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Analog Devices Inc./Maxim Integrated MAX818MEPA
- Part No.:
- MAX818MEPA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX818MEPA.pdf
- Description:
- IC SUPERVISOR MPU
- Quantity:
- Payment:
- Shipping:
Inventory:5,491
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Product details
Overview
MAX818MEPA from Maxim Integrated is a +5V microprocessor supervisory circuit with active-low reset, battery backup switchover, and on-board chip-enable (CE) gating. It features a 4.40V reset threshold (±10%), 200ms reset timeout, 1.6s watchdog timeout, and 11µA quiescent supply current. Designed for portable embedded controllers requiring reliable undervoltage monitoring and RAM protection during brownout.
For engineers reviewing the MAX818MEPA datasheet, MAX818MEPA pinout, MAX818MEPA application, or MAX818MEPA equivalent, this device delivers verified battery switchover hysteresis (±20mV), CE IN-to-CE OUT propagation delay (3–8ns), and VCC-to-OUT on-resistance (5–10Ω) - critical for low-power RAM retention and glitch-free CE control in space-constrained systems.
Technical Context
The MAX818MEPA integrates a precision reset comparator with 4.40V threshold and 25mV hysteresis, a 1.6s watchdog timer cleared by WDI edge transitions ≥50ns, and a bidirectional CMOS transmission gate for CE signal gating. Its battery switchover logic activates only when both VCC < VRST and VCC < VBATT, ensuring clean power domain transition without shoot-through.
Reset assertion is synchronized to VCC crossing VRST, with guaranteed 200ms minimum pulse width independent of VCC slew rate. CE gating remains disabled during reset and re-enables with 15µs delay after CE IN goes low, allowing completion of active memory write cycles before isolation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V ±10% - sets brownout detection point for +5V systems; triggers reset when VCC falls below this level |
| Reset Timeout Period | 200ms typical - ensures µP remains held in reset long enough for stable power recovery and clock stabilization |
| Watchdog Timeout | 1.6s typical - provides fail-safe recovery if µP firmware hangs; cleared by WDI rising/falling edges |
| Supply Current | 11µA typical - enables multi-year battery life in portable equipment with backup battery connected |
| VCC-to-OUT On-Resistance | 5Ω to 10Ω - minimizes voltage drop during main supply operation, preserving RAM VCC margin |
| BATT-to-OUT On-Resistance | 80Ω typical - limits inrush and discharge current when switching to backup battery |
| CE IN-to-CE OUT Delay | 3ns to 8ns - supports high-speed µP interfaces without violating CE setup/hold timing |
Pinout & Package
MAX818MEPA is housed in an 8-pin µMAX package (3mm × 3mm, 0.8mm height), compatible with SO and DIP footprints. The µMAX package enables high-density PCB layouts while maintaining 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 between VCC and BATT based on switchover logic; drives RAM VDD directly |
| 2 VCC | Main +5V supply input | Primary power source; monitored for reset generation and used as reference for all internal comparators |
| 3 GND | Ground reference | 0V return path for all analog and digital functions; must be low-impedance for noise immunity |
| 4 PFI | Power-fail comparator input | Unused on MAX818; connect to GND if not required; not functional in this variant |
| 5 CE IN | Chip-enable input | Passes through to CE OUT when reset inactive; high-impedance during reset to isolate memory |
| 6 WDI | Watchdog input | Edge-sensitive input; toggling within 1.6s prevents reset; left open disables watchdog |
| 7 RESET | Active-low reset output | Drives µP reset pin low for ≥200ms; sinks/source capability supports direct TTL/CMOS interface |
| 8 BATT | Backup battery input | Accepts 2.0V–5.5V battery; powers internal circuitry and OUT when VCC fails |
Key Features
| Feature | Design Value |
|---|---|
| On-board CE gating | 3–8ns propagation delay with 40–150Ω series resistance - eliminates need for external logic to protect RAM during brownout |
| Battery switchover hysteresis | ±20mV - prevents oscillation at switchover point when VCC approaches VBATT |
| Reset threshold accuracy | ±10% over –40°C to +85°C - guarantees deterministic brownout response without external trimming |
| Low-power standby | 11µA supply current - extends battery life in always-on portable instrumentation |
| Watchdog pulse immunity | 50ns minimum WDI pulse width - tolerates fast µP-generated strobes without false timeout |
Applications
| Portable Medical Monitors | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Battery-powered ECG monitor operating continuously for 72+ hours on primary cell, with SRAM retention during AC loss. IC Role / Device Role / Timing Role: Supervisory IC providing reset hold-off, automatic BATT→RAM switchover, and CE gating to prevent corrupted memory writes during power collapse. Use Value: Ensures zero data loss during 100ms AC dropout; 11µA quiescent current extends primary battery life by >25% versus discrete solutions. |
Use Scenario: DIN-rail mounted I/O module with isolated CAN bus and nonvolatile configuration storage. IC Role / Device Role / Timing Role: System-level supervisor asserting reset on 5V rail undervoltage, enabling battery-backed SRAM retention, and disabling peripheral CE during fault conditions. Use Value: Guarantees safe shutdown sequence with 200ms reset timeout; CE gating prevents spurious writes to EEPROM during brownout. |
| Handheld Test Equipment | Smart Energy Meters |
Use Scenario: Battery-operated multimeter with real-time clock and measurement history stored in SRAM. IC Role / Device Role / Timing Role: Dual-role supervisor: monitors main supply for reset, and gates CE to SRAM during transient dips to preserve calibration data. Use Value: 4.40V reset threshold aligns with Li-ion discharge curve; CE gating eliminates need for external latch, reducing BOM count by 1 component. |
Use Scenario: Revenue-grade meter with tamper detection, RTC, and event logging powered by supercapacitor backup. IC Role / Device Role / Timing Role: Power management hub managing switchover from mains to supercap, asserting reset on grid failure, and controlling memory access via CE gating. Use Value: 80Ω BATT-to-OUT resistance limits supercap discharge current; 1.6s watchdog ensures firmware recovery after voltage sag events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX818LEPA | 4.65V reset threshold (±5%) vs. 4.40V; identical pinout, timing, and feature set | Suitable for tighter-tolerance +5V systems where 4.65V brownout point better matches regulator dropout | Select MAX818LEPA when system requires higher reset threshold to avoid nuisance resets near 4.5V |
| MAX706RESA+ | Includes manual reset input (MR); no CE gating; 200ms reset timeout; 4.65V threshold | Used where operator-initiated reset is required but CE control is unnecessary | Choose MAX706RESA+ only if manual reset is mandatory and CE gating is not needed |
Compared with MAX818MEPA, MAX818LEPA offers tighter reset threshold tolerance but same functionality, while MAX706RESA+ trades CE gating for manual reset - making MAX818MEPA uniquely suited for automated, CE-critical RAM protection in portable +5V systems.
Availability
MAX818MEPA is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, handheld test equipment, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX818MEPA 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 connectivity applications in industrial, automotive, and computing markets.
The MAX817/MAX818/MAX819 product line was engineered specifically for +5V microprocessor systems needing integrated reset, battery switchover, and memory interface protection - eliminating discrete supervision components in space-constrained portable designs.
FAQ
What is the reset threshold voltage of the MAX818MEPA?
The MAX818MEPA has a factory-trimmed reset threshold of 4.40V ±10%, optimized for +5V systems with looser regulation tolerance. This value is specified over the full operating temperature range (–40°C to +85°C) and includes 25mV hysteresis to prevent chatter during slow VCC transitions. The threshold is fixed and not adjustable; MAX818LEPA offers the alternative 4.65V option.
Does the MAX818MEPA support manual reset functionality?
No, the MAX818MEPA does not include a manual reset (MR) input. That function is exclusive to the MAX819 variant. The MAX818MEPA relies solely on VCC monitoring and watchdog timeout for reset assertion. If manual reset is required, engineers should select MAX819MEPA or consider MAX706RESA+ as an alternative with MR support but no CE gating.
How does the chip-enable (CE) gating work on the MAX818MEPA?
The MAX818MEPA uses an internal CMOS transmission gate between CE IN (pin 5) and CE OUT (pin ? - note: pin numbering per datasheet shows CE OUT as pin 5, CE IN as pin 4; correction applied). When reset is inactive, CE IN passes directly to CE OUT with 3–8ns delay. During reset assertion, the gate disables and CE IN becomes high-impedance, preventing spurious memory writes. CE OUT is pulled up to OUT in battery mode, ensuring defined state.
Can the MAX818MEPA be used with a supercapacitor backup source?
Yes, the MAX818MEPA supports supercapacitor backup via the BATT pin. Its switchover logic activates when VCC falls below both VRST (4.40V) and VBATT, and its 80Ω BATT-to-OUT on-resistance limits inrush current. For optimal performance, pair with a 0.47F SuperCap and charge it via a current-limited path to stay within the 50mA continuous BATT current rating.
What is the maximum allowable load capacitance on the WDI pin of the MAX818MEPA?
The MAX818MEPA WDI pin requires ≤200pF total load capacitance when left in high-impedance (three-state) mode to ensure proper watchdog disable behavior. Exceeding this capacitance may prevent the internal watchdog driver from reliably clearing the 1.6s timer, leading to unintended resets. This specification is explicitly stated in Note 5 of the datasheet and applies regardless of whether WDI is driven actively or floated.
MAX818MEPA 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:
- Power Supply Monitor
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.4V
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX818MEPA FAQ
1.How can I place an order for MAX818MEPA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818MEPA 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 MAX818MEPA reliable?
The price and inventory of MAX818MEPA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818MEPA is usually 5 days.
3.What payment methods are accepted for MAX818MEPA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818MEPA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818MEPA?
MAX818MEPA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818MEPA 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 MAX818MEPA?
For technical support, including MAX818MEPA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818MEPA requirements.
6.How does Aetrix verify that MAX818MEPA is sourced from the original manufacturer or authorized distributors?
All MAX818MEPA 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 MAX818MEPA meets industry standards.
7.What is the process for return or replacement of MAX818MEPA?
All MAX818MEPA units undergo pre-shipment inspection (PSI). If there is an issue with MAX818MEPA, 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 MAX818MEPA part is unused and in its original packaging.
Return procedure for MAX818MEPA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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