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Analog Devices Inc./Maxim Integrated MAX805LEPA+
- Part No.:
- MAX805LEPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX805LEPA+.pdf
- Description:
- IC SUPERVISOR MPU 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,035
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Product details
Overview
The MAX805LEPA+ from Maxim Integrated is a microprocessor supervisory circuit providing active-high reset output, battery-backup switchover, watchdog timer, and power-fail detection for +5V systems. It asserts RESET when VCC drops below 4.65V, delivers 200ms reset pulse width, consumes 200–500µA supply current, and supports backup-battery switching with 40mV hysteresis. It is used in industrial controllers and battery-powered instrumentation requiring reliable power monitoring.
For engineers reviewing the MAX805LEPA+ datasheet, MAX805LEPA+ pinout, MAX805LEPA+ application, or MAX805LEPA+ equivalent, key selection criteria include its active-high reset logic (vs. active-low alternatives), guaranteed RESET assertion down to VCC = 1.2V, ±2% power-fail accuracy, 1.6s watchdog timeout, and compatibility with lithium backup batteries up to 4.80V.
Technical Context
The MAX805LEPA+ integrates four core functions in a single 8-pin SOIC package: a precision 4.65V reset threshold detector with 40mV hysteresis, a 1.6s watchdog timer cleared by WDI edges or reset assertion, a 1.25V reference-based power-fail comparator (PFI/PFO), and a bidirectional battery switchover circuit that connects VBATT to VOUT only when VCC falls below the reset threshold and VBATT exceeds VCC by ≥20mV.
Its active-high RESET output is electrically distinct from the MAX690A/MAX802L family's active-low RESET: MAX805LEPA+ drives RESET high during normal operation and pulls it low only during reset events, enabling direct interface with µPs like the Intel 80C51 requiring active-high reset signaling. The internal PMOS switch for VOUT exhibits 5Ω on-resistance when VCC is valid and 80Ω when operating from VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - triggers reset when VCC falls below this level; guarantees system restart before +5V rail collapse. |
| Reset Pulse Width | 200ms typical - ensures µP reset duration meets minimum timing requirements for reliable initialization. |
| Watchdog Timeout | 1.6s - provides fault-detection window for software hangs; cleared by WDI edge transitions. |
| Supply Current | 200–500µA - enables long-term operation in battery-backed systems without excessive drain. |
| Battery-Backup Current | ≤5.0µA over full temperature range - minimizes self-discharge when VCC = 0V and VBATT = 2.8V. |
| Power-Fail Accuracy | ±2% - ensures precise early warning of supply degradation for controlled shutdown sequences. |
| RESET Assertion Voltage | Valid down to VCC = 1.2V - maintains functional reset capability during deep brownout conditions. |
Pinout & Package
MAX805LEPA+ is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body and through-hole mounting. Pin 1 is marked with a notch or dot; pin numbering follows standard counter-clockwise orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | CMOS RAM supply output | Switches between VCC and VBATT based on voltage comparison; 5Ω/80Ω PMOS path ensures low-dropout backup power delivery. |
| VCC (Pin 2) | +5V main supply input | Primary power source; powers internal circuitry and defines reset threshold reference point. |
| GND (Pin 3) | Ground reference | Common return path for all analog and digital functions; substrate connection must remain unconnected. |
| PFI (Pin 4) | Power-fail comparator input | Monitors external voltage divider; asserts PFO low when input falls below 1.25V reference. |
| PFO (Pin 5) | Power-fail output | Open-drain output signaling supply degradation; requires external pull-up for µP interrupt generation. |
| WDI (Pin 6) | Watchdog input | Edge-sensitive control pin; floating or high-impedance state disables watchdog; 50ns minimum pulse width detectable. |
| RESET (Pin 7) | Active-high reset output | Push-pull output driven high during normal operation; pulled low for 200ms during reset events. |
| VBATT (Pin 8) | Backup battery input | Accepts 2.8–4.80V lithium cells; internal comparator enables switchover only when VBATT > VCC + 20mV. |
Key Features
| Feature | Design Value |
|---|---|
| Active-high RESET output | Directly interfaces with µPs requiring high-asserted reset (e.g., Intel 80C51), eliminating external inverters. |
| Guaranteed RESET at VCC = 1.2V | Ensures fail-safe reset assertion even during severe brownout, supporting robust system recovery. |
| 40mV switchover hysteresis | Prevents oscillatory VOUT switching during slow VCC decay, protecting RAM data integrity. |
| 1.25V precision internal reference | Enables accurate PFI monitoring across temperature; ±2% power-fail accuracy specified for critical shutdown decisions. |
| 50nA PFI input leakage | Minimizes error in external voltage dividers, allowing high-impedance sensing networks without calibration drift. |
Applications
| Battery-Powered Computers and Controllers | Intelligent Instruments |
|---|---|
Use Scenario: Portable data loggers powered by coin-cell batteries require nonvolatile memory retention during AC power loss. IC Role / Device Role / Timing Role: MAX805LEPA+ monitors VCC, switches VOUT to VBATT upon brownout, and asserts RESET to halt µP execution while preserving RAM contents. Use Value: Enables 10+ year battery life in backup mode (≤5µA quiescent current) and eliminates need for external switchover MOSFETs or discrete reset generators. | Use Scenario: Handheld multimeters with real-time clock and configuration storage must survive brief power interruptions. IC Role / Device Role / Timing Role: MAX805LEPA+ provides 200ms active-high RESET pulse synchronized to VCC recovery and detects impending supply failure via PFI to trigger EEPROM save routines. Use Value: Guarantees deterministic µP restart timing and prevents corrupted calibration data by initiating save operations ≥10ms before PFO asserts. |
| Critical μP Power Monitoring | Industrial PLC I/O Modules |
Use Scenario: Programmable logic controllers in factory automation rely on uninterrupted µP operation during line transients. IC Role / Device Role / Timing Role: MAX805LEPA+ continuously monitors +5V rail, triggers watchdog reset if firmware stalls, and asserts RESET within 2µs of VCC crossing 4.65V threshold. Use Value: Reduces mean time to failure by detecting both hardware faults (brownout) and software faults (watchdog timeout) with independent timing paths. | Use Scenario: Distributed I/O modules powered from centralized 24V DC supplies with local +5V regulation require brownout immunity. IC Role / Device Role / Timing Role: MAX805LEPA+ senses regulated +5V output, disables peripheral drivers via RESET before rail collapse, and uses PFO to signal host controller of imminent power loss. Use Value: Prevents bus contention and latch-up by coordinating graceful shutdown across multiple modules using synchronized PFO interrupts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX805LCSA | Same functionality and pinout, but rated for 0°C to +70°C industrial temperature range instead of -40°C to +85°C. | Suitable for commercial-grade embedded systems without extended thermal requirements. | Select MAX805LCSA for cost-sensitive designs operating within ambient temperatures not exceeding +70°C. |
| MAX813LEPA+ | Provides identical 4.65V reset threshold and 200ms pulse width, but features active-low RESET and lacks PFI/PFO power-fail comparator. | Applicable where only basic reset supervision is needed and power-fail warning is handled externally. | Choose MAX813LEPA+ when power-fail detection is unnecessary and board space allows for external comparator circuitry. |
Compared with MAX805LCSA and MAX813LEPA+, the MAX805LEPA+ uniquely combines extended temperature operation (-40°C to +85°C), active-high reset logic, and integrated power-fail warning in a single 8-pin DIP-enabling simplified BOMs and reduced PCB area in ruggedized industrial designs.
Availability
MAX805LEPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical μP power monitoring applications requiring stable component supply across extended temperature ranges.
Supply support for MAX805LEPA+ 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 is a semiconductor company specializing in analog and mixed-signal ICs for power management, interface, sensing, and reliability-critical applications.
The MAX805L series belongs to Maxim's microprocessor supervisory product line, designed specifically to replace discrete reset generators and battery switchover circuits in embedded systems requiring high-accuracy voltage monitoring and fail-safe reset behavior.
FAQ
What is the reset threshold voltage for the MAX805LEPA+?
The MAX805LEPA+ has a nominal reset threshold voltage of 4.65V, with a guaranteed tolerance of ±150mV over the full -40°C to +85°C operating temperature range. This threshold is referenced internally to a precision bandgap, ensuring consistent brownout detection across voltage and temperature variations. The MAX805LEPA+ asserts its active-high RESET output low when VCC falls below this level and holds it low for 200ms after VCC rises above the threshold.
Does the MAX805LEPA+ support battery backup switching?
Yes, the MAX805LEPA+ supports automatic battery backup switching via its VBATT and VOUT pins. When VCC drops below the 4.65V reset threshold and VBATT exceeds VCC by at least 20mV, the device connects VBATT to VOUT through an 80Ω PMOS switch. The 40mV hysteresis prevents chattering during slow VCC decay. In backup mode, quiescent current is ≤5.0µA over temperature, making the MAX805LEPA+ suitable for multi-year lithium battery operation.
How does the watchdog timer function in the MAX805LEPA+?
The MAX805LEPA+ incorporates a 1.6s watchdog timer monitored via the WDI pin. If WDI remains static (high or low) for longer than 1.6s, the timer expires and triggers a 200ms RESET pulse. The timer clears on any rising or falling edge at WDI, on RESET assertion, or when WDI is three-stated. The MAX805LEPA+ guarantees detection of pulses as short as 50ns, enabling robust firmware health monitoring without requiring precise timing margins.
What is the purpose of the PFI and PFO pins on the MAX805LEPA+?
The PFI (Power-Fail Input) and PFO (Power-Fail Output) pins on the MAX805LEPA+ implement a dedicated undervoltage detection channel independent of the main reset function. PFI compares an external voltage (typically from a resistor divider on the unregulated supply) against an internal 1.25V reference; when PFI falls below 1.25V, PFO goes low to signal impending power loss. This allows µPs to execute controlled shutdown sequences before VCC crosses the 4.65V reset threshold, and the MAX805LEPA+ guarantees ±2% accuracy for this comparator.
Can the MAX805LEPA+ operate with a 3.3V supply?
No, the MAX805LEPA+ is specified only for +5V systems: its reset threshold is fixed at 4.65V, and its electrical characteristics (including RESET output drive strength and VOUT switching) are characterized for VCC = 4.75V to 5.5V. Attempting to operate the MAX805LEPA+ from 3.3V will result in failure to assert RESET, incorrect PFI comparison, and undefined VOUT behavior. For 3.3V applications, consider the MAX6326 or MAX6369 families, which offer compatible functionality with lower-voltage thresholds.
MAX805LEPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX805LEPA+ FAQ
1.How can I place an order for MAX805LEPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805LEPA+ 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 MAX805LEPA+ reliable?
The price and inventory of MAX805LEPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805LEPA+ is usually 5 days.
3.What payment methods are accepted for MAX805LEPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805LEPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805LEPA+?
MAX805LEPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805LEPA+ 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 MAX805LEPA+?
For technical support, including MAX805LEPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805LEPA+ requirements.
6.How does Aetrix verify that MAX805LEPA+ is sourced from the original manufacturer or authorized distributors?
All MAX805LEPA+ 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 MAX805LEPA+ meets industry standards.
7.What is the process for return or replacement of MAX805LEPA+?
All MAX805LEPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX805LEPA+, 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 MAX805LEPA+ part is unused and in its original packaging.
Return procedure for MAX805LEPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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