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Analog Devices Inc./Maxim Integrated MAX804SEPA+
- Part No.:
- MAX804SEPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX804SEPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:568
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Product details
Overview
MAX804SEPA+ from Maxim Integrated is a 3.3V/3.0V microprocessor supervisory circuit with active-high open-drain RESET output, 2.925V reset threshold (S-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover-designed for reliable power monitoring in embedded controllers and battery-powered systems.
For engineers reviewing the MAX804SEPA+ datasheet, MAX804SEPA+ pinout, MAX804SEPA+ application, or MAX804SEPA+ equivalent, this page delivers verified electrical parameters, package mapping to 8-pin SO (SOIC), functional role in brownout recovery and RAM backup, and validated alternative parts for 3V/3.3V µP supervision.
Technical Context
The MAX804SEPA+ integrates a precision reset comparator with ±2% threshold tolerance (2.925V rising/falling), a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path power switch: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω NMOS, enabling seamless switchover when VCC falls below 2.40V (VSW) while VBATT > VCC.
It features a dedicated PFI input (1.237V threshold, ±20mV hysteresis) for independent power-fail detection, an open-drain RESET output requiring external pull-up, and guaranteed RESET assertion down to VCC = 1.0V-ensuring robust operation during deep brownouts without battery support.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (±2%) - precisely targets 3.3V ±10% supplies; asserts reset before VCC drops below 2.85V. |
| Reset Timeout Period | 200ms (140–280ms over temp) - ensures µP completes power stabilization before release. |
| Watchdog Timeout | 1.6s (1.12–2.24s over temp) - detects µP lockup; cleared only by WDI edge or RESET assertion. |
| VCC Supply Current | 40µA (typ, VCC < 3.6V) - enables ultra-low-power operation in always-on battery-backed systems. |
| Battery Supply Current | 0.4–1µA (max) - minimizes drain on lithium coin cells during extended backup mode. |
| VBATT Switch Threshold | VSW = 2.40V (2.30–2.50V) - triggers switchover early enough to preserve CMOS RAM data (>2.0V). |
| PFO Input Threshold | 1.237V (±20mV hysteresis) - supports accurate external supply monitoring via resistor divider. |
Pinout & Package
MAX804SEPA+ is housed in an 8-pin SOIC (SO) package (package code S8+4), RoHS-compliant, with 1.27mm pitch and standard JEDEC MS-012 outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS); no external diode needed. |
| 2 - VCC | Main system supply input | Operates from 2.72V to 5.5V; powers internal circuitry and enables VOUT sourcing. |
| 3 - GND | Ground reference | Common return for all analog/digital functions; substrate tied to higher of VCC/VBATT. |
| 4 - PFI | Power-fail input | Monitors external supply via voltage divider; trips PFO low at 1.237V with 20mV hysteresis. |
| 5 - PFO | Power-fail output | Active-low open-drain signal; can be wired to MR on compatible supervisors for cascaded reset. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets watchdog timer; cannot be disabled. |
| 7 - RESET | Active-high open-drain reset output | Requires external pull-up to VCC; asserts high during reset; inverse of MAX690-style RESET. |
| 8 - VBATT | Backup battery input | Accepts up to 6.0V; may exceed VCC; connects to VOUT when VCC < VSW or < 1.75V. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during severe brownouts where VCC collapses below 1.5V. |
| Battery-backup switchover with 2.40V threshold | Triggers before VOUT drops below 2.0V, preserving static RAM data integrity without external logic. |
| ±2% reset threshold accuracy | Tighter than MAX690/MAX704 (±4%), enabling precise compatibility with 3.3V ±10% systems. |
| 1.6s watchdog timer with edge-clearing | Eliminates need for software timer management; immune to stuck WDI states via transition detection. |
| 40µA VCC supply current (typ) | Reduces standby power in portable equipment; allows multi-year operation on coin-cell batteries. |
Applications
| Battery-Powered Embedded Controllers | Intelligent Portable Instruments |
|---|---|
Use Scenario: Industrial handheld meter with lithium coin-cell backup and ARM Cortex-M0 MCU. IC Role / Device Role / Timing Role: Supervises 3.3V rail, asserts RESET on brownout, switches RAM to VBATT at 2.40V, and monitors battery health via PFI. Use Value: Prevents firmware corruption during field battery swaps and extends operational uptime beyond main supply failure. |
Use Scenario: Handheld gas analyzer with real-time sensor processing and nonvolatile RAM retention. IC Role / Device Role / Timing Role: Provides 200ms power-on reset delay, 1.6s watchdog supervision, and seamless VBATT switchover to preserve calibration data. Use Value: Eliminates need for external reset sequencer or discrete power-switching MOSFETs. |
| Critical µP Power Monitoring | Portable Medical Devices |
Use Scenario: Remote telemetry node powered by rechargeable Li-ion with intermittent solar charging. IC Role / Device Role / Timing Role: Monitors VCC for undervoltage, triggers watchdog if MCU hangs, and asserts RESET before VCC drops below 2.85V. Use Value: Meets IEC 62304 Class B SW safety requirements for autonomous reset recovery. |
Use Scenario: Wearable ECG monitor with flash memory and SRAM buffer backed by CR2032. IC Role / Device Role / Timing Role: Supplies clean 3.3V to RAM during main supply interruption; uses PFO to flag low-battery condition to host MCU. Use Value: Guarantees patient data persistence across 100+ power cycles without capacitor-based hold-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX804TEPA+ | Reset threshold = 3.075V (±2%), otherwise identical pinout, timing, and features. | Suitable for 3.3V ±5% systems; asserts reset later than MAX804SEPA+, delaying response to marginal supplies. | Select when system VCC regulation tightness requires higher trip point to avoid nuisance resets. |
| MAX804REPA+ | Reset threshold = 2.625V (±2%), same SO-8 package and functional set. | Optimized for 3.0V ±10% rails; asserts reset earlier, allowing longer backup window before RAM data loss. | Choose for designs using 3.0V LDOs with wider tolerance or where extended battery runtime is critical. |
Compared with MAX804TEPA+ and MAX804REPA+, the MAX804SEPA+ provides optimal balance for 3.3V ±10% systems-asserting reset at 2.925V to prevent premature shutdown while ensuring sufficient margin above CMOS RAM minimum operating voltage (2.0V).
Availability
MAX804SEPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply across industrial temperature range (-40°C to +85°C).
Supply support for MAX804SEPA+ 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 and mixed-signal ICs for power management, sensing, and interface applications in industrial, medical, and communications systems.
The MAX804SEPA+ belongs to the MAX80x family of µP supervisory circuits engineered specifically for robust 3.0V/3.3V system power monitoring, battery backup, and watchdog functionality in space-constrained embedded platforms.
FAQ
What is the reset threshold voltage of the MAX804SEPA+?
The MAX804SEPA+ has a nominal reset threshold voltage of 2.925V, with ±2% tolerance over temperature and supply voltage. This value applies to both rising and falling VCC transitions and is optimized for 3.3V ±10% power systems. The device guarantees reset assertion before VCC falls below 2.85V and prevents false triggering above 3.00V under normal operation.
Does the MAX804SEPA+ support battery backup with lithium cells?
Yes, the MAX804SEPA+ fully supports lithium coin-cell backup (e.g., CR2032, 3.0V nominal) via its VBATT pin. It allows VBATT to exceed VCC, automatically switching VOUT from VCC to VBATT when VCC falls below 2.40V (VSW). Battery supply current is limited to ≤1µA, enabling multi-year backup life. The internal 140Ω switch ensures low-loss connection to RAM during switchover.
How does the watchdog timer function on the MAX804SEPA+?
The MAX804SEPA+ watchdog timer has a fixed 1.6s timeout (1.12–2.24s over temperature) and is cleared only by a rising or falling edge on the WDI pin-or by an active RESET condition. Unlike older families, the watchdog cannot be disabled. If WDI remains static (high or low) for >1.6s, RESET is asserted for 200ms. This ensures deterministic recovery from firmware hangs without software intervention.
What is the purpose of the PFI and PFO pins on the MAX804SEPA+?
The PFI (Power-Fail Input) pin accepts an external voltage divider to monitor auxiliary supplies, comparing it to a precise 1.237V internal reference. When PFI falls below this threshold, the open-drain PFO (Power-Fail Output) pulls low. PFO can trigger interrupts or be connected to MR on compatible supervisors (e.g., MAX704) to initiate system reset-enabling flexible, multi-rail fault detection without additional ICs.
Is the MAX804SEPA+ pin-compatible with other MAX80x variants?
Yes, all MAX80x variants-including MAX804TEPA+, MAX804REPA+, MAX804SEPA+, and MAX805x series-are fully pin-compatible in the 8-pin SOIC (S8+4) and PDIP packages. They share identical pinout, timing, and functional architecture; only reset threshold (T/S/R suffix), RESET polarity (MAX804 vs. MAX805), and power-fail tolerance differ. No PCB changes are required when substituting within the same package type.
MAX804SEPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.925V
- Output:
- Open Drain, Open Drain
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX804SEPA+ FAQ
1.How can I place an order for MAX804SEPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX804SEPA+ 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 MAX804SEPA+ reliable?
The price and inventory of MAX804SEPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX804SEPA+ is usually 5 days.
3.What payment methods are accepted for MAX804SEPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX804SEPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX804SEPA+?
MAX804SEPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX804SEPA+ 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 MAX804SEPA+?
For technical support, including MAX804SEPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX804SEPA+ requirements.
6.How does Aetrix verify that MAX804SEPA+ is sourced from the original manufacturer or authorized distributors?
All MAX804SEPA+ 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 MAX804SEPA+ meets industry standards.
7.What is the process for return or replacement of MAX804SEPA+?
All MAX804SEPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX804SEPA+, 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 MAX804SEPA+ part is unused and in its original packaging.
Return procedure for MAX804SEPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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