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Analog Devices Inc./Maxim Integrated MAX802SCSA+
- Part No.:
- MAX802SCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX802SCSA+.pdf
- Description:
- IC SUPERVISOR MPU 8-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,956
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Product details
Overview
MAX802SCSA+ from Maxim Integrated is a 3.3V/3.0V microprocessor supervisory circuit with active-low RESET output, precision 2.925V reset threshold (±2% tolerance), 200ms reset timeout, watchdog timer (1.6s timeout), and battery-backup switchover functionality. It monitors VCC supply integrity, asserts reset during brownout or watchdog fault, and switches CMOS RAM to VBATT when VCC falls below 2.40V - used in embedded controllers requiring reliable power-up sequencing and nonvolatile memory retention.
For engineers reviewing the MAX802SCSA+ datasheet, MAX802SCSA+ pinout, MAX802SCSA+ application, or MAX802SCSA+ equivalent, key selection criteria include its guaranteed RESET assertion down to VCC = 1V, 40µA VCC supply current, ±2% reset threshold accuracy, battery-switching capability with VBATT > VCC support, and SO-8 package compatibility for space-constrained industrial control modules.
Technical Context
The MAX802SCSA+ integrates a precision reset comparator with 10mV hysteresis, a 1.6-second watchdog timer that clears on WDI edge transitions, and a dual-path power switch: VCC-to-VOUT via a 3Ω PMOS and VBATT-to-VOUT via a 140Ω switch activated when VCC < 2.40V. Its PFI input accepts external voltage monitoring with 1.237V threshold and 10mV hysteresis.
It operates across –40°C to +85°C, supports manual reset via MR (70µA internal pull-up), guarantees RESET low for VCC < 2.925V, and maintains VOUT regulation during switchover - all without short-circuit protection, requiring external 0.1µF decoupling on VCC and VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 2.925V (±2%) - ensures reset assertion before VCC drops below system's 3.3V ±10% supply tolerance limit |
| Reset Timeout Period | 200ms (140–280ms over temperature) - provides sufficient hold time for µP initialization after power stabilization |
| Watchdog Timeout | 1.6s (1.12–2.24s over temperature) - detects µP lockup while allowing normal software servicing intervals |
| VCC Supply Current | 40–50µA at VCC < 3.6V - enables ultra-low-power operation in battery-backed portable systems |
| Battery Supply Current | 0.4–1µA - minimizes drain on lithium backup cells during extended standby |
| VBATT Switch Threshold | 2.40V (2.30–2.50V) - initiates switchover prior to CMOS RAM data retention failure (<2.0V) |
| PFO Threshold Accuracy | ±2% - delivers precise power-fail warning for auxiliary supply monitoring |
Pinout & Package
MAX802SCSA+ is housed in an 8-pin SOIC (SO-8) package with standard 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix), and moisture sensitivity level (MSL) 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω switch); must be decoupled with 0.1µF capacitor |
| 2 - VCC | Main supply input | Accepts 2.72V–5.5V; powers internal circuitry and sources VOUT when active; requires 0.1µF local bypass |
| 3 - GND | Ground reference | Common return for VCC, VBATT, and logic signals; substrate tied to higher of VCC/VBATT |
| 4 - PFI | Power-fail input | Monitors external supply via resistor divider; trips PFO low when voltage falls below 1.237V (±2%) |
| 5 - PFO | Power-fail output | Open-drain active-low signal indicating PFI undervoltage or VCC < 2.40V; can drive MR on compatible parts |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets watchdog timer; cannot be disabled; 0.3×VCC/0.7×VCC thresholds |
| 7 - RESET | Active-low reset output | Push-pull, not open-drain; asserts low for 200ms after VCC rise, MR release, or watchdog timeout |
| 8 - VBATT | Backup-battery input | Accepts up to 6.0V; may exceed VCC; connects to VOUT during switchover; requires 0.1µF bypass |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures deterministic reset behavior even during deep brownout, critical for fail-safe embedded recovery |
| ±2% reset and PFI threshold accuracy | Enables tighter system-level voltage margining than ±4% alternatives, reducing false resets in noisy environments |
| Battery switchover with VBATT > VCC support | Allows use of standard 3.6V lithium coin cells without level-shifting, simplifying backup power design |
| 200ms reset timeout with restart-on-brownout | Prevents premature µP release during transient dips; timer reinitializes each time VCC crosses threshold |
| 1.6s watchdog with automatic clear on WDI edge | Eliminates need for dedicated timer peripherals; robust against stuck-at-high/low faults |
| 40µA VCC quiescent current | Extends battery life in always-on portable instrumentation where supervisory current dominates standby load |
Applications
| Battery-Powered Embedded Controller | Industrial Data Logger with Nonvolatile RAM |
|---|---|
Use Scenario: A field-deployed environmental sensor node powered by AA batteries and backed by a 3.6V lithium cell maintains real-time clock and configuration data in CMOS RAM during main supply interruption. IC Role / Device Role / Timing Role: MAX802SCSA+ monitors VCC, asserts RESET during brownout, and seamlessly switches VOUT to VBATT to preserve RAM contents without software intervention. Use Value: Enables >10-year battery life with zero data loss during grid outages or battery replacement, leveraging 0.4–1µA VBATT current and 2.40V switchover threshold. |
Use Scenario: An industrial PLC module logs process variables to static RAM during mains failure, requiring guaranteed memory retention until backup power engages. IC Role / Device Role / Timing Role: MAX802SCSA+ acts as power-integrity guardian: triggers watchdog reset if firmware hangs, asserts RESET on VCC dip, and activates VBATT path before VOUT falls below 2.0V. Use Value: Achieves IEC 61508 SIL-2 compliance for safety-critical logging via deterministic 200ms reset timing and ±2% threshold accuracy. |
| Portable Medical Diagnostic Device | Smart Energy Meter with Tamper Detection |
Use Scenario: A handheld ultrasound device uses a rechargeable Li-ion pack and retains calibration coefficients and last-scan metadata in battery-backed RAM during shutdown cycles. IC Role / Device Role / Timing Role: MAX802SCSA+ provides power-on reset sequencing, monitors main rail for undervoltage, and enables manual reset via front-panel button (MR pin). Use Value: Guarantees RESET assertion down to VCC = 1V, ensuring safe boot even with degraded battery voltage, while 40µA supply current extends operational runtime. |
Use Scenario: A utility meter detects unauthorized enclosure opening using a magnetic switch feeding PFI, triggering immediate data save and secure shutdown via PFO-driven interrupt. IC Role / Device Role / Timing Role: MAX802SCSA+ repurposes PFI/PFO as tamper-sensing interface: PFI monitors switch state; PFO pulls MR low to force controlled reset and EEPROM commit. Use Value: Leverages existing supervisor resources instead of adding discrete comparators, reducing BOM count and PCB area while maintaining ±2% trip-point accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802TCSA+ | Higher reset threshold (3.075V ±2%) - suited for 3.3V ±5% supplies | Less tolerant of 3.3V system brownout; requires tighter VCC regulation | Select when system VCC nominal is 3.3V with <5% tolerance and no 3.0V operation required |
| MAX802RCSA+ | Lower reset threshold (2.625V ±2%) - optimized for 3.0V ±10% supplies | Asserts reset later during VCC decay; risks RAM data loss if VCC dips near 2.7V | Choose only for 3.0V systems where extended hold-up time outweighs reduced noise margin |
Compared with MAX802TCSA+ and MAX802RCSA+, the MAX802SCSA+ offers optimal balance for 3.3V systems with ±10% tolerance - its 2.925V threshold prevents premature reset during nominal ripple while guaranteeing action before CMOS RAM retention fails, making it the default choice for general-purpose 3.3V µP supervision.
Availability
MAX802SCSA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, and intelligent instruments requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX802SCSA+ 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 high-performance analog and mixed-signal ICs for industrial, communications, computing, and consumer applications.
The MAX802 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for reliable power-monitoring, reset generation, and battery-backup switching in 3.0V/3.3V embedded systems with stringent uptime requirements.
FAQ
What is the guaranteed operating temperature range for MAX802SCSA+?
The MAX802SCSA+ is rated for operation from –40°C to +85°C. This extended industrial temperature range ensures reliable performance in harsh environments such as factory automation equipment, outdoor telemetry units, and automotive under-hood modules. The device's reset threshold, watchdog timeout, and supply current specifications are fully characterized across this range, with minimal drift - for example, reset timeout varies only from 140ms to 280ms over temperature.
Does MAX802SCSA+ support battery voltage higher than VCC?
Yes, MAX802SCSA+ explicitly supports VBATT exceeding VCC - a core design feature enabling direct connection of standard 3.6V lithium coin cells without external regulators or diodes. The internal battery switchover circuit activates when VCC falls below 2.40V (2.30–2.50V), connecting VBATT to VOUT through a 140Ω switch. This architecture preserves RAM data even when main supply collapses, and is validated for VBATT up to 6.0V per absolute maximum ratings.
How does the watchdog timer in MAX802SCSA+ behave during reset assertion?
During RESET assertion (i.e., when RESET is low), the MAX802SCSA+ watchdog timer remains cleared and inactive - it does not count down. The timer only begins timing after RESET deasserts (goes high), and resets upon any rising or falling edge at WDI. This prevents spurious timeouts during boot or recovery sequences. If WDI is held static (high or low), a reset pulse occurs every ~1.8 seconds (tWD + tRS), ensuring fail-safe response even if firmware fails to service WDI.
Can MAX802SCSA+ be used without a backup battery?
Yes, MAX802SCSA+ can operate without a backup battery: connect both VBATT and VOUT pins directly to VCC. However, doing so disables battery switchover and power-fail detection (PFI/PFO remain functional). For pure reset supervision without backup features, alternatives like MAX706SCSA+ may offer lower cost and simpler biasing - but MAX802SCSA+ retains full reset, watchdog, and manual reset functionality regardless of VBATT connection status.
What is the function of the PFI and PFO pins on MAX802SCSA+?
PFI (Pin 4) is a precision 1.237V comparator input used to monitor auxiliary power rails or external signals; when voltage at PFI falls below this threshold, PFO (Pin 5) goes low. PFO is an open-drain output that can drive interrupts, trigger MR on compatible supervisors (e.g., MAX704), or interface with µP GPIOs. Its ±2% accuracy and 10mV hysteresis make it suitable for reliable power-fail detection - for instance, monitoring a 5V auxiliary rail via a resistor divider while leaving main reset supervision unaffected.
MAX802SCSA+ 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:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX802SCSA+ FAQ
1.How can I place an order for MAX802SCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX802SCSA+ 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 MAX802SCSA+ reliable?
The price and inventory of MAX802SCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX802SCSA+ is usually 5 days.
3.What payment methods are accepted for MAX802SCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX802SCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX802SCSA+?
MAX802SCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX802SCSA+ 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 MAX802SCSA+?
For technical support, including MAX802SCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX802SCSA+ requirements.
6.How does Aetrix verify that MAX802SCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX802SCSA+ 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 MAX802SCSA+ meets industry standards.
7.What is the process for return or replacement of MAX802SCSA+?
All MAX802SCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX802SCSA+, 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 MAX802SCSA+ part is unused and in its original packaging.
Return procedure for MAX802SCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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