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Analog Devices Inc./Maxim Integrated MAX802MCSA+
- Part No.:
- MAX802MCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX802MCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
The MAX802MCSA+ from Maxim Integrated is a microprocessor supervisory circuit providing reset generation, battery-backup switching, watchdog timer, and power-fail detection for +5V systems. It asserts active-low RESET during power-up, brownout (VCC < 4.40V), and watchdog timeout (1.6s), delivers VOUT from VCC or VBATT with 40mV switchover hysteresis, and features a 1.25V PFI comparator with ±2% power-fail accuracy-used in battery-powered controllers and intelligent instruments requiring reliable μP supervision.
For engineers reviewing the MAX802MCSA+ datasheet, MAX802MCSA+ pinout, MAX802MCSA+ application, or MAX802MCSA+ equivalent, key selection criteria include its 4.40V reset threshold, 200ms reset pulse width, 200μA quiescent current, battery-switching behavior under VCC failure, and compatibility with CMOS RAM backup in industrial embedded systems.
Technical Context
The MAX802MCSA+ integrates four independent supervisory functions: a precision voltage monitor with 4.40V reset threshold (±2% over temperature), a 1.6s watchdog timer cleared by WDI edges or RESET assertion, a 1.25V reference-based power-fail comparator driving open-drain PFO, and a dual-source power switch routing VCC or VBATT to VOUT based on voltage comparison with 40mV hysteresis.
Its internal architecture includes a P-channel MOSFET for VOUT switching (5Ω on-resistance when VCC-powered), a dedicated reset generator with guaranteed assertion down to VCC = 1V, and input protection allowing PFI/WDI operation beyond rail limits when current-limited to <10mA-enabling robust interfacing in noisy or marginal supply environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V nominal, with ±2% accuracy over temperature-ensures deterministic reset initiation before +5V supply collapse. |
| Reset Pulse Width | 200ms typical-guarantees sufficient duration to fully initialize microprocessors with long boot sequences. |
| Watchdog Timeout | 1.6s nominal-provides fail-safe recovery window for firmware stuck in infinite loops or interrupt latency spikes. |
| Quiescent Current | 200μA at VCC = 5V-minimizes standby power draw in battery-critical applications like portable instrumentation. |
| Battery-Backup Current | 50nA typical at VCC = 0V, VBATT = 2.8V-preserves lithium cell life during extended power loss. |
| VOUT Switch Resistance | 5Ω (VCC-to-VOUT), 80Ω (VBATT-to-VOUT)-limits voltage drop across switch to <25mV at 5mA load, maintaining RAM retention. |
| Power-Fail Comparator Accuracy | ±2% at TA = +25°C-enables precise early-warning detection of +5V regulator dropout using external resistor dividers. |
Pinout & Package
MAX802MCSA+ is housed in an 8-pin SOIC package (S8+2 outline, 1.98mm body width) with standard JEDEC SOIC-8 footprint and RoHS-compliant lead-free finish indicated by the '+' suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switched between VCC and VBATT; delivers regulated +5V or backup battery voltage to preserve memory during brownout. |
| 2 - VCC | Main +5V supply input | Primary power source; monitored for reset assertion and used as reference for all internal comparators. |
| 3 - GND | Analog/digital ground | Common return path for all internal circuits; must be low-impedance to ensure accurate voltage monitoring. |
| 4 - PFI | Power-fail comparator input | Accepts divided-down supply voltage; triggers PFO low when input falls below 1.25V reference. |
| 5 - PFO | Open-drain power-fail output | Active-low signal indicating impending supply failure; requires external pull-up for μP interrupt or latch control. |
| 6 - WDI | Watchdog timer input | Edge-sensitive input; toggling within 1.6s prevents reset; floating or static state disables watchdog function. |
| 7 - RESET | Active-low reset output | Push-pull output asserted low for 200ms during power-up, brownout, or watchdog timeout-directly drives μP reset pin. |
| 8 - VBATT | Backup battery input | Accepts 2.8V–4.55V lithium cell; enables automatic switchover to VOUT only when VCC < reset threshold and VBATT > VCC + 20mV. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures reliable reset hold-down even during severe undervoltage conditions where other supervisors may release prematurely. |
| 40mV battery switchover hysteresis | Prevents oscillatory switching between VCC and VBATT during slow VCC droop, eliminating RAM corruption risk. |
| 50nA battery-backup quiescent current | Extends shelf life of primary lithium cells beyond 10 years in storage, critical for maintenance-free field-deployed equipment. |
| ±2% power-fail accuracy | Enables accurate prediction of +5V regulator dropout point using simple resistor dividers-no calibration required. |
| Internal 1.25V reference for PFI | Provides stable trip point independent of VCC variation, allowing precise monitoring of auxiliary supplies or negative rails via external circuitry. |
Applications
| Battery-Powered Controllers | Intelligent Instruments |
|---|---|
Use Scenario: Portable data loggers powered by single 3.6V lithium cells operating in remote locations with intermittent AC charging. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, RAM backup switchover, and power-fail warning before main supply collapse. Use Value: Prevents data corruption during unexpected power loss and extends battery service life via 50nA backup-mode current. | Use Scenario: Handheld multimeters with nonvolatile memory storing calibration coefficients and user settings. IC Role / Device Role / Timing Role: Reset generator and battery switch ensuring SRAM retention during battery replacement or low-voltage events. Use Value: Enables hot-swap battery replacement without system reset or memory loss due to guaranteed VOUT continuity. |
| Critical μP Power Monitoring | Industrial PLC I/O Modules |
Use Scenario: Embedded controllers in factory automation systems where uncontrolled μP restart could cause process faults. IC Role / Device Role / Timing Role: Dual-function supervisor delivering both power-on reset and watchdog-triggered recovery for deterministic fault handling. Use Value: Eliminates need for discrete RC reset circuits and external watchdog timers-reducing BOM count and board area. | Use Scenario: DIN-rail mounted I/O modules with isolated +5V logic supplies and local battery-backed configuration storage. IC Role / Device Role / Timing Role: Voltage monitor and backup switch managing VOUT supply to EEPROM and real-time clock during mains failure. Use Value: Maintains configuration integrity and timekeeping accuracy during 100ms–500ms AC outage windows common in industrial power grids. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802LCSA+ | 4.60V reset threshold (vs. 4.40V); identical pinout, timing, and feature set | Suitable for +5V ±5% systems where higher reset threshold avoids nuisance resets during nominal supply ripple | Select MAX802LCSA+ when system VCC tolerance is tighter and brownout margin must exceed 100mV. |
| MAX706SCSA+ | 4.40V reset threshold, but lacks battery switchover and PFI/PFO functionality; adds manual reset input | Applicable where only reset supervision is needed and backup RAM is not required | Choose MAX706SCSA+ to reduce cost and complexity in designs without battery backup or power-fail warning needs. |
Compared with MAX802LCSA+, the MAX802MCSA+ provides lower reset threshold for earlier intervention in marginal +5V supplies; versus MAX706SCSA+, it adds integrated battery switching and power-fail detection-making it essential for systems requiring full supervisory coverage with memory retention.
Availability
MAX802MCSA+ is available at Aetrix Electronics and suitable for battery-powered controllers, intelligent instruments, and critical μP power monitoring requiring stable component supply across industrial temperature ranges and long-term production cycles.
Supply support for MAX802MCSA+ 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.
The MAX802MCSA+ belongs to Maxim's microprocessor supervisory product line, engineered specifically to replace discrete reset circuits and enhance reliability in +5V μP systems with battery backup and power-fail warning requirements.
FAQ
What is the guaranteed minimum VCC level at which MAX802MCSA+ asserts RESET?
The MAX802MCSA+ guarantees RESET assertion down to VCC = 1V across its full operating temperature range. This ensures the microprocessor remains held in reset during deep brownout conditions where other supervisors may release prematurely, preventing erratic execution. The device maintains this behavior regardless of VBATT voltage or watchdog state, making MAX802MCSA+ suitable for ultra-low-voltage recovery scenarios in safety-critical embedded systems.
How does the battery switchover hysteresis work in MAX802MCSA+?
The MAX802MCSA+ implements 40mV hysteresis between VCC and VBATT switchover thresholds: VBATT connects to VOUT when VCC falls below VBATT − 20mV, and VCC reconnects when it rises above VBATT + 20mV. This prevents oscillation during slow VCC droop, ensuring stable VOUT delivery to CMOS RAM. The hysteresis is fixed and internal-no external components are required-and applies only when VCC is below the 4.40V reset threshold, as confirmed in the MAX802MCSA+ datasheet timing diagrams and pin description table.
Can MAX802MCSA+ monitor a negative supply rail?
Yes, the MAX802MCSA+ can monitor a negative supply rail using its PFI input and internal 1.25V reference. By configuring an external resistor network (as shown in Figure 7 of the datasheet), the PFI node is biased such that PFO goes high when the negative rail degrades. The accuracy depends on resistor tolerances and PFI input current (≤25nA), but the core comparator functionality remains valid. This capability is explicitly documented for MAX802MCSA+ in the Applications Information section and does not require modification of the IC itself.
What is the maximum allowable VBATT voltage for MAX802MCSA+?
The maximum allowable VBATT voltage for MAX802MCSA+ is 4.55V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1) when VCC is near its reset threshold, causing unintended current flow from VBATT into the die. This limit applies specifically to the MAX802M variant (4.40V reset threshold) and differs from the 4.80V limit for MAX802L. Using a 3.6V lithium cell stays safely within this constraint.
Does MAX802MCSA+ support manual reset functionality?
No, the MAX802MCSA+ does not include a manual reset input. Its reset generation is fully automatic-triggered only by VCC brownout (<4.40V), watchdog timeout (1.6s), or power-up sequencing. Unlike related parts such as MAX706S or MAX800M, the MAX802MCSA+ pinout omits MR/MR̅ terminals, and the functional block diagram confirms no manual reset path. Designs requiring pushbutton-initiated reset must add external circuitry or select an alternative part with dedicated MR pin.
MAX802MCSA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.4V
- 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
MAX802MCSA+ FAQ
1.How can I place an order for MAX802MCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX802MCSA+ 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 MAX802MCSA+ reliable?
The price and inventory of MAX802MCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX802MCSA+ is usually 5 days.
3.What payment methods are accepted for MAX802MCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX802MCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX802MCSA+?
MAX802MCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX802MCSA+ 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 MAX802MCSA+?
For technical support, including MAX802MCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX802MCSA+ requirements.
6.How does Aetrix verify that MAX802MCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX802MCSA+ 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 MAX802MCSA+ meets industry standards.
7.What is the process for return or replacement of MAX802MCSA+?
All MAX802MCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX802MCSA+, 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 MAX802MCSA+ part is unused and in its original packaging.
Return procedure for MAX802MCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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