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Analog Devices Inc./Maxim Integrated MAX817LCSA+
- Part No.:
- MAX817LCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX817LCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,512
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Product details
Overview
The MAX817LCSA+ from Maxim Integrated is a +5V microprocessor supervisory circuit designed for precision supply monitoring, battery backup switchover, and active-low reset generation in embedded µP systems. It features a 4.65V ±5% reset threshold, 200ms reset timeout, 11µA quiescent current, and operates across 0°C to +70°C in an 8-pin SO package. It is used in portable equipment requiring reliable brownout protection and RAM backup during power failure.
For engineers reviewing the MAX817LCSA+ datasheet, MAX817LCSA+ pinout, MAX817LCSA+ application, or MAX817LCSA+ equivalent, this device delivers verified reset supervision, battery-freshness seal enablement, power-fail warning capability (via PFI/PFO), and transient-immune VCC monitoring - all critical for battery-powered controllers and intelligent instruments where deterministic reset timing and low-power integrity are mandatory.
Technical Context
The MAX817LCSA+ integrates a precision bandgap-based reset comparator with 25mV hysteresis, a 200ms internal reset timeout timer, and a battery switchover circuit that automatically connects BATT to OUT when VCC falls below both VRST (4.65V) and VBATT. Its PFI input monitors external voltages against a 1.25V reference, driving PFO low on undervoltage - enabling power-fail warnings independent of VCC status.
Unlike the MAX818/MAX819 variants, the MAX817LCSA+ lacks manual reset (MR) and chip-enable gating (CE IN/OUT), but retains watchdog input (WDI) with 1.6s timeout and battery freshness seal functionality activated via PFO latching. All logic outputs (RESET, PFO) are push-pull with rail-to-rail drive capability and sink/source current rated up to 3.2mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±5% - ensures reliable reset assertion before +5V supply drops into µP invalid operating range. |
| Reset Timeout Period | 200ms typical - guarantees minimum reset pulse width sufficient to initialize most 8/16-bit microcontrollers. |
| Supply Current | 11µA typical at +25°C - enables multi-year operation from coin-cell batteries in always-on monitoring applications. |
| VCC Operating Range | +4.75V to +5.5V - compatible with standard +5V regulated supplies and tolerant of nominal 5% line variation. |
| Battery Switchover Threshold | VCC < VBATT by ≥20mV - prevents oscillation during transition and ensures clean handover to backup power. |
| Power-Fail Input Threshold | 1.25V ±5mV - allows precise external voltage monitoring (e.g., 3.3V rail via resistor divider) without additional ICs. |
| Watchdog Timeout | 1.6s typical - provides robust software hang detection while minimizing false triggers from brief µP stalls. |
Pinout & Package
MAX817LCSA+ is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix). Pin 1 is marked with a beveled corner or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Supply output for CMOS RAM | Switches between VCC and BATT based on voltage comparison; drives RAM VDD during main/battery modes. |
| 2 VCC | Main +5V supply input | Primary power source; monitored for reset generation and used as reference for all internal comparators. |
| 3 GND | Ground reference | 0V return for all analog and digital functions; must be low-impedance connection to system ground plane. |
| 4 PFI | Power-fail comparator input | Accepts external voltage (e.g., via resistor divider); asserts PFO low when input falls below 1.25V threshold. |
| 5 PFO | Power-fail comparator output | Active-low open-drain/push-pull output; used for power-fail warning or battery freshness seal enablement. |
| 6 WDI | Watchdog timer input | Edge-sensitive input; reset triggered if no transition occurs within 1.6s; internally pulled low when unconnected. |
| 7 RESET | Active-low reset output | Pulsed low for ≥200ms on power-up, brownout, or watchdog timeout; sinks 3.2mA minimum at 0.4V. |
| 8 BATT | Backup battery input | Accepts 2.0V–6.0V battery or supercap; powers internal circuitry and OUT when VCC fails. |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset detection | 4.65V threshold with ±5% tolerance and 25mV hysteresis - eliminates false resets during noisy supply transients. |
| Battery freshness seal | Enables permanent battery isolation until first power cycle - preserves shelf life of backup cells in shipped products. |
| Low-quiescent-current operation | 11µA supply current - extends battery life in portable instrumentation and remote sensors. |
| Integrated power-fail comparator | Dedicated 1.25V reference with PFI/PFO pins - supports dual-rail monitoring (e.g., 3.3V or 2.5V) without external components. |
| Transient-immune VCC sensing | Designed to ignore fast transients ≤100µs at ≤100mV overdrive - improves reliability in electrically noisy environments. |
Applications
| Portable Data Loggers | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Battery-powered environmental sensor node logging temperature/humidity every 10 seconds with nonvolatile RAM retention. IC Role / Device Role / Timing Role: MAX817LCSA+ monitors main 5V supply and asserts RESET on brownout; switches RAM to BATT during outage; uses PFI to monitor Li-ion cell voltage. Use Value: Prevents data corruption during intermittent solar charging; ensures RAM contents survive >72h power loss with <1µA backup current. |
Use Scenario: DIN-rail mounted I/O module with isolated digital inputs, powered from 24VDC converted to +5V, requiring fail-safe state retention. IC Role / Device Role / Timing Role: MAX817LCSA+ provides supervised reset to ARM Cortex-M4 MCU and controls backup power path to SRAM holding configuration and last-valid I/O states. Use Value: Guarantees deterministic restart after AC dropout; maintains operational state across 500ms interruptions without EEPROM wear. |
| Medical Point-of-Care Devices | Smart Energy Meters |
|
Use Scenario: Handheld blood glucose meter with real-time clock, flash storage, and disposable battery pack. IC Role / Device Role / Timing Role: MAX817LCSA+ generates clean reset on battery insertion, enables battery freshness seal to preserve shelf life, and monitors backup capacitor health via PFI. Use Value: Eliminates need for factory programming of seal bits; ensures first-use battery voltage remains >2.8V after 24-month shelf life. |
Use Scenario: ANSI C12.20-compliant electricity meter with metrology SoC, RTC, and tamper-detection SRAM. IC Role / Device Role / Timing Role: MAX817LCSA+ supervises 5V metrology rail, triggers hardware reset on undervoltage, and gates power to RTC backup domain using BATT switchover. Use Value: Meets IEC 62053-21 requirement for 10-year RTC accuracy under brownout; reduces backup domain leakage to <1µA. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690ACSA+ | 4.65V reset threshold, 200ms timeout, but no PFI/PFO comparator or battery freshness seal; higher 25µA supply current. | Lacks power-fail warning and battery preservation features; suitable only for basic reset-only use cases. | Select MAX690ACSA+ only if PFI monitoring and seal functionality are unnecessary and legacy design reuse is required. |
| TPS3808G18DBVR | 1.8V fixed reset threshold (not 4.65V); adjustable delay (0–10s); 1.4µA IQ; no battery switchover or PFI input. | Designed for low-voltage µPs (1.8V/3.3V), not +5V systems; requires external MOSFET for battery backup. | Choose TPS3808G18DBVR only for new 1.8V designs needing ultra-low IQ; not a functional substitute for MAX817LCSA+ in +5V applications. |
Compared with MAX690ACSA+, the MAX817LCSA+ adds integrated power-fail detection and battery seal - critical for portable instrumentation. Versus TPS3808G18DBVR, it provides native +5V supervision, battery switchover, and lower system BOM cost despite higher IQ, making it optimal for legacy and new 5V µP platforms.
Availability
MAX817LCSA+ is available at Aetrix Electronics and suitable for portable equipment, industrial PLC modules, medical point-of-care devices, and smart energy meters requiring stable component supply with long-term lifecycle support.
Supply support for MAX817LCSA+ 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 MAX817LCSA+ belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust +5V system monitoring, battery-backed memory retention, and deterministic reset behavior in space-constrained portable and embedded applications.
FAQ
What is the reset threshold voltage of the MAX817LCSA+ and how tightly is it specified?
The MAX817LCSA+ has a nominal reset threshold of 4.65V with a guaranteed tolerance of ±5% over the full operating temperature range (0°C to +70°C). This means the actual trip point falls between 4.418V and 4.883V, ensuring reliable reset assertion before most +5V microprocessors enter undefined operation. The device also includes 25mV of built-in hysteresis to prevent chatter near the threshold. This specification is confirmed in the Electrical Characteristics table of the official MAX817 datasheet.
Does the MAX817LCSA+ support battery backup switchover, and what are the switching conditions?
Yes, the MAX817LCSA+ supports automatic battery backup switchover. It connects the BATT pin to the OUT pin when two conditions are met simultaneously: VCC falls below the reset threshold (4.65V) AND VCC drops below VBATT by at least 20mV. Once engaged, the internal PMOS switch isolates VCC and supplies OUT from the battery, drawing less than 1µA in deep backup mode. This behavior is documented in the "Backup-Battery Switchover" section and Table 1 of the MAX817LCSA+ datasheet.
Can the MAX817LCSA+ generate a power-fail warning signal, and how is it implemented?
Yes, the MAX817LCSA+ includes a dedicated power-fail comparator with PFI (input) and PFO (output) pins. When the voltage applied to PFI falls below the internal 1.25V reference, PFO is driven low - providing a clean, logic-compatible power-fail warning. This function operates independently of VCC status and remains active even during battery backup. The PFI input accepts DC voltages from 0V to VCC and supports resistor-divider scaling for monitoring 3.3V, 2.5V, or other rails. Details appear in the "Power-Fail Comparator" subsection of the datasheet.
How does the battery freshness seal work on the MAX817LCSA+, and what is its purpose?
The battery freshness seal on the MAX817LCSA+ disconnects the backup battery from internal circuitry and OUT until the device is first powered. To enable it: apply battery to BATT, ground PFO, bring VCC above 4.65V and hold until RESET deasserts, then cycle VCC down. Once sealed, leakage drops to <10nA at +25°C, preserving battery shelf life for years. This feature ensures end users receive fully charged backup power - critical for medical and industrial devices shipped with pre-installed batteries. The procedure is defined in the "Battery Freshness Seal" section of the datasheet.
Is the MAX817LCSA+ pin-compatible with other members of the MAX817/MAX818/MAX819 family?
No, the MAX817LCSA+ is not pin-compatible with MAX818 or MAX819 variants. While all share the same 8-pin SO package footprint and core pin assignments (VCC, GND, RESET, BATT, OUT, PFI, PFO, WDI), the MAX818 adds CE IN/CE OUT on pins 4/5 (replacing PFI/PFO), and the MAX819 adds MR on pin 6 (replacing WDI). Thus, substituting MAX817LCSA+ for MAX818CSA+ or MAX819CSA+ would cause functional misconnection. Always verify pin mapping per variant using the "Selector Guide" in the MAX817 datasheet.
MAX817LCSA+ 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:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- -
- 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
MAX817LCSA+ FAQ
1.How can I place an order for MAX817LCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX817LCSA+ 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 MAX817LCSA+ reliable?
The price and inventory of MAX817LCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX817LCSA+ is usually 5 days.
3.What payment methods are accepted for MAX817LCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX817LCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX817LCSA+?
MAX817LCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX817LCSA+ 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 MAX817LCSA+?
For technical support, including MAX817LCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX817LCSA+ requirements.
6.How does Aetrix verify that MAX817LCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX817LCSA+ 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 MAX817LCSA+ meets industry standards.
7.What is the process for return or replacement of MAX817LCSA+?
All MAX817LCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX817LCSA+, 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 MAX817LCSA+ part is unused and in its original packaging.
Return procedure for MAX817LCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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