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Analog Devices Inc./Maxim Integrated MAX818LESA+
- Part No.:
- MAX818LESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX818LESA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,443
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Product details
Overview
MAX818LESA+ 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 embedded systems.
For engineers reviewing the MAX818LESA+ datasheet, MAX818LESA+ pinout, MAX818LESA+ application, or MAX818LESA+ equivalent, this device delivers integrated power-fail detection, manual-reset-free supervision, and CE signal gating - critical for battery-backed microcontroller systems requiring deterministic reset behavior and data integrity during brownouts.
Technical Context
The MAX818LESA+ implements a precision bandgap-based reset comparator with 25mV hysteresis and a dedicated watchdog timer that clears on rising/falling edges at WDI. Its internal P-channel MOSFET switch enables seamless VCC-to-BATT switchover when VCC falls below both VRST (4.65V) and VBATT, with 80Ω BATT-to-OUT on-resistance.
It integrates a 3ns chip-enable transmission gate (CE IN → CE OUT) controlled by RESET state, ensuring CMOS RAM write-cycle completion during power-down. The CE path remains disabled for 15µs after reset assertion, with propagation delay tested at 3–8ns under 50Ω/50pF conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±5% - ensures reliable reset assertion before +5V supply drops below µP operational minimum. |
| Reset Timeout | 200ms - guarantees sufficient hold time for processor initialization after power-up or brownout recovery. |
| Watchdog Timeout | 1.6s - provides fail-safe reset if µP fails to toggle WDI, supporting real-time task supervision. |
| Quiescent Current | 11µA - enables multi-year battery life in always-on portable instrumentation and memory backup circuits. |
| BATT-to-OUT RON | 80Ω - limits voltage drop during battery-backup mode, preserving >2.7V at OUT for 3V CMOS RAM. |
| CE Propagation Delay | 3–8ns - supports high-speed µP bus timing without violating setup/hold requirements for CE-driven peripherals. |
| Supply Range | +4.75V to +5.5V - matches standard +5V regulator tolerance and accommodates line/load regulation drift. |
Pinout & Package
MAX818LESA+ is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), thermally enhanced for portable applications and compatible with SO-8 and DIP-8 footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Supply output | Switches between VCC and BATT; powers CMOS RAM during brownout with <80Ω on-resistance. |
| 2 VCC | Main supply input | +5V system rail; powers internal circuitry and enables VCC-to-OUT path above reset threshold. |
| 3 GND | Ground reference | 0V return for all analog/digital functions; must be low-impedance for reset accuracy. |
| 4 PFI | Power-fail comparator input | Unused on MAX818; connect to GND. Not functional - MAX818 lacks PFI/PFO circuitry. |
| 5 CE IN | Chip-enable input | Drives CE transmission gate; high-impedance when RESET asserted to prevent spurious writes. |
| 6 WDI | Watchdog input | Edge-sensitive; resets 1.6s timer on rising/falling transitions; disabled if left floating or high-Z. |
| 7 RESET | Active-low reset output | Open-drain, sinks 3.2mA; holds µP in reset for 200ms after VCC rises above 4.65V. |
| 8 BATT | Battery backup input | Accepts 2.0V–5.5V; powers OUT and internal logic when VCC < VRST and VCC < VBATT. |
Key Features
| Feature | Design Value |
|---|---|
| On-board CE gating | 3ns propagation delay with 15µs hold time during reset - prevents RAM corruption during power collapse. |
| Battery freshness seal | Enables OEM battery shelf-life preservation by disconnecting BATT until first power-up sequence completes. |
| Fast transient immunity | Ignores VCC spikes <100µs duration - avoids false resets from switching noise or ESD-induced supply glitches. |
| Backup switchover hysteresis | 20mV - prevents oscillation during VCC/VBATT crossover and ensures clean transition into/out of battery mode. |
| Low-power watchdog | 1.6s timeout with edge-triggered clear - consumes <150µA even when externally driven high, minimizing standby drain. |
Applications
| Portable Data Loggers | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Battery-powered field instruments recording sensor data over weeks without AC power. IC Role / Device Role / Timing Role: Supervises +5V rail, asserts RESET during brownout, gates CE to freeze RAM writes, and switches to backup battery to retain last valid measurement. Use Value: Ensures nonvolatile data retention with <1µA battery leakage in backup mode and deterministic 200ms reset hold for safe µP restart. |
Use Scenario: DIN-rail mounted controllers operating in factory environments with unstable 24VDC-to-5V conversion. IC Role / Device Role / Timing Role: Monitors 5V supply integrity, triggers watchdog reset on firmware lockup, and isolates RAM CE during undervoltage events. Use Value: Prevents corrupted I/O register states via sub-8ns CE gating and eliminates need for external reset supervisor ICs. |
| Medical Point-of-Care Devices | Smart Meters with Tamper Detection |
|
Use Scenario: Handheld diagnostic tools requiring FDA-compliant power sequencing and data integrity. IC Role / Device Role / Timing Role: Provides certified reset timing (200ms min), battery-freshness seal activation during manufacturing, and failsafe watchdog supervision. Use Value: Meets IEC 62304 software safety requirements by guaranteeing deterministic reset behavior and eliminating manual reset hardware. |
Use Scenario: Electricity meters storing tariff data and tamper logs in battery-backed SRAM across 10+ year deployments. IC Role / Device Role / Timing Role: Switches SRAM supply to coin cell during mains failure, gates CE to block write cycles during brownout, and monitors supply stability. Use Value: Achieves >10-year backup runtime using <11µA quiescent current and 80Ω BATT-to-OUT switch resistance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX817LESA+ | Lacks chip-enable gating and watchdog timer; retains PFI/PFO power-fail comparator. | Suitable where CE control and watchdog are unnecessary but power-fail warning is required. | Select MAX817LESA+ only if PFI-based low-voltage warning is needed and CE gating is omitted from design. |
| MAX819LESA+ | Includes manual reset (MR) input and PFI/PFO comparator; omits CE gating and watchdog. | Required when operator-initiated reset or external supply monitoring (e.g., auxiliary rails) is mandatory. | Choose MAX819LESA+ when field-service reset capability or multi-rail supervision justifies added pin count and complexity. |
Compared with MAX817LESA+ and MAX819LESA+, the MAX818LESA+ uniquely combines watchdog supervision and CE signal gating in a single 8-pin µMAX package - eliminating two discrete functions while maintaining identical 4.65V reset threshold and 11µA supply current.
Availability
MAX818LESA+ is available at Aetrix Electronics and suitable for portable instrumentation, industrial PLC modules, medical diagnostics equipment, and smart metering systems requiring stable component supply and long-term lifecycle support.
Supply support for MAX818LESA+ 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, sensing, and interface applications in industrial, automotive, and computing markets.
The MAX817/MAX818/MAX819 family was engineered specifically for +5V microprocessor systems needing integrated reset, battery switchover, and peripheral signal control - reducing BOM count and PCB area in space-constrained embedded designs.
FAQ
What is the reset threshold voltage of the MAX818LESA+?
The MAX818LESA+ has a factory-trimmed reset threshold of 4.65V ±5%, optimized for +5V systems. This value is guaranteed over temperature (0°C to +70°C) and ensures reset assertion before most 5V microprocessors fall out of specification. The 'L' suffix explicitly denotes the 4.65V version, distinguishing it from the 4.40V 'M' variant. The threshold exhibits only ±3mV drift from -40°C to +85°C per characterization data.
Does the MAX818LESA+ include a manual reset input?
No, the MAX818LESA+ does not feature a manual reset (MR) input. That function is exclusive to the MAX819 series. The MAX818LESA+ relies solely on power-supply monitoring and watchdog timeout for reset generation. If manual reset capability is required, the MAX819LESA+ is the direct alternative within the same family, though it omits both the watchdog timer and chip-enable gating found in the MAX818LESA+.
How does the chip-enable gating function work in the MAX818LESA+?
The MAX818LESA+ integrates a bidirectional transmission gate between CE IN (pin 5) and CE OUT (pin ? - note: pin numbering confirms CE OUT is pin 5 in MAX818 functional diagram). When RESET is deasserted, CE IN passes directly to CE OUT with 3–8ns propagation delay. When RESET asserts, the gate disables within 15µs, forcing CE OUT high-impedance to prevent spurious writes to CMOS RAM during power collapse. This function is absent in MAX817/MAX819 variants.
Can the MAX818LESA+ monitor a secondary power supply like a 3.3V rail?
No, the MAX818LESA+ lacks a dedicated power-fail comparator input (PFI) and output (PFO); those features are present only in MAX817 and MAX819. Therefore, it cannot generate power-fail warnings for auxiliary supplies. For dual-rail monitoring, use MAX819LESA+ with its PFI input, or pair MAX818LESA+ with an external comparator. The MAX818LESA+ focuses exclusively on supervising the primary +5V VCC rail and managing battery backup.
What is the maximum battery voltage supported by the MAX818LESA+?
The MAX818LESA+ supports battery voltages from 2.0V to 5.5V on the BATT pin, as specified in Absolute Maximum Ratings and Electrical Characteristics. During battery-backup mode (VCC < VRST and VCC < VBATT), the device draws <1µA from the battery when VCC is >1V below VBATT. The internal 80Ω P-channel MOSFET switch ensures minimal dropout, enabling reliable operation of 3V CMOS RAM even with aging alkaline or lithium coin cells.
MAX818LESA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX818LESA+ FAQ
1.How can I place an order for MAX818LESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818LESA+ 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 MAX818LESA+ reliable?
The price and inventory of MAX818LESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818LESA+ is usually 5 days.
3.What payment methods are accepted for MAX818LESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818LESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818LESA+?
MAX818LESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818LESA+ 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 MAX818LESA+?
For technical support, including MAX818LESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818LESA+ requirements.
6.How does Aetrix verify that MAX818LESA+ is sourced from the original manufacturer or authorized distributors?
All MAX818LESA+ 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 MAX818LESA+ meets industry standards.
7.What is the process for return or replacement of MAX818LESA+?
All MAX818LESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX818LESA+, 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 MAX818LESA+ part is unused and in its original packaging.
Return procedure for MAX818LESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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