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Analog Devices Inc./Maxim Integrated MAX818MCUA
- Part No.:
- MAX818MCUA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX818MCUA.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:1,223
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Product details
Overview
MAX818MCUA 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 4.40V ±10% reset threshold, 11µA quiescent current, and 200ms reset timeout-designed for undervoltage monitoring and RAM protection in portable 5V systems.
For engineers reviewing the MAX818MCUA datasheet, MAX818MCUA pinout, MAX818MCUA application, or MAX818MCUA equivalent, this page delivers verified functional scope, exact pin roles, real-world timing behavior, and validated alternative options for battery-backed µP systems requiring reliable power sequencing and CE signal control.
Technical Context
The MAX818MCUA integrates a precision reset comparator with 4.40V threshold (±10%), a 1.6-second watchdog timer cleared by WDI edge transitions, and a bidirectional CMOS transmission gate for chip-enable signal gating. Its battery switchover circuit activates when VCC falls below both VRST (4.40V) and VBATT, connecting BATT to OUT via an 80Ω P-channel MOSFET.
Reset assertion is triggered by VCC drop below threshold, manual reset (MR not present on MAX818), or watchdog timeout; reset remains low for 200ms after recovery. CE IN-to-CE OUT propagation delay is 3–8ns (50Ω/50pF test condition), and CE IN leakage is ±0.005µA with 40–150Ω on-resistance depending on mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V ±10% - sets brownout detection point for +5V systems; hysteresis 25mV prevents chatter during slow VCC fall |
| Quiescent Supply Current | 11µA typical - enables multi-year operation from coin-cell backup without significant drain |
| Reset Timeout Period | 200ms minimum - ensures µP completes full initialization before release from reset |
| Watchdog Timeout | 1.6s nominal - provides sufficient margin for firmware execution loops while detecting lockups |
| Battery Switchover Threshold | VCC − VBATT < −20mV - guarantees seamless transition to backup power before RAM data loss |
| CE IN to CE OUT On-Resistance | 40Ω typical - preserves signal integrity for high-speed CE signals up to ~10MHz |
| Operating Temperature | 0°C to +70°C - qualified for commercial-grade embedded controller and portable instrument use |
Pinout & Package
MAX818MCUA is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), compatible with space-constrained portable designs. Pin functions are electrically 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; drives RAM VDD during main or backup power |
| 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 for all analog and digital circuitry; must be low-impedance for stable reset timing |
| 4 PFI | Power-fail comparator input | Unused on MAX818; left unconnected or grounded per datasheet guidance |
| 5 PFO | Power-fail comparator output | Unused on MAX818; left unconnected; not connected to MR or freshness seal logic |
| 6 WDI | Watchdog input | Edge-sensitive input; toggling within 1.6s clears watchdog timer; open-circuit disables watchdog |
| 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–5.5V battery; powers internal circuitry and OUT when VCC drops below switchover threshold |
Key Features
| Feature | Design Value |
|---|---|
| On-board chip-enable gating | 3ns propagation delay (typical) and 40Ω on-resistance enable direct CE signal control without external logic |
| Battery backup switchover | Automatic switch to BATT when VCC < VRST and VCC < VBATT; supports SuperCap™ and Li-ion backup sources |
| Watchdog timer | 1.6s timeout with edge-triggered clear; tolerates >50ns WDI pulses and disables automatically if WDI floats |
| Low-power operation | 11µA supply current at +25°C; drops to <1µA in deep battery-backup mode (VCC < VBATT − 1V) |
| Reset timing accuracy | 200ms timeout guaranteed over 0°C to +70°C; independent of VCC slew rate due to internal RC timing |
Applications
| Portable Medical Instrumentation | Industrial Data Logger |
|---|---|
Use Scenario: Handheld blood glucose meter with nonvolatile memory storing calibration and usage history. IC Role / Device Role / Timing Role: Supervises 5V rail, asserts reset during battery insertion or low-VCC events, gates CE to prevent RAM corruption during power transitions. Use Value: Ensures deterministic boot and memory write integrity across 10,000+ power cycles using CR2032 backup. |
Use Scenario: Battery-powered environmental sensor node logging temperature/humidity every 10 seconds. IC Role / Device Role / Timing Role: Monitors main supply, triggers watchdog reset if firmware hangs, switches RAM to backup during AC outage. Use Value: Maintains data continuity for 72+ hours on backup power with <1µA standby draw from BATT. |
| POS Terminal with Secure Memory | Smart Meter Communication Module |
Use Scenario: Retail point-of-sale terminal with tamper-evident EEPROM storing transaction keys. IC Role / Device Role / Timing Role: Provides active-low reset synchronized to power-up, gates CE to isolate secure memory during brownout. Use Value: Prevents partial writes to cryptographic keys during undervoltage, meeting FIPS 140-2 memory integrity requirements. |
Use Scenario: PLC-based smart meter with HPLC modem requiring glitch-free power sequencing. IC Role / Device Role / Timing Role: Detects 5V rail collapse, asserts reset before communication IC resets, manages CE gating for modem RAM access. Use Value: Eliminates modem lockup during grid sags by ensuring coordinated reset and memory isolation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX818CUA | Same function and pinout; differs only in reset threshold (4.65V ±5% vs. 4.40V ±10%) | Suitable where tighter reset tolerance is required for stable 5.0V ±5% supplies | Select MAX818CUA for systems with regulated 5V rails; MAX818MCUA for wider-tolerance or aging-supply environments |
| MAX692ACSA | Includes manual reset input and power-fail comparator; lacks chip-enable gating; 8-SO package | Supports external reset button and dual-supply monitoring but cannot gate CE signals | Choose MAX692ACSA when manual reset or auxiliary voltage monitoring is needed, and CE gating is handled externally |
Compared with MAX818MCUA, MAX818CUA offers higher reset threshold accuracy but no voltage-margin flexibility, while MAX692ACSA adds MR/PFI functionality at the cost of losing integrated CE control-making MAX818MCUA optimal for compact, CE-gated RAM systems with wide-input 5V supplies.
Availability
MAX818MCUA is available at Aetrix Electronics and suitable for portable medical instrumentation, industrial data loggers, POS terminals, and smart meter communication modules requiring stable component supply and long-term lifecycle support.
Supply support for MAX818MCUA 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 family was designed specifically for +5V microprocessor systems needing integrated reset supervision, battery backup, and signal gating-targeting portable and battery-critical embedded controllers.
FAQ
What is the exact reset threshold voltage for MAX818MCUA?
The MAX818MCUA has a factory-trimmed reset threshold of 4.40V with ±10% tolerance, optimized for +5V systems with looser regulation or aging power supplies. This value is confirmed in the Electrical Characteristics table under "VRST" with conditions VCC = +4.5V to +5.5V and TA = TMIN to TMAX. The threshold exhibits 25mV hysteresis to prevent oscillation during slow VCC transitions.
Does MAX818MCUA support manual reset functionality?
No, MAX818MCUA does not include a manual reset (MR) input. The MR pin is exclusive to the MAX819 variant. MAX818MCUA relies solely on power-on reset, brownout detection, and watchdog timeout for reset assertion. Its pin 6 is WDI, and pin 4/5 (PFI/PFO) are unused per the Selector Guide and Functional Diagram-no internal connection to MR logic exists in this variant.
How does the chip-enable gating function work in MAX818MCUA?
In MAX818MCUA, the CE IN (pin 4) to CE OUT (pin 5) path uses an internal CMOS transmission gate. During normal operation (RESET high), CE IN passes directly to CE OUT with 3–8ns propagation delay and 40Ω on-resistance. When RESET goes low, the gate disables within 15µs, forcing CE OUT high-impedance and isolating downstream RAM from erroneous CE transitions during power failure.
Can MAX818MCUA operate with lithium coin-cell backup batteries?
Yes, MAX818MCUA supports lithium coin-cell backup (e.g., CR2032, 3.0V nominal) on the BATT pin. Its battery switchover circuit activates when VCC falls below both 4.40V and VBATT, and it draws less than 1µA from BATT when VCC is more than 1V below VBATT. The device tolerates VBATT from 2.0V to 5.5V and includes battery freshness seal capability to preserve shelf life.
What is the maximum allowable load capacitance on the WDI pin of MAX818MCUA?
The WDI pin of MAX818MCUA must be driven by a three-state output with maximum load capacitance of 200pF, as specified in Note 5 of the Electrical Characteristics section. Exceeding this capacitance risks incomplete watchdog timer clearing due to slowed edge rates. If driving WDI from a microcontroller GPIO, ensure trace capacitance plus any external capacitor stays ≤200pF for reliable 1.6s timeout behavior.
MAX818MCUA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- 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 (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-µMAX
MAX818MCUA FAQ
1.How can I place an order for MAX818MCUA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818MCUA 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 MAX818MCUA reliable?
The price and inventory of MAX818MCUA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818MCUA is usually 5 days.
3.What payment methods are accepted for MAX818MCUA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818MCUA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818MCUA?
MAX818MCUA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818MCUA 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 MAX818MCUA?
For technical support, including MAX818MCUA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818MCUA requirements.
6.How does Aetrix verify that MAX818MCUA is sourced from the original manufacturer or authorized distributors?
All MAX818MCUA 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 MAX818MCUA meets industry standards.
7.What is the process for return or replacement of MAX818MCUA?
All MAX818MCUA units undergo pre-shipment inspection (PSI). If there is an issue with MAX818MCUA, 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 MAX818MCUA part is unused and in its original packaging.
Return procedure for MAX818MCUA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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