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Analog Devices Inc./Maxim Integrated MAX802MEPA+
- Part No.:
- MAX802MEPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX802MEPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:715
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Product details
Overview
MAX802MEPA+ from Maxim Integrated is a microprocessor supervisory IC providing reset generation, battery-backup switchover, watchdog timer, and power-fail detection for +5V systems. It asserts active-low RESET during power-up, brownout (VCC < 4.40V), and watchdog timeout (1.6s), delivers VOUT from VCC or VBATT via internal PMOS switches, and features ±2% power-fail accuracy. Used in industrial controllers requiring reliable cold-start and backup-RAM retention.
For engineers reviewing the MAX802MEPA+ datasheet, MAX802MEPA+ pinout, MAX802MEPA+ application, or MAX802MEPA+ equivalent, key selection criteria include its 4.40V reset threshold, 200ms reset pulse width, 50nA battery-backup quiescent current, guaranteed RESET assertion down to VCC = 1V, and compatibility with lithium backup batteries up to 4.55V.
Technical Context
The MAX802MEPA+ integrates four independent functional blocks: a precision voltage monitor with 4.40V reset threshold and 40mV hysteresis; a 1.6s watchdog timer cleared by WDI edge transitions; a dual-path power switch (5Ω VCC-to-VOUT, 80Ω VBATT-to-VOUT) activated only when VCC falls below reset threshold; and a 1.25V reference-based power-fail comparator (PFI/PFO) with 400ns response time and ±2% accuracy over temperature.
Its reset generator guarantees logic-low output for ≥200ms after VCC rises above 4.40V and remains asserted while VCC < 1V. Battery switchover operates with 20mV turn-on/turn-off thresholds and 40mV hysteresis to prevent oscillation during slow VCC decay, and the device draws only 50nA from VBATT when VCC = 0V and VBATT = 2.8V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V nominal; triggers RESET when VCC drops below this level - ensures reliable brownout detection for +5V systems |
| Reset Pulse Width | 200ms typical; holds μP in reset long enough for stable clock and supply settling after power recovery |
| Watchdog Timeout | 1.6s nominal; detects software lockup if WDI is not toggled - prevents system hang without external intervention |
| Battery-Backup Current | 50nA max at TA = +25°C; minimizes lithium battery drain during extended power loss |
| Power-Fail Accuracy | ±2% over temperature; enables precise early-warning detection of supply degradation before reset threshold is reached |
| VCC Operating Range | 1.2V to 5.5V; supports valid RESET assertion down to 1.2V - critical for low-voltage brownout immunity |
| VBATT Max Voltage | 4.55V absolute maximum; defines safe lithium battery selection limit to avoid substrate diode conduction |
Pinout & Package
MAX802MEPA+ is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body and through-hole mounting. Pin spacing is 0.100", lead finish is lead-free (RoHS-compliant) per the "+" suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 5Ω PMOS) and VBATT (via 80Ω PMOS) based on VCC vs. reset threshold - preserves RAM data during power failure |
| 2 - VCC | +5V main supply input | Primary power source; powers internal circuitry and drives VOUT when above 4.40V - must be monitored for reset initiation |
| 3 - GND | Ground reference | Common return path for all analog and digital functions - requires low-impedance connection to minimize noise coupling into PFI/WDI |
| 4 - PFI | Power-fail comparator input | Monitors divided-down supply voltage against 1.25V internal reference - enables customizable undervoltage warning before reset |
| 5 - PFO | Power-fail comparator output | Active-low open-drain signal indicating PFI < 1.25V - used to trigger μP interrupt or initiate graceful shutdown sequence |
| 6 - WDI | Watchdog timer input | Edge-sensitive input; reset triggered if no transition occurs within 1.6s - requires periodic firmware toggle to confirm software liveness |
| 7 - RESET | Active-low reset output | Push-pull output asserting logic low for ≥200ms during power-up, brownout, or watchdog timeout - directly interfaces to μP reset pin |
| 8 - VBATT | Backup battery input | Source for VOUT during VCC failure; switchover enabled only when VCC < 4.40V and VBATT > VCC + 20mV - prevents unnecessary battery discharge |
Key Features
| Feature | Design Value |
|---|---|
| Precision 4.40V reset threshold | Guaranteed 4.25V–4.50V range over -40°C to +85°C - eliminates need for external resistor divider in standard +5V applications |
| 200ms reset pulse width | Internally timed; independent of external capacitor - ensures consistent reset duration across production units and temperature |
| 80Ω VBATT-to-VOUT switch | Enables use of low-leakage lithium batteries while limiting backup current to <1μA when VCC < VBATT − 1V - extends battery life beyond 10 years |
| 400ns power-fail comparator response | Fast detection of supply droop - allows μP to save critical data before VCC crosses reset threshold |
| Guaranteed RESET down to VCC = 1.2V | Ensures reset remains asserted during deep brownout - prevents μP from executing corrupted code at marginal supply levels |
Applications
| Industrial PLCs | Medical Diagnostic Equipment |
|---|---|
Use Scenario: Programmable logic controller operating in factory environments with fluctuating AC line voltage and frequent power interruptions. IC Role / Device Role / Timing Role: Supervisory IC monitoring +5V rail, asserting RESET during brownouts, switching RAM to lithium backup, and signaling power-fail via PFO to initiate I/O state freeze. Use Value: Prevents control logic corruption and preserves process state across outages - enabling deterministic restart without manual intervention. | Use Scenario: Portable ultrasound unit powered by rechargeable Li-ion with requirement for zero-data-loss RAM retention during battery swaps. IC Role / Device Role / Timing Role: Provides 200ms reset hold time on power-up, monitors main DC-DC output for early fail indication, and seamlessly transfers VOUT from main supply to backup cell when VCC drops below 4.40V. Use Value: Eliminates need for external switchover MOSFET and discrete reset generator - reducing BOM count and PCB area while meeting IEC 62304 safety requirements. |
| Smart Energy Meters | Ruggedized Handheld Terminals |
Use Scenario: ANSI C12.20-compliant electricity meter deployed in outdoor substations subject to lightning-induced surges and wide ambient temperature swings (-40°C to +85°C). IC Role / Device Role / Timing Role: Generates robust reset signal immune to fast transients, uses PFI to detect pre-failure voltage sag on metering ASIC supply, and maintains SRAM integrity using 3.6V lithium coin cell. Use Value: Achieves ±2% power-fail accuracy over full temperature range - enabling accurate energy logging during grid instability events. | Use Scenario: Warehouse inventory terminal with barcode scanner, operating on intermittent AC power and requiring instant resume after brief outages. IC Role / Device Role / Timing Role: Monitors 5V system rail, asserts RESET on any dip below 4.40V, activates watchdog to catch firmware hangs, and powers real-time clock + SRAM from VBATT during outage. Use Value: Guarantees 50nA battery drain in backup mode - supporting >5-year coin-cell life without maintenance, even with daily power cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802MESA | Same electrical specs and pinout; SO-8 package instead of PDIP - 5.0mm × 4.0mm footprint, surface-mount assembly | Preferred for space-constrained PCBs or automated SMT lines; lacks through-hole mechanical stability for high-vibration environments | Select MAX802MESA when board space or assembly method favors SOIC; verify thermal derating (471mW max at +70°C) matches system airflow. |
| MAX692AESA | Identical 4.40V reset threshold and 1.6s watchdog, but lacks ±2% power-fail accuracy guarantee and has higher 200µA quiescent current | Suitable for cost-sensitive designs where PFI/PFO accuracy is non-critical and battery life is not constrained | Choose MAX692AESA only if PFO accuracy tolerance >±2% is acceptable and backup runtime requirements allow 4000× higher VBATT current than MAX802MEPA+. |
Compared with MAX802MESA, MAX802MEPA+ offers superior mechanical reliability in shock/vibration environments due to through-hole leads, while MAX692AESA trades guaranteed PFI accuracy and ultra-low backup current for lower unit cost - making MAX802MEPA+ optimal for long-life, safety-critical industrial deployments.
Availability
MAX802MEPA+ is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostic equipment, smart energy meters, and ruggedized handheld terminals requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for MAX802MEPA+ 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, automotive, and communications applications, with emphasis on high-reliability power management and interface solutions.
The MAX802M series belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust power-monitoring and battery-backed memory retention in harsh environments where supply stability cannot be assumed.
FAQ
What is the guaranteed minimum VCC level at which MAX802MEPA+ asserts RESET?
MAX802MEPA+ guarantees RESET assertion down to VCC = 1.2V over its full operating temperature range of -40°C to +85°C. This ensures the microprocessor remains held in reset during deep brownout conditions where supply voltage collapses gradually, preventing execution of invalid instructions. The specification is verified per Electrical Characteristics table on page 2 of the datasheet under "RESET Output Voltage" test conditions for MAX69_AE/M and MAX802_E devices.
Does MAX802MEPA+ support active-high reset outputs?
No, MAX802MEPA+ provides only active-low RESET output (pin 7). It does not include the active-high RESET output found on the MAX805L variant. For systems requiring active-high reset, the MAX805L or MAX690A should be selected instead. The MAX802MEPA+ datasheet explicitly states that the RESET pin is active-low and makes no provision for inversion or complementary output - confirmed in Pin Description (page 5) and Detailed Description (page 6).
What is the maximum allowable VBATT voltage for MAX802MEPA+?
The maximum allowable VBATT voltage for MAX802MEPA+ is 4.55V, as specified in Table 2 (page 7) of the datasheet under "Allowable Backup-Battery Voltages". Exceeding this voltage risks forward-biasing the internal substrate diode (D1 in Figure 3), causing uncontrolled current flow from VBATT to VCC when VCC approaches the reset threshold. This limitation applies regardless of whether a lithium coin cell or supercapacitor is used as the backup source.
How does the watchdog timer in MAX802MEPA+ get cleared?
The watchdog timer in MAX802MEPA+ is cleared by any rising or falling edge on the WDI pin (pin 6), by assertion of the RESET output, or by three-stating WDI (high-impedance). The timer restarts immediately upon release of RESET or when WDI transitions from high-impedance to driven state. This behavior is documented in the "Watchdog Input" section (page 6) and confirmed in the timing diagram (Figure 2), where WDI edge sensitivity and reset synchronization are explicitly defined.
Can MAX802MEPA+ monitor negative supply rails?
Yes, MAX802MEPA+ can monitor negative supply rails using an external resistor network as shown in Figure 7 (page 8) of the datasheet. The PFI input compares against an internal 1.25V reference, so a voltage divider configured to present +1.25V to PFI when the negative rail reaches its trip point enables detection. Accuracy depends on resistor tolerance and PFI input current (≤25nA), and the circuit requires connection to VCC and GND - no modification to MAX802MEPA+ itself is needed.
MAX802MEPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.4V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX802MEPA+ FAQ
1.How can I place an order for MAX802MEPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX802MEPA+ 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 MAX802MEPA+ reliable?
The price and inventory of MAX802MEPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX802MEPA+ is usually 5 days.
3.What payment methods are accepted for MAX802MEPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX802MEPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX802MEPA+?
MAX802MEPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX802MEPA+ 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 MAX802MEPA+?
For technical support, including MAX802MEPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX802MEPA+ requirements.
6.How does Aetrix verify that MAX802MEPA+ is sourced from the original manufacturer or authorized distributors?
All MAX802MEPA+ 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 MAX802MEPA+ meets industry standards.
7.What is the process for return or replacement of MAX802MEPA+?
All MAX802MEPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX802MEPA+, 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 MAX802MEPA+ part is unused and in its original packaging.
Return procedure for MAX802MEPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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