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Analog Devices Inc./Maxim Integrated MAX818LEPA+
- Part No.:
- MAX818LEPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX818LEPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,731
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Product details
Overview
MAX818LEPA+ from Maxim Integrated is a +5V microprocessor supervisory circuit with active-low reset, battery backup switchover, watchdog timer (1.6s timeout), and on-board chip-enable gating. It features a 4.65V ±5% reset threshold, 200ms reset timeout, and 11µA quiescent current - designed for undervoltage monitoring and RAM protection in portable 5V systems.
For engineers reviewing the MAX818LEPA+ datasheet, MAX818LEPA+ pinout, MAX818LEPA+ application, or MAX818LEPA+ equivalent, this device delivers integrated power-fail immunity, battery freshness seal control, and CE signal gating without external logic - critical for reliable boot sequencing and data retention in embedded controllers and intelligent instruments.
Technical Context
The MAX818LEPA+ integrates a precision reset comparator with 4.65V threshold and 25mV hysteresis, a 1.6-second watchdog timer cleared by WDI edge transitions, and a bidirectional CMOS transmission gate for chip-enable signal control. Its battery switchover circuit uses internal P-channel MOSFETs to switch OUT between VCC and BATT based on voltage comparison and reset state.
It implements a battery freshness seal via PFO/CE OUT latching during power-cycle sequences, disables CE IN during reset assertion with 15µs hold time for write completion, and supports backup operation down to VBATT = 2.0V while drawing <1µA when VCC is fully absent.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±5% - ensures reliable µP reset initiation at nominal +5V supply brownout |
| Reset Timeout | 200ms - guarantees minimum reset pulse width for full µP initialization |
| Watchdog Timeout | 1.6s - provides fail-safe recovery window for firmware lockup detection |
| Quiescent Current | 11µA typical - enables multi-year battery life in always-on portable equipment |
| VCC to OUT RON | 5Ω max - minimizes voltage drop and power loss during main supply operation |
| BATT to OUT RON | 80Ω max - maintains sufficient drive strength for low-power RAM backup |
| CE Propagation Delay | 3ns typical - preserves timing integrity for high-speed memory access cycles |
Pinout & Package
MAX818LEPA+ is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), compatible with SO and DIP footprints. The package supports reflow soldering and offers thermal performance suitable for industrial temperature range operation (–40°C to +85°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Supply output for CMOS RAM | Switches automatically between VCC and BATT; connects to VCC via 5Ω PMOS when VCC > VRST |
| 2 VCC | +5V main supply input | Primary power source; powers internal circuitry and enables VCC-to-OUT path |
| 3 GND | Ground reference | 0V return for all analog and digital functions; must be low-impedance for noise immunity |
| 4 PFI | Power-fail comparator input | Unused in MAX818; connect to GND if not required - no internal function in this variant |
| 5 CE IN | Chip-enable input | Drives internal transmission gate; high-impedance when reset is asserted |
| 6 WDI | Watchdog input | Edge-sensitive; resets 1.6s timer on rising/falling transition; disabled if left floating |
| 7 RESET | Active-low reset output | Asserts low for ≥200ms after VCC rise above VRST or WDI timeout; sinks/sourcing capable |
| 8 BATT | Backup battery input | Supplies OUT when VCC < VRST and VCC < VBATT; supports voltages up to +6.0V |
Key Features
| Feature | Design Value |
|---|---|
| On-board CE gating | 3ns propagation delay and 40Ω series resistance enable direct interface with fast µP CE lines without timing degradation |
| Battery freshness seal | Latched via CE OUT state during power cycle - isolates BATT from leakage paths until first system power-up |
| Backup switchover hysteresis | 20mV - prevents oscillation during VCC/VBATT crossover and ensures clean mode transition |
| Reset threshold accuracy | ±5% over –40°C to +85°C - eliminates need for external trimming in cost-sensitive designs |
| Low-power watchdog | 11µA total supply current maintained even with watchdog enabled - no penalty for safety feature |
Applications
| Portable Data Loggers | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Battery-powered field instruments logging sensor data for weeks between charges. IC Role / Device Role / Timing Role: Supervises 5V rail, asserts RESET on brownout, gates CE to prevent RAM corruption during power collapse, and switches to BATT to retain volatile configuration. Use Value: Ensures zero data loss during unexpected power interruption and extends usable battery life via 11µA quiescent draw. |
Use Scenario: DIN-rail mounted controller modules operating in factory environments with noisy 24VDC supplies. IC Role / Device Role / Timing Role: Monitors local 5V LDO output, triggers watchdog reset on firmware hang, and isolates memory bus during undervoltage events using CE gating. Use Value: Prevents spurious writes to EEPROM or RAM during supply transients, improving system reliability without external supervision logic. |
| Medical Handheld Diagnostics | Smart Energy Meters |
|
Use Scenario: FDA-cleared handheld devices storing calibration history and patient session logs. IC Role / Device Role / Timing Role: Provides deterministic reset timing, enables battery freshness seal to guarantee shelf-life of sealed units, and backs up SRAM during battery swap. Use Value: Meets IEC 62304 safety requirements for reset assurance and eliminates risk of corrupted calibration data due to partial power loss. |
Use Scenario: ANSI C12.20-compliant meters with tamper-detection and time-of-use billing storage. IC Role / Device Role / Timing Role: Supervises 5V microcontroller supply, asserts RESET on AC dropout, and maintains RTC/SRAM power via BATT switchover during grid failure. Use Value: Guarantees accurate energy accumulation across blackouts with sub-200ms reset assertion and seamless backup transition. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX817LEPA+ | Lacks chip-enable gating and watchdog timer; retains PFI/PFO comparator and battery switchover | Suitable where CE control and watchdog are unnecessary - lower BOM cost and reduced pin count | Select when only basic reset + backup functionality is needed and µP handles CE timing internally |
| MAX819LEPA+ | Includes manual reset (MR) input and PFI/PFO comparator; omits CE gating and watchdog | Preferred for systems requiring operator-initiated reset or dual-supply monitoring (e.g., auxiliary rail fault detection) | Choose when field serviceability or secondary voltage supervision outweighs need for automatic CE control |
Compared with MAX817LEPA+ and MAX819LEPA+, the MAX818LEPA+ uniquely combines watchdog supervision and hardware CE gating - making it the only option among these three for applications demanding both autonomous firmware recovery and guaranteed memory bus isolation during brownout.
Availability
MAX818LEPA+ is available at Aetrix Electronics and suitable for portable data loggers, industrial PLC I/O modules, medical handheld diagnostics, and smart energy meters requiring stable component supply with long-term lifecycle support.
Supply support for MAX818LEPA+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.
The MAX817/MAX818/MAX819 product line was engineered specifically for robust, low-power supervisory functions in +5V microprocessor systems - emphasizing reset accuracy, battery backup integrity, and integration of critical system-level protection features.
FAQ
What is the reset threshold voltage of the MAX818LEPA+?
The MAX818LEPA+ has a factory-trimmed reset threshold of 4.65V ±5%, optimized for nominal +5V systems. This value is specified over the full industrial temperature range (–40°C to +85°C) and includes 25mV hysteresis to prevent chatter during slow VCC transitions. The "L" suffix in MAX818LEPA+ explicitly denotes the 4.65V version, distinguishing it from the 4.40V "M" variant.
Does the MAX818LEPA+ support manual reset functionality?
No, the MAX818LEPA+ does not include a manual reset (MR) input. That function is exclusive to the MAX819 family. The MAX818LEPA+ relies solely on power-on reset, watchdog timeout, and brownout detection for reset assertion. If manual reset capability is required, MAX819LEPA+ is the appropriate alternative within the same family.
How does the chip-enable gating work in the MAX818LEPA+?
The MAX818LEPA+ uses an internal CMOS transmission gate between CE IN and CE OUT. During normal operation (RESET high), CE IN passes directly to CE OUT with 3ns typical propagation delay and 40Ω series resistance. When RESET is asserted, the gate disables and CE IN goes high-impedance; CE OUT is pulled up to OUT. If CE IN is low at reset assertion, CE OUT remains low for 15µs to complete ongoing memory writes.
Can the MAX818LEPA+ monitor a secondary supply voltage like +3.3V?
The MAX818LEPA+ does not include a dedicated power-fail comparator input (PFI) - that feature is present only in MAX817 and MAX819. Therefore, it cannot directly monitor a secondary supply such as +3.3V. For dual-supply monitoring, MAX819LEPA+ should be selected, as it supports PFI input and allows PFO to trigger reset via MR connection.
What is the maximum allowable backup battery voltage for the MAX818LEPA+?
The MAX818LEPA+ supports a backup battery voltage (VBATT) from 2.0V to +6.0V, per Absolute Maximum Ratings. In normal operation, VBATT may exceed VCC - the internal switchover circuit safely connects BATT to OUT when VCC falls below both the reset threshold and VBATT. Operation is guaranteed down to VBATT = 2.0V with <1µA supply current in full battery-backup mode.
MAX818LEPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- -
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX818LEPA+ FAQ
1.How can I place an order for MAX818LEPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818LEPA+ 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 MAX818LEPA+ reliable?
The price and inventory of MAX818LEPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818LEPA+ is usually 5 days.
3.What payment methods are accepted for MAX818LEPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818LEPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818LEPA+?
MAX818LEPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818LEPA+ 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 MAX818LEPA+?
For technical support, including MAX818LEPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818LEPA+ requirements.
6.How does Aetrix verify that MAX818LEPA+ is sourced from the original manufacturer or authorized distributors?
All MAX818LEPA+ 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 MAX818LEPA+ meets industry standards.
7.What is the process for return or replacement of MAX818LEPA+?
All MAX818LEPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX818LEPA+, 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 MAX818LEPA+ part is unused and in its original packaging.
Return procedure for MAX818LEPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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