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Analog Devices Inc./Maxim Integrated MAX805SCPA+
- Part No.:
- MAX805SCPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX805SCPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,056
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Product details
Overview
MAX805SCPA+ from Maxim Integrated is a 3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 2.925V reset threshold (S-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC supply integrity, asserts reset during brownout or watchdog timeout, and switches CMOS RAM to VBATT when VCC drops below 2.40V - used in embedded controllers and portable equipment requiring reliable power-up sequencing and data retention.
For engineers reviewing the MAX805SCPA+ datasheet, MAX805SCPA+ pinout, MAX805SCPA+ application, or MAX805SCPA+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases, and validated alternative parts for 3.0V/3.3V µP supervision with battery backup and power-fail warning.
Technical Context
This device integrates a precision reset comparator (±4% threshold tolerance), a non-disableable 1.6s watchdog timer cleared by WDI edges, and a dual-path power switch: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω NMOS. Switchover occurs at VSW = 2.40V (VBATT > VCC) on power-down and at VRST = 2.925V on power-up, ensuring stable VOUT reconnection after brownout recovery.
The PFI input compares against a 1.237V reference with 10mV hysteresis; PFO asserts low when PFI < VPFT or VCC < VSW. RESET is open-drain and requires external pull-up; MR is active-low with internal 70µA pull-up and 200ms deassertion delay. All logic inputs accept TTL/CMOS levels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (VCC falling), ±4% tolerance - ensures reset assertion before 3.3V supply drops below 2.85V system minimum. |
| Reset Timeout Period | 200ms (typical) - guarantees µP remains held in reset long enough for stable clock and supply settling. |
| Watchdog Timeout | 1.6s - detects µP lockup; timer clears on any WDI edge, preventing spurious resets during normal operation. |
| VCC Supply Current | 40µA (typ, VCC < 3.6V) - enables ultra-low-power operation in battery-backed systems over full temperature range. |
| Battery Supply Current | 1µA (max, C/E grade) - minimizes drain on lithium backup cells during extended standby. |
| VBATT-to-VOUT On-Resistance | 140Ω (typ) - limits voltage drop across backup path, supporting ≥2.0V VOUT for CMOS RAM retention. |
| Power-Fail Input Threshold | 1.237V ±20mV - provides accurate undervoltage detection for auxiliary rails via external resistor divider. |
Pinout & Package
MAX805SCPA+ 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), and thermal resistance is 9.09mW/°C above +70°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS); connects to RAM VDD to maintain data during brownout. |
| 2 - VCC | Main supply input | Primary 3.0V/3.3V power rail; powers internal circuitry and sources VOUT when active; absolute max = +6.0V. |
| 3 - GND | Ground reference | Common return for all analog and digital functions; substrate tied to higher of VCC/VBATT and must be floated in hybrid designs. |
| 4 - PFI | Power-fail input | Monitors auxiliary supply via resistor divider; triggers PFO low when voltage falls below 1.237V reference. |
| 5 - PFO | Power-fail output | Active-low open-drain signal; asserts when PFI < 1.237V or VCC < 2.40V; can drive MR on MAX704/MAX806. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); clears 1.6s timer on transition; tied high/low causes periodic reset every ~1.8s. |
| 7 - RESET | Active-high open-drain reset output | Inverse of MAX690-style RESET; requires external pull-up to VCC; sinks 1.2mA min at VOL ≤ 0.3V. |
| 8 - VBATT | Backup-battery input | Accepts up to 6.0V; may exceed VCC; supplies VOUT when VCC < 2.40V; leakage < 1µA ensures long battery life. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion down to VCC = 1V | Ensures fail-safe reset even during deep brownout, critical for systems with unregulated input stages. |
| Battery-backup switchover with 2.40V threshold | Enters backup mode before VOUT drops below 2.0V RAM retention limit, maximizing data hold time. |
| 200ms reset timeout with restart-on-brownout | Each VCC dip below 2.925V restarts the timer, preventing premature µP release during unstable supply conditions. |
| 1.237V PFI comparator with 10mV hysteresis | Rejects noise on monitored rails without external components; supports accurate multi-rail fault detection. |
| 40µA VCC supply current (typ) | Reduces quiescent load on primary supply, extending battery runtime in portable and remote applications. |
Applications
| Battery-Powered Embedded Controller | Portable Medical Instrument |
|---|---|
Use Scenario: A handheld glucose meter uses a 3.3V µP and SRAM to store calibration data and recent readings between battery changes. IC Role / Device Role / Timing Role: MAX805SCPA+ monitors main supply, asserts RESET during power-up/brownout, and switches SRAM to 3.6V lithium cell when VCC drops below 2.40V. Use Value: Guarantees RAM data retention for >24 hours on backup power while consuming only 1µA from the battery in standby. |
Use Scenario: An ECG monitor operates from rechargeable Li-ion and must retain patient waveform buffers during brief AC adapter disconnection. IC Role / Device Role / Timing Role: MAX805SCPA+ provides 200ms reset hold time, detects VCC sag via internal comparator, and activates VBATT switchover before VOUT falls below 2.0V. Use Value: Prevents waveform loss and µP corruption during transient power interruptions, meeting IEC 60601-1 reliability requirements. |
| Industrial Data Logger | Smart Sensor Node |
Use Scenario: A field-deployed temperature logger runs on primary 3.3V supply and includes a coin-cell backup for EEPROM write protection during power failure. IC Role / Device Role / Timing Role: MAX805SCPA+ watches VCC, triggers watchdog if µP hangs, asserts RESET on brownout, and routes VBATT to EEPROM VDD via VOUT. Use Value: Eliminates need for discrete reset IC + backup switch + watchdog, reducing BOM count and PCB area by 3 components. |
Use Scenario: A LoRaWAN sensor node sleeps most of the time but wakes periodically to sample and transmit; must preserve configuration across power cycles. IC Role / Device Role / Timing Role: MAX805SCPA+ holds µP in reset until VCC stabilizes post-wake, monitors supply health via PFI, and enables fast wake-up using MR input. Use Value: Achieves sub-100nA system sleep current by leveraging 1µA VBATT leakage and open-drain RESET for low-power wake signaling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX805TCSA+ | Reset threshold = 3.075V (T-suffix); same SO-8 package; identical features and timing. | Suitable for 3.3V ±5% systems where tighter upper threshold margin is required. | Select MAX805TCSA+ when VCC nominal is 3.3V with ≤5% tolerance and reset must not assert above 3.15V. |
| MAX805RCPA+ | Reset threshold = 2.625V (R-suffix); same PDIP-8 package; identical features and timing. | Optimized for 3.0V ±10% supplies; asserts reset later than S-version during gradual droop. | Choose MAX805RCPA+ for 3.0V systems needing extended hold-up time before reset assertion. |
Compared with MAX805SCPA+, the T-version offers higher reset threshold for tighter 3.3V regulation, while the R-version lowers threshold for wider 3.0V tolerance - all share identical watchdog, battery switchover, and PFI/PFO functionality, enabling direct substitution in layout with only threshold adjustment.
Availability
MAX805SCPA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply, RoHS-compliant packaging, and guaranteed long-term availability.
Supply support for MAX805SCPA+ 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, medical, communications, and computing applications.
The MAX805 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for reliable power-up sequencing, brownout protection, and battery-backed memory retention in 3.0V/3.3V embedded systems.
FAQ
What is the reset threshold voltage for MAX805SCPA+?
The MAX805SCPA+ has a nominal reset threshold of 2.925V (S-suffix), specified as 2.85V (min) to 3.00V (max) for VCC falling. This value is optimized for 3.3V ±10% power supplies, ensuring reset asserts before VCC drops below 2.85V while avoiding false triggers above 3.00V.
Does MAX805SCPA+ include a watchdog timer, and can it be disabled?
Yes, MAX805SCPA+ includes a 1.6s watchdog timer that cannot be disabled. The timer clears on any rising or falling edge at the WDI pin and triggers RESET if WDI remains static for >1.6s. This design prevents accidental watchdog disablement in safety-critical applications.
How does the battery switchover function work on MAX805SCPA+?
When VCC falls below 2.40V (VSW) and VBATT > VCC, MAX805SCPA+ disconnects VOUT from VCC and connects it to VBATT via a 140Ω internal switch. Upon VCC recovery, VOUT reconnects to VCC only after VCC rises above the 2.925V reset threshold - ensuring stable supply before RAM reconnection.
What is the function of the PFI and PFO pins on MAX805SCPA+?
PFI is a dedicated input compared to a 1.237V internal reference; PFO is its open-drain output. When PFI voltage falls below 1.237V or VCC drops below 2.40V, PFO goes low. This allows monitoring of auxiliary supplies (e.g., analog rails) using a simple resistor divider without affecting core supervision functions.
Is MAX805SCPA+ pin-compatible with other devices in the MAX80x family?
Yes, MAX805SCPA+ shares identical pinout and package (8-pin PDIP) with MAX802SCPA+, MAX804SCPA+, and MAX806SCPA+. Functionally, it matches MAX804SCPA+ except for RESET polarity (MAX804 is active-low push-pull; MAX805 is active-high open-drain), requiring external pull-up for proper operation.
MAX805SCPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.925V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX805SCPA+ FAQ
1.How can I place an order for MAX805SCPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805SCPA+ 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 MAX805SCPA+ reliable?
The price and inventory of MAX805SCPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805SCPA+ is usually 5 days.
3.What payment methods are accepted for MAX805SCPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805SCPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805SCPA+?
MAX805SCPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805SCPA+ 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 MAX805SCPA+?
For technical support, including MAX805SCPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805SCPA+ requirements.
6.How does Aetrix verify that MAX805SCPA+ is sourced from the original manufacturer or authorized distributors?
All MAX805SCPA+ 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 MAX805SCPA+ meets industry standards.
7.What is the process for return or replacement of MAX805SCPA+?
All MAX805SCPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX805SCPA+, 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 MAX805SCPA+ part is unused and in its original packaging.
Return procedure for MAX805SCPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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