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Analog Devices Inc./Maxim Integrated MAX805REPA+
- Part No.:
- MAX805REPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX805REPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:241
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Product details
Overview
MAX805REPA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-high open-drain RESET output, precision 2.625V reset threshold (±4% tolerance), 200ms reset timeout, 1.6s watchdog timer, and battery-backup switchover capability. It monitors VCC for brownout detection, asserts reset during power-up/down, and supports CMOS RAM retention via VOUT switching between VCC and VBATT - used in embedded controllers and portable equipment requiring reliable power sequencing.
For engineers reviewing the MAX805REPA+ datasheet, MAX805REPA+ pinout, MAX805REPA+ application, or MAX805REPA+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative parts - all grounded in Maxim's official electrical characteristics and typical operating circuits for the R-suffix variant in 8-pin SO package.
Technical Context
The MAX805REPA+ integrates a precision reset comparator with 2.625V nominal threshold (VCC rising: 2.55V–2.72V), a 1.6s watchdog timer cleared by WDI edges, and a bidirectional battery switchover circuit that connects VOUT to VBATT when VCC falls below 2.40V (VSW) and VBATT > VCC. Its PFI input monitors auxiliary supplies at 1.237V ±10mV, while RESET remains high-impedance until asserted.
It operates across –40°C to +85°C, draws only 40µA from VCC (typical at VCC < 3.6V), and guarantees RESET assertion down to VCC = 1.0V. The device uses internal PMOS switches: 3Ω VCC-to-VOUT path and 140Ω VBATT-to-VOUT path, enabling low-dropout backup power delivery to static RAM without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V (nominal), ±4% tolerance - ensures reliable reset assertion before VCC drops below 2.55V in 3.0V systems with ±10% supply tolerance. |
| Reset Timeout Period | 200ms (min 140ms, max 280ms) - provides sufficient hold time for µP initialization after power stabilization. |
| Watchdog Timeout | 1.6s (min 1.12s, max 2.24s) - detects µP lockup without requiring software intervention or external timing elements. |
| VCC Supply Current | 40µA (typical, VCC < 3.6V) - enables long battery life in always-on monitoring applications. |
| Battery Supply Current | 0.4–1µA (max) - minimizes drain on lithium backup cells during extended standby. |
| VBATT-to-VOUT On-Resistance | 140Ω (typical at +25°C) - limits voltage drop under 1mA load, preserving RAM data integrity during switchover. |
| PFO Input Threshold | 1.237V ±10mV - supports accurate power-fail detection of auxiliary rails via external resistor divider. |
Pinout & Package
MAX805REPA+ is supplied in an 8-pin SOIC package (RoHS-compliant, + suffix), with 1.27mm pitch and standard JEDEC MS-012 outline. Pin 1 is marked with a dot or bevelled corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches automatically between VCC and VBATT; connects to VBATT (via 140Ω switch) when VCC < 2.40V, ensuring uninterrupted RAM power. |
| 2 - VCC | Main system supply input | Accepts 2.72V–5.5V; powers internal circuitry and enables VOUT-to-VCC connection (3Ω switch) when above reset threshold. |
| 3 - GND | Ground reference | Common return for all analog and digital functions; substrate tied to higher of VCC/VBATT - must remain floating in hybrid designs. |
| 4 - PFI | Power-fail input | Compares against 1.237V reference; asserts PFO low when input falls below threshold - used to monitor secondary supplies. |
| 5 - PFO | Power-fail output | Open-drain, active-low signal; can drive MR on MAX704/MAX806 to trigger system reset upon auxiliary rail failure. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); clears 1.6s timer on transition - no pull-up/pull-down required; cannot be disabled. |
| 7 - RESET | Active-high, open-drain reset output | Inverse of MAX690/704/802 RESET; requires external pull-up to VCC; asserts high for 200ms after fault or MR release. |
| 8 - VBATT | Backup-battery input | Accepts up to 6.0V; may exceed VCC in normal operation - enables use of 3.6V lithium coin cells without level-shifting. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset behavior even during deep brownout conditions where other supervisors lose functionality. |
| Battery-backup switchover with 2.40V VSW threshold | Enters battery mode early enough to preserve CMOS RAM data (>2.0V), while avoiding premature switchover that shortens battery life. |
| 1.6s watchdog timer with edge-triggered clear | Eliminates need for external RC timing networks and prevents false timeouts due to noise on WDI line. |
| 40µA VCC supply current (typical) | Reduces quiescent power in always-on monitoring circuits - critical for battery-powered portable instrumentation. |
| ±4% reset threshold accuracy (R-suffix) | Meets tight tolerance requirements for 3.0V ±10% systems, guaranteeing reset before supply falls below 2.55V. |
Applications
| Battery-Powered Embedded Controller | Portable Medical Instrument |
|---|---|
Use Scenario: Microcontroller-based glucose meter powered by CR2032 lithium coin cell, requiring RAM retention during battery replacement. IC Role / Device Role / Timing Role: Supervisory IC providing VOUT switchover, brownout reset, and watchdog supervision - ensures deterministic boot and data integrity. Use Value: Enables hot-swap battery replacement without RAM loss or µP crash, leveraging 2.40V VSW and 140Ω VBATT-to-VOUT switch. |
Use Scenario: Handheld ECG device with dual-supply architecture (3.3V main, 5V display backlight), needing auxiliary rail monitoring. IC Role / Device Role / Timing Role: Power-fail detector using PFI/PFO to flag 5V rail collapse and trigger controlled shutdown via MR. Use Value: Prevents corrupted waveform storage by asserting reset within 200ms of 5V failure, using PFO-to-MR coupling. |
| Industrial Data Logger | Smart Sensor Node |
Use Scenario: Remote environmental sensor logging temperature/humidity to flash memory, powered by solar-charged Li-ion. IC Role / Device Role / Timing Role: Brownout protector and watchdog supervisor - resets µP if firmware hangs or supply dips below 2.625V. Use Value: Eliminates field failures caused by undervoltage-induced code corruption, using guaranteed 200ms reset pulse. |
Use Scenario: LoRaWAN node with intermittent wake-up cycles, relying on ultra-low-quiescent-current supervision. IC Role / Device Role / Timing Role: Low-power supervisor enabling multi-year battery life - draws only 40µA from VCC and sub-1µA from VBATT. Use Value: Extends operational lifetime beyond 5 years on single AA cell, validated across –40°C to +85°C industrial range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX804REPA+ | Active-low RESET output (push-pull), identical reset threshold, watchdog, and switchover specs. | Requires external pull-up for µP reset input compatibility; not suitable for systems needing open-drain active-high RESET. | Select MAX804REPA+ only when interfacing with legacy µPs expecting active-low reset assertion. |
| MAX805TEPA+ | Higher 3.075V reset threshold (±4%), same package and pinout - otherwise functionally identical. | Designed for 3.3V ±5% systems; asserts reset earlier than R-suffix during marginal supply droop. | Choose MAX805TEPA+ for applications where tighter supply regulation demands earlier reset intervention. |
Compared with MAX805REPA+, MAX804REPA+ offers push-pull active-low reset (requiring different µP interface), while MAX805TEPA+ shifts reset threshold upward by 450mV - both retain identical watchdog, battery switchover, and low-power performance, making them direct functional alternatives for design reuse or supply margin tuning.
Availability
MAX805REPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply across industrial temperature ranges.
Supply support for MAX805REPA+ 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, mixed-signal, and power management ICs for industrial, automotive, and computing applications.
The MAX805 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust power monitoring and fail-safe reset generation in 3.0V/3.3V embedded systems with battery backup requirements.
FAQ
What is the exact reset threshold voltage for MAX805REPA+?
The MAX805REPA+ has a nominal reset threshold of 2.625V, with a guaranteed range of 2.55V to 2.72V for VCC rising (per datasheet Electrical Characteristics table). This R-suffix variant is optimized for 3.0V ±10% systems, asserting reset before VCC falls below 2.55V to prevent µP malfunction during brownout.
Does MAX805REPA+ support battery voltage higher than VCC?
Yes, MAX805REPA+ explicitly supports VBATT exceeding VCC - up to 6.0V - enabling direct connection of 3.6V lithium coin cells without regulators or diodes. The internal switchover circuit activates when VCC falls below 2.40V (VSW), connecting VBATT to VOUT regardless of relative voltage magnitude.
How does the watchdog timer in MAX805REPA+ operate?
The MAX805REPA+ watchdog timer has a fixed 1.6s timeout (1.12–2.24s over temperature). It clears on any WDI edge (rising or falling) and triggers RESET if no transition occurs within that window. Unlike older families, the watchdog cannot be disabled - ensuring continuous supervision of µP firmware execution.
What is the function of the PFI and PFO pins on MAX805REPA+?
PFI is a dedicated 1.237V ±10mV comparator input for monitoring auxiliary supplies (e.g., 5V rail via resistor divider); PFO is its open-drain, active-low output. When PFI falls below threshold or VCC drops below VSW, PFO goes low - it can be wired to MR on compatible parts like MAX704 to initiate system reset.
Can MAX805REPA+ operate without a backup battery?
Yes, MAX805REPA+ functions without VBATT: connect both VBATT and VOUT pins to VCC. However, battery-backup features (RAM retention, switchover) are disabled. For pure supervision without backup, consider MAX706R or MAX708R - but MAX805REPA+ remains fully operational for reset, watchdog, and PFI/PFO functions.
MAX805REPA+ 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:
- 2.625V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX805REPA+ FAQ
1.How can I place an order for MAX805REPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805REPA+ 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 MAX805REPA+ reliable?
The price and inventory of MAX805REPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805REPA+ is usually 5 days.
3.What payment methods are accepted for MAX805REPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805REPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805REPA+?
MAX805REPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805REPA+ 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 MAX805REPA+?
For technical support, including MAX805REPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805REPA+ requirements.
6.How does Aetrix verify that MAX805REPA+ is sourced from the original manufacturer or authorized distributors?
All MAX805REPA+ 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 MAX805REPA+ meets industry standards.
7.What is the process for return or replacement of MAX805REPA+?
All MAX805REPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX805REPA+, 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 MAX805REPA+ part is unused and in its original packaging.
Return procedure for MAX805REPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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