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Analog Devices Inc./Maxim Integrated MAX818MCSA+
- Part No.:
- MAX818MCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX818MCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:174
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Product details
Overview
MAX818MCSA+ 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 4.40V reset threshold (±10%), 200ms reset timeout, and 11µA quiescent current - designed for undervoltage monitoring and RAM protection in portable embedded controllers.
For engineers reviewing the MAX818MCSA+ datasheet, MAX818MCSA+ pinout, MAX818MCSA+ application, or MAX818MCSA+ 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 brownout recovery in space-constrained 5V systems.
Technical Context
The MAX818MCSA+ integrates a precision reset comparator with 4.40V threshold and 25mV hysteresis, a 1.6-second watchdog timer cleared by WDI edge transitions, and a bidirectional CMOS transmission gate for chip-enable (CE) signal control. Its battery switchover circuit uses internal P-channel MOSFETs to switch OUT between VCC and BATT based on voltage comparison (VCC vs. VBATT), with 80Ω BATT-to-OUT on-resistance and 5Ω VCC-to-OUT on-resistance.
It implements a battery freshness seal via CE OUT latching during power-down, enabling OEMs to preserve backup battery life until first use. The CE gating path provides 3ns propagation delay (typical), 40Ω series resistance, and automatic disable during reset assertion - ensuring RAM write completion before CE deactivation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V ±10% - triggers reset when VCC drops below nominal +5V supply, supporting tolerant 5V system designs. |
| Reset Timeout Period | 200ms - guarantees µP remains held in reset long enough for stable power-up and clock stabilization. |
| Watchdog Timeout | 1.6s - detects µP lockup or software hang; reset cleared by any WDI edge within this window. |
| Quiescent Supply Current | 11µA - enables multi-year battery operation in portable instruments and remote sensors. |
| BATT-to-OUT On-Resistance | 80Ω - limits voltage drop during battery-backup mode, preserving RAM retention voltage under load. |
| VCC-to-OUT On-Resistance | 5Ω - minimizes dropout during main supply operation, supporting up to 250mA output current. |
| CE IN to CE OUT Propagation Delay | 3ns - allows direct interfacing with high-speed µPs without timing violation in CE-controlled memory access. |
Pinout & Package
MAX818MCSA+ is housed in an 8-pin µMAX package (3mm × 3mm, 0.8mm height), compatible with SO and DIP footprints. Pin assignments are validated per Maxim's official datasheet Rev 3 (12/05).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Supply Output | Switched output connected to VCC or BATT; powers CMOS RAM during main/battery operation. |
| 2 VCC | Main Supply Input | +5V system rail input; powers internal circuitry and enables VCC-to-OUT switching above reset threshold. |
| 3 GND | Ground Reference | 0V reference for all analog comparators, reset logic, and CE gating circuitry. |
| 4 PFI | Power-Fail Input | Unused in MAX818; must be grounded per datasheet to avoid floating comparator input. |
| 5 CE IN | Chip-Enable Input | Input to CE transmission gate; low during write cycles to prevent erroneous RAM access during reset. |
| 6 WDI | Watchdog Input | Edge-sensitive input; toggling within 1.6s prevents reset; left unconnected disables watchdog. |
| 7 RESET | Active-Low Reset Output | Open-drain output asserting low for ≥200ms after VCC rise or WDI timeout; sinks 3.2mA min. |
| 8 BATT | Backup Battery Input | Accepts 2.0V–5.5V battery; connects to OUT when VCC falls below VBATT and reset threshold. |
Key Features
| Feature | Design Value |
|---|---|
| On-board CE gating | 3ns propagation delay and 40Ω series resistance enable direct µP–RAM interface without external logic. |
| Battery freshness seal | Latched via CE OUT during power-down sequence - preserves battery shelf life until first product use. |
| Fast transient immunity | Designed to ignore VCC transients <100µs duration, preventing false resets in noisy power environments. |
| Low-power battery switchover | Draws <1µA from BATT when VCC is >1V below VBATT - extends backup runtime in long-idle applications. |
| Integrated watchdog timer | 1.6s timeout with auto-clear on WDI edge - eliminates need for external timing components or firmware polling. |
Applications
| Portable Medical Sensors | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Battery-powered glucose meters and pulse oximeters requiring guaranteed boot integrity and RAM retention during battery swaps. IC Role / Device Role / Timing Role: Supervisory IC providing 200ms reset hold, 4.40V brownout detection, and seamless BATT→VCC switchover for SRAM backup. Use Value: Prevents data corruption during low-battery conditions and ensures deterministic startup after cold boot or battery replacement. |
Use Scenario: DIN-rail mounted programmable logic controllers operating in factory environments with unstable 5V rails. IC Role / Device Role / Timing Role: Active-low reset generator with 1.6s watchdog supervision and CE gating to protect configuration EEPROM writes during voltage sags. Use Value: Eliminates spurious reboots and memory corruption caused by 10–100ms line dips, improving system uptime and field reliability. |
| Smart Energy Meters | Embedded Point-of-Sale Terminals |
Use Scenario: ANSI C12.22-compliant electricity meters with nonvolatile timekeeping and tariff storage. IC Role / Device Role / Timing Role: Dual-role supervisor: reset controller during AC loss and battery-freshness seal enabler for supercapacitor-backed RTC. Use Value: Extends supercap lifetime by >5 years via sealed battery mode, while guaranteeing accurate timekeeping across 100,000+ power cycles. |
Use Scenario: Compact retail terminals using flash-based firmware and SRAM caches for transaction buffering. IC Role / Device Role / Timing Role: Chip-enable gatekeeper that blocks CE during reset assertion, preventing partial writes to flash memory during brownout. Use Value: Ensures atomic firmware updates and transaction logs - eliminating "bricked" units due to interrupted power events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX818LCSA+ | 4.65V reset threshold (±5%) instead of 4.40V; identical pinout, timing, and feature set. | Suitable for tighter-tolerance +5V supplies where 4.65V trip point better matches regulator dropout. | Select MAX818LCSA+ when system VCC regulation holds within ±5%; otherwise retain MAX818MCSA+ for ±10% margin. |
| MAX706RCSA+ | No CE gating or battery freshness seal; adds manual reset input and power-fail comparator (PFI/PFO). | Better suited for systems needing external reset button or dual-supply monitoring, but lacks RAM protection gating. | Choose MAX706RCSA+ only if manual reset or auxiliary voltage monitoring is required - not for CE-controlled memory systems. |
Compared with MAX818LCSA+, MAX818MCSA+ offers lower reset threshold tolerance for wider 5V supply variation; compared with MAX706RCSA+, it provides unique CE gating and battery seal functionality essential for RAM-critical portable designs - neither alternative replicates its full feature set.
Availability
MAX818MCSA+ is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart energy meters, and embedded point-of-sale terminals requiring stable component supply across extended production lifecycles.
Supply support for MAX818MCSA+ 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 - with emphasis on high-reliability, low-power solutions for industrial and medical markets.
The MAX818MCSA+ belongs to Maxim's microprocessor supervisory product line, engineered specifically to replace discrete reset + watchdog + battery-switch circuits in space-constrained +5V embedded systems.
FAQ
What is the reset threshold voltage of the MAX818MCSA+?
The MAX818MCSA+ has a factory-trimmed reset threshold of 4.40V ±10%, optimized for standard +5V systems with looser regulation tolerance. This value is specified over the full operating temperature range (0°C to +70°C) and includes 25mV hysteresis to prevent chatter near the trip point. The threshold is fixed and not adjustable - MAX818MCSA+ does not support external resistor programming.
Does the MAX818MCSA+ support manual reset functionality?
No, the MAX818MCSA+ does not include a manual reset (MR) input. That function is exclusive to the MAX819 variant. The MAX818MCSA+ relies solely on power-on reset, watchdog timeout, and brownout detection for reset generation. If manual reset capability is required, the MAX819MCSA+ or MAX819LCSA+ must be used instead - these share the same package and pinout but add the MR pin (Pin 6).
How does the chip-enable gating work in the MAX818MCSA+?
The MAX818MCSA+ uses an internal CMOS transmission gate between CE IN (Pin 5) and CE OUT (Pin 4) to block memory access during reset. When RESET is asserted, the gate disables and CE OUT goes high-impedance; if CE IN is low at reset assertion, CE OUT remains low for 15µs to complete the current write cycle. This behavior is confirmed in the functional diagram and timing figures of the MAX818MCSA+ datasheet.
Can the MAX818MCSA+ monitor a secondary voltage rail like +3.3V?
No - the MAX818MCSA+ does not include a dedicated power-fail comparator (PFI/PFO). That feature is present only in the MAX817 and MAX819 variants. The MAX818MCSA+ has no PFI pin (Pin 4 is NC and must be grounded), so it cannot generate warnings for auxiliary rails. For dual-rail monitoring, use MAX817MCSA+ or MAX819MCSA+ instead.
What is the maximum continuous current the MAX818MCSA+ can deliver from its OUT pin?
The MAX818MCSA+ supports up to 250mA continuous output current from the OUT pin when powered from VCC, with a typical VCC-to-OUT on-resistance of 5Ω. In battery-backup mode, the BATT-to-OUT path supports 50mA continuous current (80Ω on-resistance). Exceeding 250mA risks thermal shutdown or permanent damage - the absolute maximum rating for OUT is 250mA continuous, 1A peak for <100ns.
MAX818MCSA+ 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:
- 4.4V
- Output:
- -
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX818MCSA+ FAQ
1.How can I place an order for MAX818MCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818MCSA+ 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 MAX818MCSA+ reliable?
The price and inventory of MAX818MCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818MCSA+ is usually 5 days.
3.What payment methods are accepted for MAX818MCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818MCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818MCSA+?
MAX818MCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818MCSA+ 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 MAX818MCSA+?
For technical support, including MAX818MCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818MCSA+ requirements.
6.How does Aetrix verify that MAX818MCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX818MCSA+ 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 MAX818MCSA+ meets industry standards.
7.What is the process for return or replacement of MAX818MCSA+?
All MAX818MCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX818MCSA+, 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 MAX818MCSA+ part is unused and in its original packaging.
Return procedure for MAX818MCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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