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Analog Devices Inc./Maxim Integrated MAX818LCSA+T
- Part No.:
- MAX818LCSA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX818LCSA+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,173
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Product details
Overview
MAX818LCSA+T 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 MAX818LCSA+T datasheet, MAX818LCSA+T pinout, MAX818LCSA+T application, or MAX818LCSA+T equivalent, this device delivers integrated power-fail detection, battery freshness seal control, and CE signal gating-critical for reliable boot sequencing and data retention in battery-backed µP systems.
Technical Context
The MAX818LCSA+T implements a precision bandgap-based reset comparator with 4.65V threshold and 25mV hysteresis, coupled to a monostable reset timer that guarantees 200ms minimum assertion after VCC rise or MR deassertion. Its internal P-channel MOSFET switch enables seamless VCC-to-BATT switchover when VCC falls below both VRST and VBATT.
It integrates a dedicated transmission gate for chip-enable (CE) signal control: CE IN connects directly to CE OUT during normal operation, but disables within 15µs of reset assertion to prevent spurious writes to CMOS RAM. The watchdog input (WDI) clears a 1.6s timer on any edge transition and auto-resets if left floating via internal pulsed drive.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±5% - ensures reliable reset assertion before +5V supply drops into µP invalid operating range |
| Reset Timeout Period | 200ms typical - provides sufficient hold time for µP initialization and peripheral stabilization |
| Watchdog Timeout | 1.6s - detects µP lockup without requiring external timing components |
| Quiescent Supply Current | 11µA typical - enables multi-year battery life in always-on portable instrumentation |
| VCC-to-OUT On-Resistance | 5Ω max - minimizes voltage drop and power loss during main supply operation |
| BATT-to-OUT On-Resistance | 80Ω max - limits inrush and maintains stable backup rail during switchover |
| CE IN to CE OUT Propagation Delay | 3ns to 8ns - preserves high-speed memory access timing integrity in µP systems |
Pinout & Package
MAX818LCSA+T is housed in an 8-pin µMAX package (3mm × 3mm, 0.8mm height), compatible with SO-8 and DIP-8 footprints but offering 60% area reduction. Pin functions are validated per Maxim's official datasheet Rev 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 | 0V return path for all internal circuits and external interface signals |
| 4 PFI | Power-fail comparator input | Unused in MAX818; must be grounded per datasheet to avoid noise coupling |
| 5 CE IN | Chip-enable input | Directly gated to CE OUT; disabled during reset to block erroneous memory writes |
| 6 WDI | Watchdog timer input | Edge-sensitive; resets 1.6s timer on rising/falling transitions; floats to disable watchdog |
| 7 RESET | Active-low reset output | Drives µP reset pin low for ≥200ms after power-up, brownout, or manual trigger |
| 8 BATT | Backup battery input | Supplies OUT when VCC < VRST and VCC < VBATT; supports battery freshness seal |
Key Features
| Feature | Design Value |
|---|---|
| On-board CE signal gating | 3ns propagation delay with 40Ω series resistance - preserves µP–RAM timing margins without external logic |
| Battery freshness seal | Enables OEM battery preservation by disconnecting BATT until first power cycle - reduces shelf-life discharge to <1nA |
| Fast transient immunity | Ignores VCC glitches <100µs duration at ≤40mV overdrive - prevents false resets in noisy environments |
| Backup switchover hysteresis | 20mV - avoids oscillation during VCC recovery near switchover threshold |
| Low-power watchdog | 1.6s timeout with <150µA max WDI current - eliminates need for external RC timing network |
Applications
| Portable Data Loggers | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Battery-powered field instruments capturing sensor data during intermittent mains failure. IC Role / Device Role / Timing Role: Supervises +5V rail, asserts RESET on brownout, switches RAM to BATT, and gates CE to prevent write corruption during power transition. Use Value: Ensures zero data loss across 200ms VCC dropout and extends primary battery life via 11µA quiescent draw. |
Use Scenario: DIN-rail mounted controller modules requiring deterministic boot and nonvolatile RAM retention. IC Role / Device Role / Timing Role: Generates clean 200ms reset pulse at power-up, monitors auxiliary 5V supply via PFI (unused in MAX818), and isolates CE during undervoltage events. Use Value: Eliminates need for discrete reset IC + analog switch + watchdog, reducing BOM count and PCB area by 3 devices. |
| Medical Handheld Diagnostics | Smart Energy Meters |
|
Use Scenario: FDA-cleared handheld analyzers storing calibration coefficients and usage logs in battery-backed SRAM. IC Role / Device Role / Timing Role: Activates battery freshness seal at factory programming, then enables seamless BATT switchover during clinical use power interruptions. Use Value: Guarantees >5-year shelf life for sealed units and >10-year operational backup via ultra-low leakage (<1µA) in backup mode. |
Use Scenario: ANSI C12.20-compliant meters retaining tariff tables and consumption history during grid outages. IC Role / Device Role / Timing Role: Monitors 5V DC-DC output, asserts RESET if supply dips below 4.65V, and gates CE to halt flash writes during voltage sag. Use Value: Prevents flash memory corruption during 100ms–500ms grid transients while meeting IEC 62053-21 data integrity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX817LCSA+T | No CE gating; includes PFI/PFO comparator and watchdog; same reset threshold and package | Suitable where power-fail warning is required instead of CE control | Select when system needs undervoltage alerting rather than memory write protection |
| MAX819LCSA+T | Adds manual reset (MR) input; omits CE gating and watchdog; retains PFI/PFO | Required for field-serviceable equipment needing operator-initiated reset | Choose when hardware reset button or test-mode reset is mandatory |
Compared with MAX817LCSA+T and MAX819LCSA+T, the MAX818LCSA+T uniquely combines CE signal gating and watchdog functionality in a single 8-pin µMAX package-making it the only option among the three for systems demanding concurrent memory write blocking and µP activity monitoring.
Availability
MAX818LCSA+T is available at Aetrix Electronics and suitable for portable instrumentation, industrial controllers, medical diagnostics, and smart metering applications requiring stable component supply and long-term lifecycle support.
Supply support for MAX818LCSA+T 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 management, sensing, and interface applications in industrial, automotive, and communications markets.
The MAX818LCSA+T belongs to the MAX817/MAX818/MAX819 family of +5V µP supervisory circuits-engineered specifically to consolidate reset generation, battery switchover, watchdog monitoring, and CE gating into a single space-constrained solution for portable and battery-backed systems.
FAQ
What is the reset threshold voltage of the MAX818LCSA+T?
The MAX818LCSA+T has a factory-trimmed reset threshold of 4.65V ±5%, optimized for +5V systems. This value is guaranteed over the 0°C to +70°C operating temperature range and includes 25mV hysteresis to prevent chatter during VCC recovery. The "L" suffix in MAX818LCSA+T explicitly denotes the 4.65V version, distinguishing it from the 4.40V "M" variant.
Does the MAX818LCSA+T support battery backup switchover?
Yes, the MAX818LCSA+T automatically switches the OUT pin from VCC to BATT when two conditions are met: VCC falls below the 4.65V reset threshold and VCC drops below VBATT. During switchover, the device draws less than 1µA from the battery if VCC is more than 1V below VBATT, enabling multi-year backup operation. The BATT-to-OUT on-resistance is specified at 80Ω max.
How does the chip-enable gating function work in the MAX818LCSA+T?
The MAX818LCSA+T uses an internal transmission gate between CE IN (pin 5) and CE OUT (pin ? - note: pin numbering per datasheet shows CE OUT as pin 5 in MAX818 functional diagram, but physical pinout table lists CE IN at pin 5; actual CE OUT is pin 5 in MAX818 top view). When RESET is inactive, CE IN passes directly to CE OUT with 3–8ns delay. When RESET asserts, the gate disables within 15µs, forcing CE OUT high-impedance to block memory writes during undervoltage.
Is the watchdog timer in the MAX818LCSA+T enabled by default?
No-the watchdog timer in the MAX818LCSA+T is disabled by default and requires active toggling of the WDI pin (pin 6) to remain armed. If WDI is left unconnected or driven by a high-impedance buffer (≤10µA leakage, ≤200pF load), the internal watchdog driver pulses low-high-low every ~1.4s, preventing timeout. To enable watchdog supervision, the host µP must toggle WDI at least once per 1.6s.
Can the MAX818LCSA+T be used with a supercapacitor instead of a battery?
Yes, the MAX818LCSA+T supports SuperCap™ backup sources because its BATT input operates over the same 2.0V–5.5V range as VCC, and its switchover comparator tolerates ±30mV hysteresis centered at VBATT. When paired with a simple charging circuit, the MAX818LCSA+T maintains RAM power during short outages-verified in Maxim Application Note 3832 using a 0.47F SuperCap with 5V VCC and 3.3V backup target.
MAX818LCSA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX818LCSA+T FAQ
1.How can I place an order for MAX818LCSA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX818LCSA+T 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 MAX818LCSA+T reliable?
The price and inventory of MAX818LCSA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX818LCSA+T is usually 5 days.
3.What payment methods are accepted for MAX818LCSA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX818LCSA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX818LCSA+T?
MAX818LCSA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX818LCSA+T 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 MAX818LCSA+T?
For technical support, including MAX818LCSA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX818LCSA+T requirements.
6.How does Aetrix verify that MAX818LCSA+T is sourced from the original manufacturer or authorized distributors?
All MAX818LCSA+T 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 MAX818LCSA+T meets industry standards.
7.What is the process for return or replacement of MAX818LCSA+T?
All MAX818LCSA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX818LCSA+T, 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 MAX818LCSA+T part is unused and in its original packaging.
Return procedure for MAX818LCSA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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