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Analog Devices Inc./Maxim Integrated MAX802LCSA+
- Part No.:
- MAX802LCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX802LCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,118
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Product details
Overview
The MAX802LCSA+ from Maxim Integrated is a microprocessor supervisory circuit providing precision reset generation, battery-backup switchover, watchdog timer, and power-fail detection for +5V systems. It asserts an active-low RESET pulse during power-up (VCC ≥ 1V), brownout (VCC < 4.65V), and watchdog timeout (1.6s), while switching VOUT to VBATT when VCC drops below threshold-enabling reliable CMOS RAM retention in battery-powered controllers.
For engineers reviewing the MAX802LCSA+ datasheet, MAX802LCSA+ pinout, MAX802LCSA+ application, or MAX802LCSA+ equivalent, key selection criteria include its guaranteed 4.65V reset threshold with ±2% power-fail accuracy, 200ms reset pulse width, 200μA quiescent supply current, and 50nA battery-backup mode current-critical for low-power embedded systems requiring deterministic reset behavior and long-term data retention.
Technical Context
The MAX802LCSA+ integrates four independent functional blocks: a precision bandgap-based reset generator with hysteresis (40mV), a 1.6s watchdog timer cleared by WDI edges or reset assertion, a 1.25V reference comparator for PFI/PFO power-fail signaling, and a dual-path PMOS switchover circuit (5Ω VCC path, 80Ω VBATT path) with 40mV hysteresis to prevent oscillation during slow VCC decay.
Its reset output remains asserted until VCC rises 200ms above 4.65V, and it guarantees RESET low down to VCC = 1V. The device operates over 1.0V to 5.5V VCC, supports battery voltages up to 4.80V, and disables the power-fail comparator when VBATT powers VOUT to conserve backup energy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V nominal, ±2% accuracy at +25°C-ensures consistent brownout detection across temperature and supply variation in +5V systems. |
| Reset Pulse Width | 200ms minimum-guarantees sufficient duration to fully initialize microprocessors like Intel 80C51 or Motorola 68HC11. |
| Watchdog Timeout | 1.6s nominal-provides robust software hang detection without excessive false triggers in real-time control loops. |
| Quiescent Current | 200μA typical at VCC = 5V-minimizes standby power draw in always-on monitoring applications. |
| Battery-Backup Current | 50nA typical at VCC = 0V, VBATT = 2.8V-enables multi-year lithium battery life for static RAM backup. |
| Power-Fail Comparator Ref | 1.25V internal reference-allows precise undervoltage detection of unregulated supplies via external resistor divider. |
| VOUT Switch Resistance | 5Ω (VCC path), 80Ω (VBATT path)-limits voltage drop under load while maintaining fast switchover response. |
Pinout & Package
MAX802LCSA+ is housed in an 8-pin SOIC package (3.9mm × 4.9mm, 1.27mm pitch) with gull-wing leads, RoHS-compliant and lead-free (indicated by '+' suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 5Ω PMOS) and VBATT (via 80Ω PMOS) based on reset threshold crossing-maintains RAM voltage during brownout. |
| 2 - VCC | +5V main supply input | Primary power source; powers internal circuitry and enables VOUT connection to VCC when above 4.65V. |
| 3 - GND | Ground reference | Common return for all analog and digital functions; must be low-impedance for accurate reset threshold and PFI sensing. |
| 4 - PFI | Power-fail comparator input | Monitors divided-down supply voltage; asserts PFO low when input falls below 1.25V-signals impending power loss. |
| 5 - PFO | Power-fail output | Open-drain active-low signal used to trigger μP interrupt or initiate graceful shutdown before VCC collapse. |
| 6 - WDI | Watchdog timer input | Edge-sensitive input; toggling within 1.6s prevents reset; floating or static state disables watchdog-supports fail-safe firmware supervision. |
| 7 - RESET | Active-low reset output | Push-pull output asserted low during power-up, brownout, or watchdog timeout; guaranteed valid down to VCC = 1V. |
| 8 - VBATT | Backup battery input | Provides alternate power to VOUT when VCC fails; accepts 2.8V–4.80V lithium cells; diode-isolated from substrate to prevent leakage. |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset threshold | 4.65V with ±2% power-fail accuracy-enables reliable system-level brownout response without external calibration. |
| Guaranteed reset assertion | Valid down to VCC = 1V-ensures microprocessor remains held in reset even during deep undervoltage conditions. |
| Low-power battery-backup mode | 50nA quiescent current-extends lithium battery life to >10 years for static RAM retention in infrequently powered systems. |
| Integrated switchover hysteresis | 40mV built-in hysteresis-prevents chattering during slow VCC ramp-down, eliminating need for external RC networks. |
| Watchdog timer disable via WDI float | Internal 35% VCC bias on WDI-allows hardware-enforced watchdog disable without pull-up/down resistors. |
Applications
| Industrial Data Loggers | Battery-Powered Medical Devices |
|---|---|
Use Scenario: Continuous environmental sensor data acquisition with periodic flash storage writes, operating on primary battery with optional supercapacitor backup. IC Role / Device Role / Timing Role: Supervisory IC providing brownout-triggered reset, RAM backup switchover, and watchdog supervision of data logging firmware. Use Value: Prevents corrupted flash writes during power interruption and preserves volatile buffer contents using 50nA backup current-enabling reliable field-deployed operation. | Use Scenario: Portable glucose monitor with real-time display, Bluetooth LE transmission, and nonvolatile configuration storage. IC Role / Device Role / Timing Role: Reset generator and power-fail detector ensuring safe shutdown before battery depletion, plus RAM retention for last-measurement cache. Use Value: 4.65V reset threshold aligns with LiMnO₂ cell discharge curve; 200ms reset pulse guarantees full MCU initialization prior to measurement cycle restart. |
| Smart Utility Meters | Embedded Point-of-Sale Terminals |
Use Scenario: AMI electricity meter with tamper detection, time-of-use billing, and secure firmware updates-subject to grid voltage sags and surges. IC Role / Device Role / Timing Role: System supervisor asserting RESET during AC line brownouts and enabling backup power to SRAM holding encryption keys and metering registers. Use Value: ±2% power-fail accuracy ensures consistent detection across temperature; 80Ω VBATT switch resistance limits voltage sag under 250μA load-preserving cryptographic integrity. | Use Scenario: Retail terminal with EFTPOS interface, thermal receipt printer, and persistent transaction queue stored in CMOS RAM. IC Role / Device Role / Timing Role: Dual-role supervisor: generating clean reset on power application and switching RAM to backup during AC outage or battery swap. Use Value: Guaranteed RESET assertion to VCC = 1V prevents partial initialization; 40mV switchover hysteresis eliminates flicker during marginal AC input-ensuring transaction atomicity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX805LCSA+ | Active-high RESET output (RESET); identical 4.65V threshold, 200ms pulse, and 1.6s watchdog-same pinout and functionality except reset polarity. | Required for μPs with active-high reset inputs (e.g., Intel 80C51); not interchangeable without board-level logic inversion. | Select MAX805LCSA+ only when target microprocessor mandates active-high reset assertion. |
| MAX706PESA+ | Lower 2.63V reset threshold; no battery switchover or PFI/PFO comparator; includes manual reset input and watchdog-but lacks VOUT switching capability. | Suitable for 3.3V systems or secondary voltage monitoring; cannot replace MAX802LCSA+ in battery-backed RAM applications. | Choose MAX706PESA+ for cost-sensitive 3.3V designs without backup power requirements-requires redesign of power management circuitry. |
Compared with MAX805LCSA+, the MAX802LCSA+ provides active-low reset compatibility with most legacy 8-bit μPs and integrated battery switchover, while MAX706PESA+ offers lower-voltage supervision but omits critical RAM backup functionality-making MAX802LCSA+ irreplaceable in applications requiring seamless VCC-to-VBATT transition.
Availability
MAX802LCSA+ is available at Aetrix Electronics and suitable for industrial data loggers, battery-powered medical devices, smart utility meters, and embedded point-of-sale terminals requiring stable component supply and long-term lifecycle support.
Supply support for MAX802LCSA+ 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, automotive, and communications markets.
The MAX802L family was designed specifically for microprocessor system supervision in battery-critical embedded applications-integrating reset, watchdog, power-fail detection, and seamless battery switchover in a single 8-pin SOIC.
FAQ
What is the guaranteed reset threshold voltage for MAX802LCSA+?
The MAX802LCSA+ has a guaranteed nominal reset threshold of 4.65V, with ±2% accuracy over temperature and supply variation as specified in the Electrical Characteristics table. This value applies to VCC falling conditions at +25°C and ensures deterministic brownout detection in +5V systems without external trimming.
Does MAX802LCSA+ support active-high reset output?
No, the MAX802LCSA+ provides only an active-low RESET output. For active-high reset functionality, the pin-compatible MAX805LCSA+ must be used-it is identical in all other specifications except reset polarity and includes the RESET output instead of RESET.
What is the maximum allowable backup battery voltage for MAX802LCSA+?
The MAX802LCSA+ supports a maximum backup battery voltage of 4.80V at VBATT, as documented in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1) when VCC is near the reset threshold, causing unwanted current flow and potential reliability issues.
How does the watchdog timer in MAX802LCSA+ get disabled?
The watchdog timer in MAX802LCSA+ is automatically disabled when the WDI pin is left floating-the internal 50kΩ pull-up biases WDI to ~35% of VCC, placing it in a non-logic state that clears the timer. Driving WDI continuously high or low also disables the watchdog, triggering a reset every ~1.8s (tWD + tRS).
Can MAX802LCSA+ operate with VCC below 4.65V and still assert RESET?
Yes, the MAX802LCSA+ guarantees RESET assertion down to VCC = 1V. As VCC drops below 4.65V, the internal reset generator holds RESET low; even if VCC continues falling to 1V, RESET remains asserted-ensuring the microprocessor stays in reset until power is fully removed or restored above threshold.
MAX802LCSA+ 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:
- 4.65V
- 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
MAX802LCSA+ FAQ
1.How can I place an order for MAX802LCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX802LCSA+ 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 MAX802LCSA+ reliable?
The price and inventory of MAX802LCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX802LCSA+ is usually 5 days.
3.What payment methods are accepted for MAX802LCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX802LCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX802LCSA+?
MAX802LCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX802LCSA+ 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 MAX802LCSA+?
For technical support, including MAX802LCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX802LCSA+ requirements.
6.How does Aetrix verify that MAX802LCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX802LCSA+ 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 MAX802LCSA+ meets industry standards.
7.What is the process for return or replacement of MAX802LCSA+?
All MAX802LCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX802LCSA+, 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 MAX802LCSA+ part is unused and in its original packaging.
Return procedure for MAX802LCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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