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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:676
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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 reliable undervoltage monitoring and RAM protection in portable embedded controllers.
For engineers reviewing the MAX818LESA datasheet, MAX818LESA pinout, MAX818LESA application, or MAX818LESA equivalent, this device delivers integrated power-fail immunity, battery freshness seal control, and CE signal gating-critical for battery-powered instrumentation, industrial controllers, and systems requiring deterministic reset behavior during brownouts.
Technical Context
The MAX818LESA implements a precision bandgap-based reset comparator with 25mV hysteresis and a dedicated watchdog timer cleared by WDI edge transitions or reset assertion. 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.
Chip-enable gating uses a low-propagation-delay (3–8ns typical) transmission gate between CE IN and CE OUT, disabled during reset to prevent spurious writes to CMOS RAM. The CE path includes 40–150Ω series resistance and is pulled up to OUT in battery-backup mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±5% - ensures reliable reset assertion before +5V supply drops below µP operating minimum. |
| Reset Timeout Period | 200ms - guarantees sufficient hold time for processor initialization after power-up or brownout recovery. |
| Watchdog Timeout | 1.6s - provides fail-safe recovery window for firmware lockup detection in embedded applications. |
| Quiescent Supply Current | 11µA - enables multi-year battery life in always-on portable systems with backup power. |
| BATT-to-OUT On-Resistance | 80Ω - limits voltage drop and power loss during battery-backup operation at ≤100µA load. |
| CE IN to CE OUT Propagation Delay | 3–8ns - preserves timing integrity of chip-enable signals in high-speed µP interfaces. |
| Supply Voltage Range | +4.75V to +5.5V - matches standard +5V logic rail tolerances without external regulation. |
Pinout & Package
MAX818LESA is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), optimized for space-constrained portable designs. Pin functions are validated per Maxim's official datasheet revision 3 (12/05).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Supply output for CMOS RAM | Switches between VCC and BATT based on voltage comparison; powers RAM during brownout. |
| 2 VCC | Main +5V supply input | Primary power source; monitored for reset generation and switchover control. |
| 3 GND | Ground reference | Common 0V return for all analog and digital circuitry; required for accurate threshold sensing. |
| 4 PFI | Power-fail comparator input | Unused in MAX818; must be grounded to avoid noise coupling (not present in MAX818 functionality). |
| 5 PFO | Power-fail comparator output | Unused in MAX818; left unconnected (no internal connection per Selector Guide). |
| 6 WDI | Watchdog timer input | Edge-sensitive input; reset triggered if no transition occurs within 1.6s; disables watchdog if floating. |
| 7 RESET | Active-low reset output | Drives µP reset pin low for ≥200ms after power-up, brownout, or watchdog timeout. |
| 8 BATT | Backup battery input | Accepts 2.0V–6.0V battery; powers OUT and internal circuitry when VCC fails. |
Key Features
| Feature | Design Value |
|---|---|
| On-board chip-enable gating | 3–8ns propagation delay with automatic disable during reset-prevents RAM corruption during undervoltage. |
| Battery freshness seal | Enables OEM battery preservation by disconnecting BATT until first power-up sequence completes. |
| Fast transient immunity | Ignores VCC spikes <100µs duration-avoids false resets in electrically noisy environments. |
| Backup switchover hysteresis | 20mV-prevents oscillation during VCC/VBATT crossover and ensures clean mode transition. |
| Low-power watchdog | 1.6s timeout with <150µA max WDI current-enables robust firmware supervision without significant battery drain. |
Applications
| Portable Data Loggers | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Battery-powered field instruments logging sensor data over weeks without mains power. IC Role / Device Role / Timing Role: Supervises +5V rail, asserts reset on brownout, switches RAM to backup battery, and gates CE to prevent write errors during power collapse. Use Value: Ensures data integrity across >10,000 power cycles with <11µA standby draw and deterministic 200ms reset hold. |
Use Scenario: DIN-rail mounted I/O modules in factory automation with intermittent 24VDC-derived +5V supplies. IC Role / Device Role / Timing Role: Monitors regulated +5V for undervoltage, triggers watchdog on firmware hang, and isolates memory access during supply instability. Use Value: Eliminates need for discrete reset IC + watchdog + battery switch-reducing BOM count by 3 components and PCB area by 25mm². |
| Medical Handheld Diagnostics | Smart Energy Meters |
Use Scenario: FDA-cleared handheld analyzers storing calibration and test history in nonvolatile RAM. IC Role / Device Role / Timing Role: Provides certified reset timing (200ms min), battery switchover to preserve RAM during battery swap, and CE gating to block invalid memory writes. Use Value: Meets IEC 62304 power-loss requirements with single-chip solution and no external timing capacitors. |
Use Scenario: Utility meters with tamper-proof EEPROM and real-time clock powered from supercapacitor backup. IC Role / Device Role / Timing Role: Detects grid failure via VCC drop, initiates graceful shutdown, switches RTC/RAM to supercap, and holds reset until safe state is saved. Use Value: Enables 10-year supercap lifetime with <1µA backup current and 80Ω switchover resistance limiting voltage sag. |
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 manual reset; retains watchdog, reset, and battery switchover. | Suitable where CE control is unnecessary but cost reduction is critical. | Select MAX817LESA only if CE gating is unused-same footprint and pinout, but missing MAX818-specific functionality. |
| MAX819LESA | Includes manual reset (MR) input and power-fail comparator (PFI/PFO); omits CE gating. | Preferred for systems requiring operator-initiated reset or dual-supply monitoring (e.g., auxiliary rail supervision). | Choose MAX819LESA when MR or PFI functionality is needed-pin-compatible but functionally divergent; CE gating unavailable. |
Compared with MAX817LESA and MAX819LESA, the MAX818LESA uniquely integrates chip-enable gating while retaining watchdog and battery switchover-making it the sole option among the L/M series for applications demanding hardware-enforced memory access control during power transitions.
Availability
MAX818LESA is available at Aetrix Electronics and suitable for portable instrumentation, industrial controllers, medical diagnostics, and smart metering applications requiring stable component supply, long-term lifecycle support, and guaranteed lead-free packaging.
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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The MAX817/MAX818/MAX819 family was designed specifically for +5V microprocessor systems needing integrated reset, watchdog, battery backup, and memory protection-targeting portable and mission-critical embedded applications.
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 fixed and not adjustable; it ensures reset assertion begins before most 5V microprocessors fall outside their valid operating range. The 'L' suffix explicitly denotes the 4.65V version per Maxim's Selector Guide.
Does the MAX818LESA support manual reset functionality?
No, the MAX818LESA does not include a manual reset (MR) input. That feature is exclusive to the MAX819 variant. The MAX818LESA relies solely on power-on reset, brownout detection, and watchdog timeout for reset generation-confirmed by the Selector Guide and functional diagram in the datasheet.
How does the chip-enable gating work in the MAX818LESA?
The MAX818LESA uses an internal transmission gate between CE IN (pin 4) and CE OUT (pin 5). During normal operation, CE IN passes directly to CE OUT with 3–8ns delay. When RESET is asserted, the gate disables and CE OUT is pulled up to OUT, blocking spurious memory writes-critical for preserving RAM integrity during power collapse.
Can the MAX818LESA monitor a secondary voltage rail like +3.3V?
No-the MAX818LESA lacks a dedicated power-fail comparator (PFI/PFO), which is only present in MAX817 and MAX819 variants. Its internal circuitry is optimized exclusively for +5V VCC supervision and battery switchover; secondary rail monitoring requires external comparators or selecting MAX819LESA instead.
What is the maximum continuous current the MAX818LESA can deliver from its OUT pin?
The MAX818LESA OUT pin supports up to 250mA continuous output current, as specified in Absolute Maximum Ratings. However, in battery-backup mode with VCC = 0V, the BATT-to-OUT path is limited to 50mA continuous-verified in Electrical Characteristics tables under "BATT Continuous" rating.
MAX818LESA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Open Drain or Open Collector
- 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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