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Analog Devices Inc./Maxim Integrated MAX804RCSA+
- Part No.:
- MAX804RCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX804RCSA+.pdf
- Description:
- IC SUPERVISOR MPU 8-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,684
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Product details
Overview
MAX804RCSA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 2.625V reset threshold (R-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC for brownout detection, asserts reset during power-up/down, and supports CMOS RAM backup in portable controllers and embedded systems.
For engineers reviewing the MAX804RCSA+ datasheet, MAX804RCSA+ pinout, MAX804RCSA+ application, or MAX804RCSA+ equivalent, this page delivers verified functional specifications, validated pin roles, confirmed battery-switching behavior, and real-world design implications for low-power µP supervision in 3V systems.
Technical Context
The MAX804RCSA+ integrates a precision reset comparator with ±2% tolerance on 2.625V threshold, a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path power switch: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω NMOS. Its PFI input accepts external voltage dividers for auxiliary supply monitoring.
It operates across –40°C to +85°C (E-grade), draws only 40µA from VCC at <3.6V, and guarantees RESET assertion down to VCC = 1V. Battery leakage is limited to ≤0.5µA, and VOUT maintains regulation within VCC–0.15V at 50mA load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V (±2%) - precisely triggers reset before 3.0V system drops below 2.59V, ensuring reliable brownout detection. |
| Reset Timeout Period | 200ms (140–280ms) - holds RESET asserted long enough to fully initialize µP after power recovery. |
| Watchdog Timeout | 1.6s (1.12–2.24s) - detects µP lockup without requiring software intervention or external timing components. |
| VCC Supply Current | 40µA (typ) at VCC < 3.6V - enables multi-year operation in battery-backed portable equipment. |
| Battery Supply Current | 0.4–1µA - minimizes drain on lithium coin cells during extended backup mode. |
| VOUT Output Voltage | VCC – 0.15V at 50mA - sustains CMOS RAM data retention even under moderate load during switchover. |
| Power-Fail Input Threshold | 1.237V ±20mV - provides accurate undervoltage warning for secondary supplies via resistor divider. |
Pinout & Package
MAX804RCSA+ is housed in an 8-pin SOIC package (SO) with lead-free finish (+ suffix), RoHS-compliant, and rated for –40°C to +85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Backup power output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS); powers CMOS RAM during brownout. |
| 2 - VCC | Main supply input | Primary 3.0V/3.3V system rail; powers internal circuitry and enables VOUT connection when above reset threshold. |
| 3 - GND | Ground reference | Common return path for all analog and digital functions; substrate tied to higher of VCC/VBATT. |
| 4 - PFI | Power-fail input | Monitors auxiliary supply via external divider; asserts PFO low when input falls below 1.237V. |
| 5 - PFO | Power-fail output | Active-low open-drain signal indicating PFI undervoltage or VCC falling below switchover threshold (2.40V). |
| 6 - WDI | Watchdog input | Edge-sensitive input; resets watchdog timer on rising/falling transition; timeout triggers RESET if idle ≥1.6s. |
| 7 - RESET | Active-high reset output | Open-drain output; pulled high externally; asserts logic high during reset condition (VCC < 2.625V or WDI timeout). |
| 8 - VBATT | Battery backup input | Accepts 3.6V lithium cell; may exceed VCC; connects to VOUT when VCC falls below 2.40V or 1.75V. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset initiation even during deep brownout, critical for data integrity in low-voltage recovery. |
| Battery can exceed VCC in normal operation | Enables direct use of 3.6V lithium cells without level-shifting, simplifying backup power architecture. |
| 200ms reset time delay with hysteresis | Prevents chatter during marginal VCC recovery by enforcing minimum deassertion hold time after threshold crossing. |
| 40µA VCC supply current | Reduces quiescent power in always-on supervision circuits, extending battery life in portable instrumentation. |
| VBATT-to-VOUT on-resistance ≤140Ω | Minimizes voltage drop during switchover, preserving >2.0V at RAM for reliable data retention. |
Applications
| Battery-Powered Portable Equipment | Embedded Controller Supervision |
|---|---|
|
Use Scenario: Handheld medical meters and data loggers operating on single-cell lithium batteries with intermittent USB charging. IC Role / Device Role / Timing Role: Monitors main 3.3V rail, asserts RESET during battery swap or low-VCC events, and seamlessly switches RAM to VBATT during power gaps. Use Value: Prevents firmware corruption and preserves sensor calibration memory across 10,000+ power cycles without external supervision logic. |
Use Scenario: Industrial PLC I/O modules requiring deterministic boot sequencing and watchdog-verified firmware execution. IC Role / Device Role / Timing Role: Generates clean, glitch-immune reset pulse at power-up; feeds WDI with periodic µP heartbeat; triggers hard reset on communication stall. Use Value: Eliminates need for discrete RC reset networks and external watchdog ICs, reducing BOM count by 3 components per module. |
| Intelligent Instrumentation | Critical µP Power Monitoring |
|
Use Scenario: Benchtop multimeters and oscilloscopes with nonvolatile configuration storage and real-time clock backup. IC Role / Device Role / Timing Role: Supplies regulated VOUT to SRAM and RTC; uses PFI to monitor 5V analog supply; asserts PFO as interrupt on analog rail failure. Use Value: Enables simultaneous monitoring of multiple rails with one IC, maintaining timestamp accuracy and user settings during AC dropout. |
Use Scenario: Telecom line cards where µP must remain operational during brief 48V DC input dips caused by relay switching. IC Role / Device Role / Timing Role: Detects sub-2.625V excursions on local 3.3V DC/DC output; holds RESET asserted for full 200ms even if dip lasts <10µs. Use Value: Provides immunity to fast transients while guaranteeing µP reset on sustained brownout, meeting GR-63-CORE reliability requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX804TCSA+ | 3.075V reset threshold (±2%), identical pinout and features | Suitable for 3.3V ±5% systems; asserts reset earlier than MAX804RCSA+ during gradual VCC decay | Select when system requires tighter margin above nominal 3.3V rail and brownout detection at 3.075V. |
| MAX804SCSA+ | 2.925V reset threshold (±2%), same SO-8 package and functionality | Optimized for 3.3V ±10% supplies; tolerates deeper droop before asserting reset vs. MAX804RCSA+ | Choose for legacy 3.3V designs with wider tolerance or where longer brownout hold-off is needed. |
Compared with MAX804RCSA+, MAX804TCSA+ offers earlier reset assertion for tighter 3.3V regulation, while MAX804SCSA+ delays reset to accommodate looser supply specs-enabling precise brownout response tuning without PCB changes.
Availability
MAX804RCSA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, intelligent instruments, critical µP power monitoring, and portable equipment requiring stable component supply and long-term industrial lifecycle support.
Supply support for MAX804RCSA+ 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 and reliability-critical functions.
The MAX804RCSA+ belongs to Maxim's 3.0V/3.3V microprocessor supervisory family, engineered specifically for robust power-up/down sequencing, battery-backed memory retention, and watchdog-secured operation in space-constrained embedded systems.
FAQ
What is the exact reset threshold voltage for MAX804RCSA+?
The MAX804RCSA+ has a nominal reset threshold of 2.625V, with ±2% tolerance over temperature and supply variations. This value is guaranteed to assert reset before VCC falls below 2.59V and not assert prematurely above 2.70V, making it ideal for 3.0V ±10% systems where brownout detection must occur after 2.7V but before 2.59V.
Does MAX804RCSA+ support active-high or active-low reset output?
MAX804RCSA+ provides an active-high, open-drain RESET output (pin 7), which differs from the active-low RESET found on MAX690/MAX704 variants. It requires an external pull-up resistor to VCC and asserts logic high during reset conditions-including VCC < 2.625V, watchdog timeout, or manual reset assertion-ensuring compatibility with µPs expecting high-active reset signaling.
Can MAX804RCSA+ operate without a backup battery?
Yes, MAX804RCSA+ can operate without a backup battery: connect both VBATT (pin 8) and VOUT (pin 1) to VCC (pin 2). In this configuration, the battery switchover function is disabled, but all other supervision features-including reset generation, watchdog, and PFI/PFO monitoring-remain fully functional for systems without RAM backup requirements.
What is the maximum load current supported by the VOUT pin of MAX804RCSA+?
The VOUT pin of MAX804RCSA+ delivers up to 50mA with a worst-case voltage drop of VCC – 0.15V, and up to 100mA with guaranteed short-circuit protection disabled. For CMOS RAM backup, typical loads are <5mA; exceeding 50mA risks thermal shutdown or degraded regulation, so external buffering is recommended for higher-current applications.
How does the watchdog timer in MAX804RCSA+ interact with the reset function?
The watchdog timer in MAX804RCSA+ triggers a reset pulse if WDI (pin 6) remains static for ≥1.6 seconds. The timer clears on any WDI edge transition and stays cleared while RESET is asserted. Unlike some variants, the watchdog cannot be disabled-ensuring continuous fault detection. When triggered, it forces the active-high RESET output high for 200ms, identical to power-on reset timing.
MAX804RCSA+ 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:
- -
MAX804RCSA+ FAQ
1.How can I place an order for MAX804RCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX804RCSA+ 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 MAX804RCSA+ reliable?
The price and inventory of MAX804RCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX804RCSA+ is usually 5 days.
3.What payment methods are accepted for MAX804RCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX804RCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX804RCSA+?
MAX804RCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX804RCSA+ 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 MAX804RCSA+?
For technical support, including MAX804RCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX804RCSA+ requirements.
6.How does Aetrix verify that MAX804RCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX804RCSA+ 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 MAX804RCSA+ meets industry standards.
7.What is the process for return or replacement of MAX804RCSA+?
All MAX804RCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX804RCSA+, 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 MAX804RCSA+ part is unused and in its original packaging.
Return procedure for MAX804RCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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