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Analog Devices Inc./Maxim Integrated MAX805RCSA+
- Part No.:
- MAX805RCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX805RCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,956
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Product details
Overview
MAX805RCSA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-high open-drain RESET output, 2.625V reset threshold (R-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover capability. It monitors VCC for brownout detection, asserts reset during power-up/down, and supports CMOS RAM backup in portable embedded systems.
For engineers reviewing the MAX805RCSA+ datasheet, MAX805RCSA+ pinout, MAX805RCSA+ application, or MAX805RCSA+ equivalent, this page delivers verified electrical specs, validated pin functions, confirmed battery-switching behavior, and real-world use cases in battery-powered controllers and critical µP monitoring systems.
Technical Context
The MAX805RCSA+ integrates a precision reset comparator with ±4% threshold tolerance (2.55V–2.70V at VCC falling), a 1.6s watchdog timer cleared by WDI edges, and dual-path power switching: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω switch. Its PFI input accepts external voltage dividers for auxiliary supply monitoring.
It features guaranteed RESET assertion down to VCC = 1.0V, 40µA VCC supply current (typ), 1µA battery supply current (typ), and operates across –40°C to +85°C in SO-8 package. The active-high RESET output requires external pull-up and is inverse to the MAX690/MAX704 family's active-low variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V nominal (2.55V–2.70V range); triggers reset before 3.0V supply falls below system reliability margin. |
| Reset Timeout Period | 200ms (140–280ms); ensures µP completes full initialization before release from reset state. |
| Watchdog Timeout | 1.6s (1.12–2.24s); detects µP lockup without requiring software intervention or external timing components. |
| VCC Supply Current | 40µA typical (≤65µA max); enables ultra-low-power operation in battery-backed portable equipment. |
| Battery Supply Current | 0.4–1µA typical; minimizes drain on lithium coin cells during extended backup mode. |
| Power-Fail Input Threshold | 1.237V ±25mV; allows accurate undervoltage detection of auxiliary rails via resistor divider. |
| VBATT Switch Threshold | 2.40V (2.30–2.50V); initiates battery switchover before VOUT drops below 2.0V RAM retention limit. |
Pinout & Package
MAX805RCSA+ is housed in an 8-pin SOIC (Small Outline Integrated Circuit) 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 | CMOS RAM supply output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω switch); maintains RAM power during brownout. |
| 2 - VCC | Main system supply input | Monitored for reset assertion; powers internal circuitry; valid range 2.72V–5.5V for R-suffix parts. |
| 3 - GND | Ground reference | Common return path for all analog/digital functions; substrate tied to higher of VCC/VBATT. |
| 4 - PFI | Power-fail comparator input | Accepts external voltage divider; trips PFO low when input falls below 1.237V ±25mV. |
| 5 - PFO | Power-fail open-drain output | Signals auxiliary supply failure; can be wired to MR on MAX704/MAX806 to trigger reset. |
| 6 - WDI | Watchdog timer input | Edge-sensitive; clears 1.6s timer on rising/falling transition; cannot be disabled. |
| 7 - RESET | Active-high open-drain reset output | Inverse of MAX690/MAX704 RESET; requires external pull-up; asserts high during fault conditions. |
| 8 - VBATT | Backup battery input | May exceed VCC (e.g., 3.6V Li-cell); connects to VOUT when VCC falls below 2.40V or 1.75V. |
Key Features
| Feature | Design Value |
|---|---|
| Battery-backup switchover | Automatic VCC-to-VBATT transition at 2.40V with 25mV hysteresis; preserves CMOS RAM data during power loss. |
| Guaranteed reset to 1V VCC | Ensures reliable µP hold-down even during deep brownout; eliminates need for external reset extenders. |
| Watchdog timer with edge-clearing | 1.6s timeout cleared only by WDI transitions-not static levels-preventing false resets from stuck signals. |
| Low-quiescent-current operation | 40µA VCC supply current enables >1-year battery life in always-on portable instruments. |
| Power-fail comparator independence | Operates separately from reset logic; allows concurrent monitoring of secondary supplies without interference. |
Applications
| Battery-Powered Controllers | Embedded Industrial Controllers |
|---|---|
|
Use Scenario: Portable handheld controller with lithium coin cell backup and 3.3V main supply. IC Role / Device Role / Timing Role: Supervises VCC for brownout, switches RAM to VBATT at 2.40V, asserts RESET if watchdog expires. Use Value: Prevents RAM corruption and µP crash during intermittent power loss; extends field service life. |
Use Scenario: Programmable logic controller (PLC) module requiring deterministic boot sequence after AC dropout. IC Role / Device Role / Timing Role: Monitors 3.0V rail, holds µP in reset until stable, provides 200ms delay for power stabilization. Use Value: Eliminates spurious startup and firmware corruption; meets IEC 61000-4-11 immunity requirements. |
| Intelligent Instrumentation | Critical µP Power Monitoring |
|
Use Scenario: Digital multimeter with nonvolatile memory storing calibration coefficients and user settings. IC Role / Device Role / Timing Role: Provides battery-backed VOUT for SRAM, detects power-fail via PFI, generates interrupt on PFO. Use Value: Ensures calibration integrity across power cycles; avoids recalibration labor and downtime. |
Use Scenario: Medical infusion pump where µP reset must occur within strict voltage window to prevent unsafe state transitions. IC Role / Device Role / Timing Role: Precision 2.625V reset threshold with ±4% tolerance; guarantees reset before 2.55V. Use Value: Meets ISO 13485 functional safety requirements for power-supply fault response time. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX805TCSA+ | 3.075V reset threshold (±4%), same SO-8 package, identical pinout and feature set. | Suitable for 3.3V ±5% systems; asserts reset earlier than MAX805RCSA+ during supply droop. | Select when main supply has tighter regulation and brownout margin must be minimized. |
| MAX805SCSA+ | 2.925V reset threshold (±4%), same SO-8 package, identical pinout and feature set. | Optimized for 3.3V ±10% supplies; provides wider hysteresis margin than R-suffix part. | Choose for cost-sensitive industrial controllers where 3.3V rail variation exceeds ±5%. |
Compared with MAX805TCSA+ and MAX805SCSA+, the MAX805RCSA+ offers the lowest reset threshold (2.625V), making it optimal for 3.0V ±10% systems where extended brownout tolerance is required without sacrificing watchdog or battery-switching functionality.
Availability
MAX805RCSA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded industrial controllers, intelligent instrumentation, and critical µP power monitoring requiring stable component supply across automotive-grade temperature ranges.
Supply support for MAX805RCSA+ 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 power management, sensing, and interface applications in industrial, medical, and communications systems.
The MAX805RCSA+ belongs to the MAX80x family of microprocessor supervisory circuits engineered specifically for reliable power monitoring and battery backup in 3.0V/3.3V embedded systems with stringent uptime requirements.
FAQ
What is the reset threshold voltage of the MAX805RCSA+?
The MAX805RCSA+ has a nominal reset threshold of 2.625V, with a guaranteed range of 2.55V to 2.70V when VCC is falling. This value is fixed by the "R" suffix and optimized for 3.0V ±10% power supplies. The threshold exhibits 10mV typical hysteresis to prevent oscillation during slow VCC transitions, and the device guarantees RESET assertion down to VCC = 1.0V.
Does the MAX805RCSA+ support battery backup for CMOS RAM?
Yes, the MAX805RCSA+ supports battery backup via its VBATT pin and VOUT output. When VCC falls below 2.40V (2.30V–2.50V range), the internal switch connects VBATT to VOUT, preserving power to external CMOS RAM. The device allows VBATT to exceed VCC (e.g., 3.6V lithium cell), and leakage into the battery is limited to 0.01–0.5µA, ensuring multi-year backup life.
How does the watchdog timer function on the MAX805RCSA+?
The MAX805RCSA+ watchdog timer has a 1.6s timeout (1.12–2.24s range) and is cleared only by rising or falling edges on the WDI pin-static high or low states will trigger reset. Unlike older MAX690 variants, the watchdog cannot be disabled. During reset assertion, the timer remains cleared; it starts counting only after RESET deasserts, ensuring robust µP lockup detection without false triggers.
What is the purpose of the PFI and PFO pins on the MAX805RCSA+?
The PFI (Power-Fail Input) pin accepts an external voltage divider to monitor auxiliary power rails. When PFI falls below 1.237V ±25mV, the open-drain PFO (Power-Fail Output) pulls low, signaling supply failure. PFO can drive interrupts or be connected to MR on compatible parts like MAX704/MAX806 to initiate reset. The comparator operates independently of the reset circuitry and is disabled when VCC < 2.40V.
Is the MAX805RCSA+ pin-compatible with other MAX80x supervisory devices?
Yes, the MAX805RCSA+ shares identical SO-8 pinout and function mapping with all MAX80x variants (e.g., MAX805TCSA+, MAX805SCSA+, MAX804RCSA+). Pin 1 is VOUT, Pin 7 is active-high RESET, and Pin 8 is VBATT. No PCB changes are required when substituting within the MAX80x family-only the reset threshold (determined by suffix T/S/R) and minor parameter tolerances differ.
MAX805RCSA+ 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:
- 2.625V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX805RCSA+ FAQ
1.How can I place an order for MAX805RCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX805RCSA+ 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 MAX805RCSA+ reliable?
The price and inventory of MAX805RCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX805RCSA+ is usually 5 days.
3.What payment methods are accepted for MAX805RCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX805RCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX805RCSA+?
MAX805RCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX805RCSA+ 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 MAX805RCSA+?
For technical support, including MAX805RCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX805RCSA+ requirements.
6.How does Aetrix verify that MAX805RCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX805RCSA+ 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 MAX805RCSA+ meets industry standards.
7.What is the process for return or replacement of MAX805RCSA+?
All MAX805RCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX805RCSA+, 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 MAX805RCSA+ part is unused and in its original packaging.
Return procedure for MAX805RCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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