Applications
| Set-Top Boxes | Embedded Controllers |
|---|---|
Use Scenario: Power sequencing and firmware recovery during HDMI hot-plug or conditional access module insertion. IC Role / Device Role / Timing Role: Voltage monitor and watchdog supervisor ensuring µP reset integrity during transient power disturbances. Use Value: Prevents frozen UI states by asserting reset within 140ms of VCC dip below 4.63V and detecting hung middleware via 1.6s watchdog timeout. |
Use Scenario: Industrial PLC I/O modules requiring deterministic boot and runtime fault recovery. IC Role / Device Role / Timing Role: Primary reset controller coordinating power-on reset, manual service reset, and software hang detection. Use Value: Push-pull RESET directly drives µP reset pin without pullup; MR input enables field-service reset via front-panel button; watchdog guards against ladder logic execution stalls. |
| Portable/Battery-Powered Equipment | Intelligent Instruments |
Use Scenario: Handheld multimeters and data loggers operating from single-cell Li-ion or alkaline batteries. IC Role / Device Role / Timing Role: Low-voltage supervisor maintaining reset validity down to VCC = +1.0V during battery discharge. Use Value: Guarantees clean µP restart before brownout-induced corruption; 30µA max supply current extends battery life between calibrations. |
Use Scenario: Benchtop oscilloscopes and spectrum analyzers with FPGA-based acquisition engines. IC Role / Device Role / Timing Role: Dual-role supervisor handling both power-rail monitoring and FPGA configuration watchdog. Use Value: WDI interface monitors FPGA heartbeat signal; 4.63V threshold aligns with +5V analog supply rail; SOT23-5 footprint minimizes layout impact on dense signal-path boards. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar µP supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6822LUK+ | Open-drain RESET output instead of push-pull; identical 4.63V threshold, 140ms timeout, and 1.6s watchdog | Requires external pullup resistor; suitable for bidirectional µP reset pins (e.g., Motorola 68HC11) | Select when interfacing to µPs with shared reset buses or open-drain-compatible I/O |
| TPS3808G33DBVR | 3.3V fixed threshold, 200ms reset timeout, no watchdog timer; 1.8V–6.0V VCC range; 2.5µA quiescent current | Lacks watchdog and manual reset; optimized for ultra-low-power, single-threshold monitoring only | Select when watchdog and MR functions are unnecessary and sub-µA supply current is mandatory |
Compared with MAX6821LUK+, MAX6822LUK+ offers open-drain flexibility at the cost of an external pullup, while TPS3808G33DBVR trades away watchdog/MR capability for lower power and simpler integration in non-critical monitoring roles.
Availability
MAX6821LUK+ is available at Aetrix Electronics and suitable for set-top boxes, embedded controllers, and portable/battery-powered equipment requiring stable component supply, long-term lifecycle support, and automotive-grade temperature range (–40°C to +125°C).
Supply support for MAX6821LUK+ 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 designs high-performance analog and mixed-signal semiconductor solutions for industrial, computing, and consumer applications.
The MAX6821–MAX6825 family delivers compact, low-power µP supervisory functions targeting space-constrained embedded systems where reliability under voltage transients and software faults is critical.
FAQ
What is the exact reset threshold voltage of the MAX6821LUK+?
The MAX6821LUK+ has a factory-programmed reset threshold of 4.63V with ±1.5% tolerance over –40°C to +125°C. This value is confirmed in the Threshold Suffix Guide (L = 4.63V) and Electrical Characteristics table under VTH for MAX682_L. The device asserts RESET when VCC falls below this level and holds it for ≥140ms after VCC rises above threshold.
Does the MAX6821LUK+ include a watchdog timer, and what is its timeout period?
Yes, the MAX6821LUK+ includes a watchdog timer with a nominal timeout period of 1.6s. Over temperature, the actual timeout ranges from 1.12s (min) to 2.60s (max) across –40°C to +125°C. The timer resets on any edge (rising or falling) at the WDI pin and triggers RESET if no transition occurs within the timeout window.
What type of RESET output does the MAX6821LUK+ provide, and how does it interface to a microprocessor?
The MAX6821LUK+ provides an active-low push-pull RESET output. It drives low (≤0.4V) when asserted and high (≥0.8×VCC) when inactive - eliminating the need for an external pullup resistor. This output connects directly to standard µP reset inputs such as those on ARM Cortex-M or Renesas RL78 families.
Can the MAX6821LUK+ operate reliably at very low supply voltages?
Yes, the MAX6821LUK+ guarantees valid RESET assertion down to VCC = +1.0V, as specified in the Electrical Characteristics table. This ensures robust brownout protection even during deep battery discharge or unregulated power supply sag, making it suitable for portable equipment with aging primary cells.
Is manual reset functionality available on the MAX6821LUK+, and how is it implemented?
Yes, the MAX6821LUK+ includes an active-low manual reset input (MR) with internal 50kΩ pullup to VCC. Pulling MR low forces immediate RESET assertion, which persists for ≥140ms after MR returns high. A momentary switch from MR to GND implements field-service reset without external components or debounce circuitry.
MAX6821LUK+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.63V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
MAX6821LUK+ FAQ
1.How can I place an order for MAX6821LUK+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6821LUK+ 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 MAX6821LUK+ reliable?
The price and inventory of MAX6821LUK+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6821LUK+ is usually 5 days.
3.What payment methods are accepted for MAX6821LUK+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6821LUK+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6821LUK+?
MAX6821LUK+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6821LUK+ 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 MAX6821LUK+?
For technical support, including MAX6821LUK+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6821LUK+ requirements.
6.How does Aetrix verify that MAX6821LUK+ is sourced from the original manufacturer or authorized distributors?
All MAX6821LUK+ 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 MAX6821LUK+ meets industry standards.
7.What is the process for return or replacement of MAX6821LUK+?
All MAX6821LUK+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6821LUK+, 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 MAX6821LUK+ part is unused and in its original packaging.
Return procedure for MAX6821LUK+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX6821LUK+ Tags
-
MIC826SYMT-TR
Microchip Technology
-
APX803S-31SA-7
Diodes Incorporated
-
APX803L20-29SA-7
Diodes Incorporated
-
TPS3828-33DBVR
Texas Instruments
-
V6340RSP3B+
EM Microelectronic
-
EM6325CXSP5B-2.9+
EM Microelectronic
-
MCP120T-300I/TT
Microchip Technology
-
MCP130T-315I/TT
Microchip Technology
-
MCP120T-475I/TT
Microchip Technology
-
MCP111T-300E/TT
Microchip Technology
-
MCP120T-315I/TT
Microchip Technology
-
MCP809T-315I/TT
Microchip Technology
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
