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Analog Devices Inc./Maxim Integrated MAX805LESA+T
- Part No.:
- MAX805LESA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX805LESA+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,194
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Product details
Overview
The MAX805LESA+T from Maxim Integrated is a microprocessor supervisory circuit providing active-high reset, battery-backup switchover, watchdog timer, and power-fail detection for +5V systems. It asserts RESET at 4.65V threshold with 200ms pulse width, operates down to VCC = 1.1V, draws only 200µA quiescent current, and supports lithium battery backup up to 4.80V. It is used in critical μP power monitoring for industrial controllers and intelligent instruments.
For engineers reviewing the MAX805LESA+T datasheet, MAX805LESA+T pinout, MAX805LESA+T application, or MAX805LESA+T equivalent, key selection criteria include active-high reset compatibility (e.g., Intel 80C51), guaranteed reset assertion below 1.1V, ±2% power-fail accuracy, 1.6s watchdog timeout, and SO-8 lead-free packaging with -40°C to +85°C operation.
Technical Context
The MAX805LESA+T integrates four independent functions: a precision 4.65V reset monitor with 200ms delay, a 1.6s watchdog timer cleared by WDI edges or reset assertion, a 1.25V reference-based power-fail comparator (PFI/PFO), and a battery switchover circuit that connects VBATT to VOUT only when VCC falls below 4.65V and VBATT exceeds VCC by >20mV.
Its active-high RESET output is electrically inverted from the standard RESET signal and guaranteed functional down to VCC = 1.1V. The internal PMOS switch provides 5Ω on-resistance when VCC powers VOUT and 80Ω when VBATT powers VOUT, with <1µA standby current in full battery-backup mode when VCC < VBATT − 1V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - triggers reset during brownout or power-up when VCC drops below or rises above this level. |
| Reset Pulse Width | 200ms nominal - ensures reliable μP initialization without requiring external timing components. |
| Watchdog Timeout | 1.6s ±0.65s - detects software lockup if WDI is not toggled within this window. |
| Supply Current (Active) | 200–500µA - enables low-power operation in battery-backed embedded systems. |
| Battery-Backup Current | ≤1µA when VCC < VBATT − 1V - extends lithium battery life beyond 10 years in standby. |
| Power-Fail Accuracy | ±2% (at +25°C) - guarantees precise early-warning detection of supply degradation before system failure. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade reliability in harsh environments. |
Pinout & Package
MAX805LESA+T is housed in an 8-pin SOIC package (SO-8, 150mil width) with RoHS-compliant lead-free finish. Pin 1 is VBATT; pin 2 is VCC; pin 3 is GND; pin 4 is PFI; pin 5 is PFO; pin 6 is WDI; pin 7 is RESET (active-high); pin 8 is VOUT.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VBATT (Pin 1) | Backup-battery input | Accepts 2.8–4.8V lithium battery; enables automatic switchover to VOUT when VCC fails. |
| VCC (Pin 2) | +5V main supply input | Primary power source; powers internal circuitry and drives VOUT via 5Ω PMOS switch. |
| GND (Pin 3) | Ground reference | Common return path for all analog and digital functions; must be low-impedance. |
| PFI (Pin 4) | Power-fail comparator input | Monitors divided-down supply voltage against 1.25V internal reference for early warning. |
| PFO (Pin 5) | Power-fail output | Open-drain active-low signal indicating supply undervoltage condition. |
| WDI (Pin 6) | Watchdog input | Edge-sensitive trigger; resets watchdog timer on rising/falling transitions; floating disables watchdog. |
| RESET (Pin 7) | Active-high reset output | Push-pull output asserted high during reset; compatible with Intel 80C51 and other active-high μP reset inputs. |
| VOUT (Pin 8) | CMOS RAM supply output | Switches between VCC and VBATT to maintain RAM data during power loss; 5Ω/80Ω on-resistance. |
Key Features
| Feature | Design Value |
|---|---|
| Active-high RESET output | Guaranteed valid down to VCC = 1.1V - eliminates need for external level-shifting for 80C51-family μPs. |
| Low-quiescent-current battery mode | <1µA supply draw when VCC < VBATT − 1V - enables multi-year backup with CR2032 cells. |
| Guaranteed reset assertion at low VCC | RESET remains logic-high until VCC ≥ 1.1V - prevents premature release during brownout recovery. |
| Integrated 1.25V precision reference | Used for both PFI comparison and internal reset threshold generation - eliminates external reference IC. |
| Controlled battery switchover hysteresis | 40mV (20mV up/down) - prevents oscillation during slow VCC droop or rise near reset threshold. |
Applications
| Battery-Powered Industrial Controller | Intelligent Instrument Data Logger |
|---|---|
Use Scenario: Programmable logic controller retains configuration and real-time clock during AC mains interruption using a 3.6V lithium coin cell. IC Role / Device Role / Timing Role: MAX805LESA+T monitors +5V rail, asserts RESET to halt CPU, switches VOUT to VBATT, and signals power-fail via PFO to initiate graceful shutdown. Use Value: Prevents RAM corruption and firmware crash during 100ms–2s outages; extends battery life >8 years via sub-1µA backup current. |
Use Scenario: Portable gas analyzer stores sensor calibration data and timestamps in CMOS RAM during field operation with intermittent power. IC Role / Device Role / Timing Role: MAX805LESA+T provides active-high RESET compatible with its ARM Cortex-M0 host, detects supply sag via PFI, and maintains VOUT during battery-only operation. Use Value: Ensures deterministic boot sequence after power restoration; eliminates need for external supervisor or reset buffer IC. |
| Critical μP Power Monitoring | Embedded Telematics Unit |
Use Scenario: Railway signaling module requires fail-safe restart on any supply anomaly to meet SIL-2 functional safety requirements. IC Role / Device Role / Timing Role: MAX805LESA+T generates 200ms RESET pulse on VCC drop below 4.65V, feeds watchdog timer from MCU GPIO, and flags undervoltage via PFO interrupt. Use Value: Meets IEC 61508 timing constraints for reset assertion; ±2% PFI accuracy ensures early fault detection before logic errors occur. |
Use Scenario: In-vehicle telematics gateway uses supercapacitor backup and must retain GPS position and CAN message buffers during engine cranking dips. IC Role / Device Role / Timing Role: MAX805LESA+T monitors 5V DC-DC output, activates VBATT switchover at 4.65V, and holds RESET until stable post-cranking. Use Value: Maintains CAN bus synchronization and prevents packet loss during 4.2–4.8V brownouts typical of automotive cold-crank events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX805LCSA | Same functionality and pinout, but rated for 0°C to +70°C industrial temperature range instead of −40°C to +85°C. | Suitable for commercial-grade equipment with controlled ambient; not qualified for extended industrial thermal cycling. | Select MAX805LCSA only if operating environment stays within 0–70°C and cost sensitivity outweighs long-term reliability needs. |
| MAX813LESA+ | Provides identical 4.65V reset threshold and 200ms pulse width, but features active-low RESET (not RESET) and no battery switchover. | Applicable where active-low reset is required and backup RAM is not needed - reduces BOM count in simpler designs. | Choose MAX813LESA+ only when battery backup is unnecessary and μP accepts active-low reset; MAX805LESA+T is irreplaceable for active-high + backup use cases. |
Compared with MAX805LCSA and MAX813LESA+, the MAX805LESA+T uniquely combines −40°C to +85°C operation, active-high RESET, and integrated battery switchover - making it the sole option for ruggedized, battery-backed μP systems requiring Intel-compatible reset signaling.
Availability
MAX805LESA+T is available at Aetrix Electronics and suitable for battery-powered industrial controllers, intelligent instrument data loggers, critical μP power monitoring, embedded telematics units, and railway signaling modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX805LESA+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 industrial, communications, and computing applications, with emphasis on power management, sensing, and interface solutions.
The MAX805L series belongs to Maxim's microprocessor supervisory product line, engineered specifically to replace discrete reset circuits and improve system reliability in +5V μP systems requiring active-high reset, battery backup, and power-fail warning.
FAQ
What is the reset threshold voltage of the MAX805LESA+T?
The MAX805LESA+T has a nominal reset threshold voltage of 4.65V, with a guaranteed tolerance of ±150mV over the full −40°C to +85°C temperature range. This threshold applies to both power-up assertion and brownout detection, and the device guarantees RESET remains asserted until VCC rises above this level and holds for 200ms thereafter.
Does the MAX805LESA+T support active-high reset for Intel 80C51 microcontrollers?
Yes, the MAX805LESA+T provides an active-high RESET output (pin 7) explicitly designed for μPs like the Intel 80C51 that require high-level reset assertion. Unlike the standard RESET output found on MAX690A/MAX802L, the RESET output is guaranteed functional down to VCC = 1.1V, ensuring robust reset behavior during marginal supply conditions.
What is the maximum allowable backup battery voltage for the MAX805LESA+T?
The MAX805LESA+T supports a maximum backup battery voltage of 4.80V at the VBATT pin (pin 1). This limit ensures safe operation of the internal battery switchover circuitry and prevents substrate diode conduction when VCC approaches the reset threshold. Lithium batteries with open-circuit voltages between 2.8V and 3.6V are ideal and may be connected directly without additional regulation.
How does the watchdog timer function on the MAX805LESA+T?
The MAX805LESA+T incorporates a 1.6s watchdog timer that triggers RESET if the WDI pin (pin 6) remains static (high or low) for longer than the timeout period. The timer clears on any WDI edge transition, reset assertion, or high-impedance (three-state) condition. When disabled (e.g., WDI left floating), the watchdog is inactive and does not affect system operation.
What package type and environmental rating does the MAX805LESA+T have?
The MAX805LESA+T is supplied in an 8-pin SOIC (SO-8) package with lead-free finish (+ suffix), compliant with RoHS directives. It is rated for operation from −40°C to +85°C, making it suitable for industrial and extended-temperature applications. The package outline conforms to JEDEC MS-012AA standards with 150mil body width and 1.27mm lead pitch.
MAX805LESA+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:
- Push-Pull, Totem Pole
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX805LESA+T FAQ
1.How can I place an order for MAX805LESA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805LESA+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 MAX805LESA+T reliable?
The price and inventory of MAX805LESA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805LESA+T is usually 5 days.
3.What payment methods are accepted for MAX805LESA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805LESA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805LESA+T?
MAX805LESA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805LESA+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 MAX805LESA+T?
For technical support, including MAX805LESA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805LESA+T requirements.
6.How does Aetrix verify that MAX805LESA+T is sourced from the original manufacturer or authorized distributors?
All MAX805LESA+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 MAX805LESA+T meets industry standards.
7.What is the process for return or replacement of MAX805LESA+T?
All MAX805LESA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX805LESA+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 MAX805LESA+T part is unused and in its original packaging.
Return procedure for MAX805LESA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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