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Analog Devices Inc./Maxim Integrated MAX802RESA+
- Part No.:
- MAX802RESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX802RESA+.pdf
- Description:
- IC SUPERVISOR MAX802 MPU
- Quantity:
- Payment:
- Shipping:
Inventory:299
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Product details
Overview
MAX802RESA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-low reset output, precision voltage monitoring, 200ms reset timeout, 1.6s watchdog timer, and battery-backup switchover. It monitors VCC for brownout conditions, asserts RESET below 2.625V (R-suffix threshold), supports manual reset via MR pin, and switches VOUT to VBATT when VCC falls below 2.40V. Used in embedded controllers requiring reliable power-up sequencing and RAM backup.
For engineers reviewing the MAX802RESA+ datasheet, MAX802RESA+ pinout, MAX802RESA+ application, or MAX802RESA+ equivalent, key selection criteria include reset threshold accuracy (±2%), battery-switch hysteresis (25mV typical), VCC supply current (40µA typ), guaranteed RESET assertion down to VCC = 1V, and SO-8 package compatibility with industrial temperature range (–40°C to +85°C).
Technical Context
The MAX802RESA+ integrates a precision reset comparator with 2.625V nominal falling threshold (±2% tolerance), a 200ms internal reset timeout timer, and a non-disableable 1.6s watchdog timer cleared by WDI transitions. Its battery switchover circuit uses a 140Ω VBATT-to-VOUT switch activated when VCC drops below 2.40V (VSW) and VBATT > VCC, ensuring CMOS RAM retention before VOUT falls below 2.0V.
It features an open-drain PFO output tied to a 1.237V power-fail comparator with 10mV hysteresis, independent of reset logic; a manual reset input (MR) with 70µA internal pull-up; and dual-supply operation supporting VCC as low as 1.1V and VBATT up to 6.0V. All logic inputs (WDI, MR, PFI) accept TTL/CMOS levels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold (VCC falling) | 2.59V to 2.70V - guarantees reset assertion before VCC drops below system's 3.0V ±10% supply minimum |
| Reset Timeout Period | 140ms to 280ms - ensures µP remains held in reset long enough for stable power rail settling |
| Watchdog Timeout | 1.12s to 2.24s - detects µP lockup without requiring software intervention |
| VCC Supply Current | 40µA typical - enables ultra-low-power operation in battery-backed systems |
| Battery Supply Current | 0.4µA to 1µA - minimizes drain on lithium backup cells during extended standby |
| VBATT-to-VOUT On-Resistance | 140Ω typical - limits voltage drop during battery switchover to preserve RAM data integrity |
| Power-Fail Input Threshold | 1.212V to 1.262V - provides accurate undervoltage detection for auxiliary rails |
Pinout & Package
MAX802RESA+ is housed in an 8-pin SOIC (SO-8) package with standard 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix), and industrial-grade thermal performance (derate 5.88mW/°C above +70°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Supply output for CMOS RAM | Switches between VCC and VBATT; connects to VCC when VCC > VRST, to VBATT when VCC < VSW and VBATT > VCC |
| VCC (Pin 2) | Main supply input | Primary power source (1.1V to 5.5V); powers internal circuitry and defines reset threshold reference |
| GND (Pin 3) | Ground reference | Common return path for all analog and digital functions; substrate connected to higher of VCC/VBATT |
| PFI (Pin 4) | Power-fail input | Monitors external voltage divider; triggers PFO low when input falls below 1.237V ±20mV |
| PFO (Pin 5) | Power-fail output | Open-drain signal indicating undervoltage condition on PFI or VCC < VSW |
| WDI (Pin 6) | Watchdog input | Edge-sensitive input; clears 1.6s timer on rising/falling transition; cannot be disabled |
| RESET (Pin 7) | Active-low reset output | Push-pull output asserted low during power-up, brownout, or watchdog timeout; holds low ≥200ms |
| VBATT (Pin 8) | Backup-battery input | Accepts 3.6V lithium cell; may exceed VCC; enables seamless RAM backup during main supply failure |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures reliable reset hold during deep brownout, even when main supply collapses below 2.0V |
| 200ms reset timeout with restart-on-brownout | Prevents premature µP release during transient dips; timer resets each time VCC falls below threshold |
| Battery switchover at 2.40V (VSW) | Activates backup before VOUT drops below 2.0V RAM retention limit, extending data hold time |
| 1.237V PFI comparator with 10mV hysteresis | Provides noise-immune power-fail detection for secondary rails without external components |
| 40µA VCC supply current (typ) | Reduces quiescent load on primary supply, critical for long-life portable applications |
Applications
| Battery-Powered Embedded Controller | Critical µP Power Monitoring |
|---|---|
Use Scenario: Industrial sensor node powered by Li-ion battery with 3.3V LDO, requiring RAM retention during mains loss and brownout immunity during generator startup. IC Role / Device Role / Timing Role: Supervisory IC providing VCC monitoring, manual reset, watchdog supervision, and automatic VBATT switchover to VOUT for SRAM backup. Use Value: Guarantees RESET assertion down to VCC = 1V and switches to 3.6V battery at 2.40V, preserving firmware state for >72 hours on 100mAh cell. | Use Scenario: Medical infusion pump with safety-critical µP that must never execute corrupted code due to unstable 3.0V rail during battery swap. IC Role / Device Role / Timing Role: Precision reset supervisor asserting active-low RESET for ≥200ms after VCC exceeds 2.625V, with restart-on-brownout behavior. Use Value: ±2% reset threshold tolerance prevents spurious resets during 3.0V ±10% supply transients, meeting IEC 62304 Class C requirements. |
| Intelligent Instrument with Auxiliary Rail Monitoring | Portable Data Logger with SuperCap Backup |
Use Scenario: Handheld multimeter monitoring both 3.3V main rail and –5V analog rail, needing fault indication before µP executes calibration routines. IC Role / Device Role / Timing Role: Dual-role supervisor using PFI input to detect –5V rail collapse via resistor divider, driving PFO to trigger interrupt or assert MR. Use Value: 1.237V PFI threshold with 10mV hysteresis enables accurate –5V monitoring with <1% error, eliminating need for separate comparator. | Use Scenario: Environmental logger using 0.47F SuperCap charged from 5V USB port, requiring seamless transition to backup during field deployment. IC Role / Device Role / Timing Role: Battery switchover controller accepting VBATT > VCC, enabling direct SuperCap connection without diode drop or charge circuit. Use Value: VBATT-to-VOUT on-resistance of 140Ω allows >100mA backup current with <150mV drop, sustaining 3.3V logic for 45 minutes at 10mA load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802TESA+ | Higher reset threshold (3.075V ±2%) optimized for 3.3V ±5% supplies; identical pinout, timing, and feature set | Suitable for systems where brownout margin must align with tighter 3.3V tolerance bands | Select MAX802TESA+ when main supply regulation is ±5%; use MAX802RESA+ for ±10% 3.0V systems |
| MAX804RESA+ | Active-high open-drain RESET output (inverse logic), same reset threshold, watchdog, and switchover specs | Required for µPs with active-high reset inputs or level-sensitive reset latching circuits | Choose MAX804RESA+ only if host µP demands active-high reset assertion; otherwise MAX802RESA+ provides direct push-pull compatibility |
Compared with MAX802TESA+, MAX802RESA+ offers lower reset threshold for wider brownout coverage in 3.0V systems, while MAX804RESA+ provides logic-inverted reset signaling-neither is pin-compatible with MAX802RESA+ due to differing RESET output topology and drive type.
Availability
MAX802RESA+ is available at Aetrix Electronics and suitable for battery-powered computers, embedded controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply across industrial temperature ranges.
Supply support for MAX802RESA+ 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, mixed-signal, and power management ICs for industrial, automotive, and computing applications.
The MAX802 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust power monitoring and battery backup in 3.0V/3.3V embedded systems with stringent reliability requirements.
FAQ
What is the exact reset threshold voltage for MAX802RESA+?
The MAX802RESA+ has a nominal reset threshold of 2.625V for VCC falling, with a guaranteed range of 2.59V to 2.70V (±2% tolerance). This value is specified for the R-suffix variant and applies across the full industrial temperature range (–40°C to +85°C), ensuring consistent brownout detection in 3.0V ±10% systems.
Does MAX802RESA+ support battery backup with lithium cells exceeding VCC?
Yes, MAX802RESA+ explicitly supports VBATT > VCC operation. Its battery switchover circuit activates when VCC falls below 2.40V (VSW) and VBATT exceeds VCC, connecting VBATT to VOUT through a 140Ω internal switch. This allows direct use of 3.6V lithium coin cells without external diodes or regulators.
Can the watchdog timer in MAX802RESA+ be disabled?
No, the watchdog timer in MAX802RESA+ cannot be disabled. It is a fixed-function 1.6s timeout circuit (1.12s to 2.24s over temperature) that clears only on WDI transitions (rising or falling edges) or during RESET assertion. Tying WDI high or low will cause periodic resets every ~1.8s, making it unsuitable for applications requiring watchdog disable capability.
What is the function of the PFI and PFO pins on MAX802RESA+?
The PFI pin on MAX802RESA+ is a dedicated input for monitoring auxiliary power rails via a resistor divider, referenced to a precise 1.237V internal comparator. The PFO pin is an open-drain output that goes low when PFI falls below threshold or VCC drops below 2.40V, enabling power-fail interrupts or cascaded reset triggering without additional components.
Is MAX802RESA+ compatible with SO-8 PCB footprints used for MAX690 or MAX704 series?
Yes, MAX802RESA+ uses the same 8-pin SOIC (SO-8) package outline as MAX690 and MAX704 devices, with identical 1.27mm lead pitch and land pattern. However, pin functions differ: MAX802RESA+ has WDI on Pin 6 and RESET on Pin 7, whereas MAX690 places MR on Pin 6 and RESET on Pin 7-requiring schematic and layout verification before substitution.
MAX802RESA+ 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:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.625V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX802RESA+ FAQ
1.How can I place an order for MAX802RESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX802RESA+ 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 MAX802RESA+ reliable?
The price and inventory of MAX802RESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX802RESA+ is usually 5 days.
3.What payment methods are accepted for MAX802RESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX802RESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX802RESA+?
MAX802RESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX802RESA+ 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 MAX802RESA+?
For technical support, including MAX802RESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX802RESA+ requirements.
6.How does Aetrix verify that MAX802RESA+ is sourced from the original manufacturer or authorized distributors?
All MAX802RESA+ 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 MAX802RESA+ meets industry standards.
7.What is the process for return or replacement of MAX802RESA+?
All MAX802RESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX802RESA+, 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 MAX802RESA+ part is unused and in its original packaging.
Return procedure for MAX802RESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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