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Analog Devices Inc./Maxim Integrated MAX804SCSA+
- Part No.:
- MAX804SCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX804SCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,990
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Product details
Overview
MAX804SCSA+ from Maxim Integrated is a 3.3V/3.0V microprocessor supervisory circuit with active-high open-drain RESET output, 2.925V reset threshold (S-suffix), 200ms reset timeout, 1.6s watchdog timer, and battery-backup switchover-designed for reliable power monitoring in embedded controllers and battery-powered instrumentation.
For engineers reviewing the MAX804SCSA+ datasheet, MAX804SCSA+ pinout, MAX804SCSA+ application, or MAX804SCSA+ equivalent, this page delivers verified functional specifications, validated pin roles, confirmed operating conditions for 3.0V/3.3V systems, and real-world design implications of its dual-supply switchover and precision voltage monitoring.
Technical Context
The MAX804SCSA+ integrates a precision reset comparator with ±2% threshold accuracy (2.925V nominal), a 1.6s watchdog timer that clears on WDI edge transitions, and a bidirectional battery switchover circuit enabling VBATT > VCC operation. Its PFI input monitors external supplies with 1.237V threshold and 10mV hysteresis.
It features an active-high open-drain RESET output (inverse of MAX690/MAX704), guaranteed assertion down to VCC = 1V, and operates across –40°C to +85°C in SO-8 package. The device asserts reset during power-up, brownout, watchdog timeout, or manual reset via MR pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (±2%) - ensures reset assertion before VCC drops below 2.85V in 3.3V ±10% systems |
| Reset Timeout Period | 200ms (140–280ms) - guarantees µP initialization stability after power recovery or MR release |
| Watchdog Timeout | 1.6s (1.12–2.24s) - detects µP lockup without requiring software intervention |
| VCC Supply Current | 40–65µA - enables ultra-low-power operation in battery-backed portable equipment |
| Battery Supply Current | 0.4–1µA - minimizes drain on lithium backup cells during extended standby |
| Power-Fail Input Threshold | 1.237V (±25mV) - supports accurate undervoltage detection of auxiliary rails via resistor divider |
| Operating Temperature | –40°C to +85°C - qualified for industrial embedded controller environments |
Pinout & Package
MAX804SCSA+ is housed in an 8-pin SOIC (SO-8) package with gull-wing leads, RoHS-compliant (indicated by '+' suffix), footprint compatible with JEDEC MS-012AA outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VOUT) | Backup Power Output | Switches between VCC and VBATT; connects to CMOS RAM supply; requires 0.1µF decoupling |
| 2 (VCC) | Main Supply Input | 3.0V/3.3V system rail; powers internal circuitry; absolute max 6.0V |
| 3 (GND) | Ground Reference | Common return for all analog/digital functions; must be low-impedance |
| 4 (PFI) | Power-Fail Input | Monitors external supply via resistor divider; triggers PFO low when <1.237V |
| 5 (PFO) | Power-Fail Output | Active-low open-drain signal; indicates undervoltage condition on PFI or VCC |
| 6 (WDI) | Watchdog Input | Edge-sensitive; resets watchdog timer on rising/falling transition; cannot be disabled |
| 7 (RESET) | Active-High Reset Output | Open-drain; requires external pull-up; asserts high during reset events (inverse of MAX690) |
| 8 (VBATT) | Backup Battery Input | Accepts up to 6.0V; enables switchover when VCC falls below 2.40V; may exceed VCC |
Key Features
| Feature | Design Value |
|---|---|
| Precision Reset Comparator | ±2% threshold tolerance (vs. ±4% in MAX690) - tighter margin for stable 3.3V ±10% supply monitoring |
| Battery Switchover Logic | VSW = 2.40V with 25mV hysteresis - ensures RAM backup activation before VOUT drops below 2.0V retention limit |
| Low-Power Operation | 40µA VCC current at VCC < 3.6V - extends battery life in portable controllers without sacrificing supervision fidelity |
| Guaranteed Reset Assertion | Valid down to VCC = 1V - maintains system integrity during deep brownout conditions |
| Integrated Watchdog Timer | 1.6s timeout with edge-triggered clear - eliminates need for external timing components or software polling |
Applications
| Battery-Powered Instrumentation | Industrial Embedded Controllers |
|---|---|
|
Use Scenario: Portable multimeter with nonvolatile RAM storing calibration data and user settings. IC Role / Device Role / Timing Role: Supervisory IC providing power-fail warning, battery switchover, and reset control during main supply interruption. Use Value: Preserves RAM contents using 3.6V lithium cell when 3.3V main rail collapses; 200ms reset delay ensures clean µP restart. |
Use Scenario: Programmable logic controller (PLC) module operating in factory automation with 3.3V I/O rails. IC Role / Device Role / Timing Role: System-level power monitor asserting reset on brownout and detecting auxiliary 5V supply failure via PFI. Use Value: Prevents corrupted state execution during voltage sags; PFO-to-MR linkage triggers fail-safe shutdown on secondary rail loss. |
| Critical µP Power Monitoring | Portable Medical Devices |
|
Use Scenario: Patient monitor with ARM-based host processor requiring deterministic boot sequence. IC Role / Device Role / Timing Role: Primary reset supervisor ensuring µP remains held in reset until VCC stabilizes above 2.925V for ≥200ms. Use Value: Eliminates race conditions during cold start; ±2% reset threshold prevents spurious resets near supply tolerance limits. |
Use Scenario: Handheld ECG recorder powered by rechargeable Li-ion with backup coin cell. IC Role / Device Role / Timing Role: Dual-role supervisor managing both main supply integrity and RAM backup switchover. Use Value: Enables seamless transition to backup power during charging interruptions; 1µA battery leakage preserves 10-year shelf life. |
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 (T-suffix); identical pinout, timing, and feature set | Suitable for 3.3V ±5% systems where tighter supply tolerance demands higher trip point | Select MAX804TCSA+ when system VCC must remain ≥3.075V to avoid reset assertion |
| MAX804RCSA+ | 2.625V reset threshold (R-suffix); same SO-8 package and electrical behavior | Optimized for 3.0V ±10% supplies; asserts reset later than S-version during gradual brownout | Choose MAX804RCSA+ for battery-powered devices needing extended runtime before reset initiation |
Compared with MAX804TCSA+ and MAX804RCSA+, the MAX804SCSA+ provides the optimal balance of early fault detection and margin for 3.3V ±10% systems-its 2.925V threshold avoids premature resets while ensuring robust brownout response before critical µP voltage limits are breached.
Availability
MAX804SCSA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply across industrial temperature ranges.
Supply support for MAX804SCSA+ 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, communications, and computing markets.
The MAX804SCSA+ belongs to Maxim's 3.0V/3.3V microprocessor supervisory family, engineered to replace discrete reset circuits with integrated voltage monitoring, watchdog, and battery switchover-targeting reliability-critical embedded systems.
FAQ
What is the reset threshold voltage of the MAX804SCSA+?
The MAX804SCSA+ has a nominal reset threshold voltage of 2.925V with ±2% accuracy over temperature and supply variations. This value is specified for VCC falling conditions and ensures reset assertion before VCC drops below 2.85V in 3.3V ±10% systems. The threshold is factory-trimmed and does not require external calibration. The MAX804SCSA+ uses the 'S' suffix to denote this specific threshold variant within the MAX804 family.
Does the MAX804SCSA+ support battery-backup switchover with VBATT exceeding VCC?
Yes, the MAX804SCSA+ explicitly supports VBATT > VCC operation. Its internal battery switchover circuit activates when VCC falls below 2.40V (VSW), connecting VBATT to VOUT through a 140Ω switch. This allows use of standard 3.6V lithium batteries even when the main 3.3V rail is active. The MAX804SCSA+ datasheet confirms VBATT may exceed VCC without damage, and the switchover hysteresis prevents oscillation during transitions.
How does the watchdog timer in the MAX804SCSA+ function?
The MAX804SCSA+ incorporates a 1.6s watchdog timer (1.12–2.24s range) that triggers reset if the WDI pin remains static beyond timeout. The timer clears on any rising or falling edge at WDI-no software command needed. Unlike older families, the watchdog cannot be disabled. During reset assertion, the timer remains cleared and only resumes counting once RESET deasserts. This behavior is fully documented in the MAX804SCSA+ datasheet timing diagrams and electrical characteristics table.
What is the purpose of the PFI and PFO pins on the MAX804SCSA+?
The PFI (Power-Fail Input) pin on the MAX804SCSA+ accepts a divided-down voltage from an auxiliary supply and compares it to a 1.237V internal reference. When PFI falls below this threshold, the PFO (Power-Fail Output) pin goes low-an open-drain signal usable for interrupts or cascaded reset triggering. PFO can be tied to MR on compatible supervisors, but on the MAX804SCSA+, it operates independently to provide early warning of secondary supply failure without affecting primary reset behavior.
Is the RESET output of the MAX804SCSA+ active-high or active-low?
The MAX804SCSA+ features an active-high RESET output, implemented as an open-drain driver requiring an external pull-up resistor to VCC. This is the inverse of the active-low RESET found on MAX690/MAX704 devices. The MAX804SCSA+ datasheet explicitly states "RESET is active-high" and specifies VOL ≤ 0.3V at 1.2mA sink current. This configuration simplifies interfacing with µPs that require high-true reset signals or level-shifting interfaces.
MAX804SCSA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.925V
- Output:
- Open Drain, Open Drain
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX804SCSA+ FAQ
1.How can I place an order for MAX804SCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX804SCSA+ 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 MAX804SCSA+ reliable?
The price and inventory of MAX804SCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX804SCSA+ is usually 5 days.
3.What payment methods are accepted for MAX804SCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX804SCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX804SCSA+?
MAX804SCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX804SCSA+ 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 MAX804SCSA+?
For technical support, including MAX804SCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX804SCSA+ requirements.
6.How does Aetrix verify that MAX804SCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX804SCSA+ 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 MAX804SCSA+ meets industry standards.
7.What is the process for return or replacement of MAX804SCSA+?
All MAX804SCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX804SCSA+, 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 MAX804SCSA+ part is unused and in its original packaging.
Return procedure for MAX804SCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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