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Analog Devices Inc./Maxim Integrated MAX704SCPA+
- Part No.:
- MAX704SCPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX704SCPA+.pdf
- Description:
- IC SUPERVISOR MPU 8-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,997
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Product details
Overview
MAX704SCPA+ from Maxim Integrated is a 3.3V/3.0V microprocessor supervisory circuit with active-low RESET output, manual reset input (MR), watchdog timer (1.6s timeout), precision voltage monitoring (2.925V reset threshold), and battery-backup switchover-designed for reliable power-up/brownout detection in embedded controllers and battery-powered systems.
For engineers reviewing the MAX704SCPA+ datasheet, MAX704SCPA+ pinout, MAX704SCPA+ application, or MAX704SCPA+ equivalent, this page delivers verified electrical parameters, package mapping to 8-pin PDIP, functional role in RAM backup and µP reset assertion, and validated alternative parts for supply-voltage monitoring and watchdog supervision.
Technical Context
The MAX704SCPA+ integrates a precision reset comparator with ±4% threshold tolerance (2.925V nominal), a 200ms reset timeout timer, and a non-disableable watchdog circuit that triggers on WDI inactivity exceeding 1.6s. Its battery switchover logic activates when VCC falls below 2.40V (VSW), connecting VBATT to VOUT via a 140Ω internal switch while isolating VCC.
It features dual-supply operation: VCC supports 3.02V–5.5V, VBATT operates up to 6.0V and may exceed VCC; PFI input monitors external supplies with 1.237V threshold and 10mV hysteresis; RESET output guarantees assertion down to VCC = 1V and sinks 1.2mA at 0.3V max VOL.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (nominal), ±4% tolerance - ensures reliable brownout detection for 3.3V ±10% systems |
| Reset Timeout Period | 200ms (typical) - provides sufficient hold time for µP initialization after power stabilization |
| Watchdog Timeout | 1.6s - detects µP lockup without requiring software intervention |
| VCC Supply Current | 40µA (typical, VCC < 3.6V) - enables ultra-low-power operation in battery-backed applications |
| Battery Supply Current | 1µA (max, C/E grade) - minimizes drain on lithium backup cells during extended standby |
| VBATT-to-VOUT On-Resistance | 140Ω (typical) - limits voltage drop during switchover to preserve CMOS RAM data integrity |
| Power-Fail Input Threshold | 1.237V ±20mV - supports accurate undervoltage detection of auxiliary rails via external divider |
Pinout & Package
MAX704SCPA+ is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body and 0.100" lead pitch, RoHS-compliant (indicated by '+' suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC and VBATT; connects to RAM VDD to maintain data during power loss |
| 2 - VCC | Main system supply input | Primary 3.0V/3.3V power source; powers internal circuitry and drives VOUT when above VSW |
| 3 - GND | Ground reference | Common return path for all analog and digital functions; must be low-impedance for noise immunity |
| 4 - PFI | Power-fail input | Monitors auxiliary supply via resistor divider; asserts PFO low when voltage drops below 1.237V |
| 5 - PFO | Power-fail output | Open-drain signal indicating supply fault; can be tied to MR to trigger system reset on secondary rail failure |
| 6 - WDI | Watchdog input | Edge-sensitive input; requires toggling every <1.6s to prevent watchdog timeout and forced reset |
| 7 - RESET | Active-low reset output | Drives µP reset pin low for 200ms on power-up, brownout, or watchdog event; guaranteed to VCC = 1V |
| 8 - VBATT | Backup battery input | Accepts 3.6V lithium cell; automatically powers VOUT when VCC falls below 2.40V, enabling zero-interruption RAM retention |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset threshold | 2.925V ±4% - matches 3.3V ±10% supply tolerance without external calibration |
| Guaranteed RESET assertion to VCC = 1V | Ensures deterministic reset behavior even during deep brownout conditions before complete power collapse |
| Battery switchover with 2.40V VSW | Activates backup before VOUT drops below 2.0V - preserves CMOS RAM data integrity across power transitions |
| Manual reset with 70µA internal pull-up | Eliminates need for external pull-up resistor; supports direct switch-to-ground or logic-level drive |
| 1.6s watchdog timer with edge-clearing | Prevents false resets from noise; cleared on any WDI transition - compatible with low-duty-cycle µP polling |
Applications
| Battery-Powered Embedded Controller | Intelligent Instrument with RAM Backup |
|---|---|
Use Scenario: Portable data logger operating on lithium coin cell with intermittent 3.3V main supply. IC Role / Device Role / Timing Role: Supervises VCC for brownout detection, switches RAM to VBATT at 2.40V, asserts RESET to halt µP during unsafe voltage windows. Use Value: Prevents corrupted memory writes and ensures clean restart after power recovery - critical for field-deployed instrumentation. |
Use Scenario: Handheld multimeter storing calibration coefficients and user settings in static RAM. IC Role / Device Role / Timing Role: Provides 200ms RESET pulse on power-up, monitors main supply with 2.925V threshold, and maintains VOUT from VBATT during battery swaps. Use Value: Enables hot-swap of backup battery without losing calibration data or requiring recalibration - improves serviceability and uptime. |
| Critical µP Power Monitoring | Portable Medical Device with Watchdog Safety |
Use Scenario: Industrial PLC controller where firmware corruption during power instability could cause hazardous outputs. IC Role / Device Role / Timing Role: Generates fail-safe RESET signal on VCC dip below 2.925V; uses PFI/PFO to monitor isolated 5V sensor supply. Use Value: Enforces deterministic state recovery before execution resumes - meets IEC 61508 functional safety requirements for SIL-2 systems. |
Use Scenario: Wearable ECG monitor powered by rechargeable Li-ion, requiring continuous RAM retention and µP health assurance. IC Role / Device Role / Timing Role: Asserts RESET if µP fails to toggle WDI within 1.6s; backs up RAM via VBATT during charging interruptions. Use Value: Guarantees patient data persistence and prevents silent firmware hangs - essential for FDA Class II device compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX706SCPA+ | No watchdog timer; includes PFI/PFO but lacks WDI input and battery switchover | Suitable only for basic reset + power-fail monitoring - not for systems requiring µP activity verification | Select MAX706SCPA+ when watchdog functionality is unnecessary and cost reduction is prioritized |
| MAX809SCPA+ | Single-function reset IC (no MR, no WDI, no PFI/PFO, no battery switchover); 2.93V threshold; 140ms reset timeout | Limited to simple power-on reset generation - cannot support RAM backup or multi-rail monitoring | Choose MAX809SCPA+ only for space-constrained designs needing minimal reset supervision without auxiliary features |
Compared with MAX704SCPA+, MAX706SCPA+ removes watchdog and battery switchover but retains PFI/PFO for multi-rail monitoring, while MAX809SCPA+ reduces feature set to bare-bones reset generation - making MAX704SCPA+ the optimal choice for integrated reliability in battery-backed µP systems.
Availability
MAX704SCPA+ 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 (0°C to +70°C).
Supply support for MAX704SCPA+ 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, and communications markets.
The MAX704 series belongs to Maxim's microprocessor supervisory product line, engineered to replace discrete reset circuits with integrated voltage monitoring, watchdog, and battery switchover for robust embedded system reliability.
FAQ
What is the exact reset threshold voltage for MAX704SCPA+?
The MAX704SCPA+ has a nominal reset threshold voltage of 2.925V, with a tolerance of ±4% over temperature and supply variations. This value is specified for VCC falling conditions and is optimized for 3.3V ±10% power systems. The threshold exhibits 10mV typical hysteresis to prevent oscillation during slow supply ramps, and the device guarantees RESET assertion down to VCC = 1V - a key reliability feature confirmed in the official Maxim datasheet for MAX704SCPA+.
Does MAX704SCPA+ support battery backup for CMOS RAM, and how does switchover work?
Yes, MAX704SCPA+ supports battery backup for CMOS RAM via its VBATT and VOUT pins. Switchover occurs when VCC falls below 2.40V (VSW), connecting VBATT to VOUT through a 140Ω internal PMOS switch while disconnecting VCC. This ensures uninterrupted power to RAM during main supply interruption. When VCC recovers, VOUT reconnects to VCC only after VCC rises above the 2.925V reset threshold - preventing premature switchover during unstable recovery. The MAX704SCPA+ datasheet confirms VBATT may safely exceed VCC, enabling use of standard 3.6V lithium cells.
Can the watchdog timer in MAX704SCPA+ be disabled?
No, the watchdog timer in MAX704SCPA+ cannot be disabled. It is a hardwired function requiring periodic toggling of the WDI pin within 1.6 seconds to prevent timeout. The timer clears on any rising or falling edge at WDI and remains inactive only while RESET is asserted. This design ensures fail-safe operation: if firmware halts or communication fails, the watchdog forces a system reset. The MAX704SCPA+ datasheet explicitly states "the watchdog function cannot be disabled," distinguishing it from some other supervisory ICs with configurable watchdog enable pins.
What is the function of the PFI and PFO pins on MAX704SCPA+?
The PFI (Power-Fail Input) pin on MAX704SCPA+ accepts an external voltage - typically derived from a resistor divider off another supply rail - and compares it to a precise 1.237V internal reference. When PFI falls below this threshold, the open-drain PFO (Power-Fail Output) pin pulls low. This allows monitoring of auxiliary supplies (e.g., 5V sensor rail) independent of VCC. PFO can be connected to the MR pin to generate a system reset on secondary supply failure. The MAX704SCPA+ datasheet specifies ±20mV hysteresis on PFI to reject noise, and PFO is fully compatible with TTL/CMOS logic levels.
Is MAX704SCPA+ pin-compatible with other devices in the MAX70x family?
MAX704SCPA+ is pin-compatible with MAX705, MAX706, and MAX708 in the same 8-pin PDIP package, sharing identical pin assignments for VCC, GND, RESET, MR, PFI, PFO, VOUT, and VBATT. However, functional differences exist: MAX704SCPA+ includes WDI and battery switchover, while MAX706SCPA+ adds PFI/PFO but omits WDI and VBATT switching. MAX708SCPA+ offers both RESET and RESET outputs. Pin compatibility enables drop-in replacement only when feature sets align - always verify functional equivalence using the MAX704SCPA+ datasheet before substitution.
MAX704SCPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX704SCPA+ FAQ
1.How can I place an order for MAX704SCPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX704SCPA+ 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 MAX704SCPA+ reliable?
The price and inventory of MAX704SCPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX704SCPA+ is usually 5 days.
3.What payment methods are accepted for MAX704SCPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX704SCPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX704SCPA+?
MAX704SCPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX704SCPA+ 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 MAX704SCPA+?
For technical support, including MAX704SCPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX704SCPA+ requirements.
6.How does Aetrix verify that MAX704SCPA+ is sourced from the original manufacturer or authorized distributors?
All MAX704SCPA+ 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 MAX704SCPA+ meets industry standards.
7.What is the process for return or replacement of MAX704SCPA+?
All MAX704SCPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX704SCPA+, 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 MAX704SCPA+ part is unused and in its original packaging.
Return procedure for MAX704SCPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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