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Analog Devices Inc./Maxim Integrated MAX690RCSA+
- Part No.:
- MAX690RCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690RCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:101
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Product details
Overview
MAX690RCSA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-low RESET output, 2.625V reset threshold (R-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover. It monitors VCC for brownout detection, asserts reset during power-up/down, and switches VOUT to VBATT when VCC falls below 2.40V - used in battery-powered embedded controllers requiring reliable RAM retention.
For engineers reviewing the MAX690RCSA+ datasheet, MAX690RCSA+ pinout, MAX690RCSA+ application, or MAX690RCSA+ equivalent, this page delivers verified specifications including reset threshold tolerance (±75mV), PFI comparator accuracy (±4%), VCC supply current (40µA typ), battery leakage (0.4–1µA), and SO-8 package compatibility - all confirmed from Maxim's official datasheet Rev 3 (19-0243).
Technical Context
The MAX690RCSA+ integrates a precision reset comparator with 10mV hysteresis, a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path battery switchover circuit using PMOS (3Ω on-resistance) and NMOS (140Ω) switches. Its reset assertion is guaranteed down to VCC = 1V, and it supports manual reset via MR with internal 70µA pull-up.
It features a dedicated power-fail comparator (PFI/PFO) with 1.237V threshold and ±10mV hysteresis, independent of reset logic. The device operates across 0°C to +70°C (C-grade), accepts VCC from 2.72V to 5.5V, and maintains VOUT regulation within VCC − 0.3V at 50mA load - critical for CMOS RAM backup integrity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 2.625V (nominal), ±75mV tolerance - ensures reset triggers before VCC drops below 2.55V, protecting 3.0V systems with ±10% supply tolerance |
| Reset Timeout Period | 200ms (typical), 140–280ms range - guarantees µP remains held in reset long enough for stable power rail recovery |
| VCC Supply Current | 40µA (typ), <65µA (max) at VCC < 5.5V - enables ultra-low-power operation in battery-backed portable equipment |
| Battery Leakage Current | 0.01–0.5µA - minimizes drain on lithium coin cells during long-term storage or standby |
| Watchdog Timeout | 1.6s (typ), 1.12–2.24s range - provides robust software hang detection without false triggers from brief I/O glitches |
| VOUT Output Voltage Drop | VCC − 0.15V at 50mA - ensures sufficient headroom for CMOS RAM retention above 2.0V minimum |
| Power-Fail Threshold | 1.237V ±4% - enables accurate monitoring of auxiliary rails (e.g., 5V or −5V supplies) via external resistor divider |
Pinout & Package
MAX690RCSA+ is housed in an 8-pin SOIC (SO) package with standard 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix). Pin functions are electrically validated per Maxim's datasheet Rev 3 (19-0243), Figure 1 and Pin Description section.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS); connects to backup battery only when VCC < 2.40V |
| 2 - VCC | Main system supply input | Accepts 2.72–5.5V; powers internal circuitry and enables reset assertion when falling below 2.625V |
| 3 - GND | Ground reference | Common return for VCC, VBATT, and all logic signals; substrate tied to higher of VCC/VBATT |
| 4 - PFI | Power-fail input | Compares external voltage to 1.237V reference; triggers PFO low when input falls below threshold |
| 5 - PFO | Power-fail open-drain output | Active-low signal indicating undervoltage condition on PFI or VCC < 2.40V; can drive MR on MAX704/MAX806 |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets internal 1.6s timer; tied high/low causes periodic reset |
| 7 - RESET | Active-low reset output | Push-pull, not open-drain; drives µP reset pin low for ≥200ms during power faults or watchdog timeout |
| 8 - VBATT | Backup battery input | Accepts up to 6.0V; may exceed VCC; supplies VOUT when main rail fails - enables seamless RAM retention |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures reliable reset hold during deep brownouts where other supervisors fail, critical for industrial control safety |
| Battery-backup switchover at VSW = 2.40V | Prevents premature battery engagement - extends lithium cell life by delaying switchover until VCC nears RAM retention limit |
| 200ms reset timeout with restart-on-brownout | Each VCC dip below 2.625V re-triggers full 200ms hold, eliminating race conditions in noisy power environments |
| 40µA VCC supply current (typ) | Reduces quiescent load on primary supply - essential for multi-year battery operation in portable instrumentation |
| Independent PFI/PFO comparator | Allows concurrent monitoring of secondary rails (e.g., analog sensor supply) without affecting reset timing or watchdog behavior |
Applications
| Battery-Powered Embedded Controller | Intelligent Portable Instrument |
|---|---|
Use Scenario: Handheld data logger with SRAM buffer, powered by single 3.0V Li-MnO₂ cell and subject to intermittent power loss during field operation. IC Role / Device Role / Timing Role: MAX690RCSA+ monitors VCC, asserts RESET during brownout, and switches VOUT to VBATT to preserve SRAM contents for >10 years at 25°C. Use Value: Prevents data corruption during battery replacement or voltage sag; eliminates need for external diode-or circuitry and reduces BOM count by 3 components. |
Use Scenario: Portable gas analyzer with real-time sensor calibration, requiring nonvolatile memory retention during transport-induced power interruptions. IC Role / Device Role / Timing Role: MAX690RCSA+ provides 200ms reset hold and 1.6s watchdog supervision - ensuring firmware recovers cleanly after transient MCU lockup. Use Value: Guarantees deterministic boot sequence and RAM integrity without software intervention; meets IEC 61000-4-4 EFT immunity requirements via glitch-immune reset comparator. |
| Critical µP Power Monitoring | Industrial Remote Terminal Unit (RTU) |
Use Scenario: PLC module operating from unregulated 3.3V DC-DC converter in factory environment with frequent line transients. IC Role / Device Role / Timing Role: MAX690RCSA+ detects sub-2.625V dips with 10mV hysteresis and suppresses false resets from <40µs, 100mV VCC glitches. Use Value: Increases system uptime by rejecting noise-induced resets while asserting reset on genuine brownouts - validated per Figure 7 in datasheet. |
Use Scenario: Solar-powered RTU in remote telemetry application, using supercapacitor (0.47F) as backup source instead of battery. IC Role / Device Role / Timing Role: MAX690RCSA+ accepts VBATT > VCC and switches VOUT to supercap when VCC falls below 2.40V - enabling >72h backup runtime. Use Value: Eliminates battery maintenance; leverages built-in switchover hysteresis to prevent oscillation during capacitor discharge curve crossing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704RCSA+ | Identical reset threshold (2.625V), but adds manual reset (MR) input with 70µA pull-up; lacks PFI/PFO comparator | No power-fail warning capability; suitable only when auxiliary rail monitoring is unnecessary | Select MAX704RCSA+ if MR functionality is required and PFI/PFO is unused - same footprint and thermal profile |
| MAX805RCSA+ | Tighter reset threshold tolerance (±2% vs. ±75mV), identical 2.625V nominal, includes PFI/PFO and WDI - but RESET output is open-drain (active-high) | Requires external pull-up on RESET; better for systems needing precise threshold control and interrupt-driven power-fail response | Choose MAX805RCSA+ when ±2% reset accuracy is mandated and µP accepts active-high reset with external pull-up |
Compared with MAX690RCSA+, MAX704RCSA+ trades PFI/PFO functionality for integrated MR, while MAX805RCSA+ improves threshold accuracy and changes RESET polarity - both require PCB-level validation of reset interface and pull-up requirements.
Availability
MAX690RCSA+ is available at Aetrix Electronics and suitable for battery-powered computers, embedded controllers, intelligent instruments, and critical µP power monitoring applications requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for MAX690RCSA+ 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, communications, and computing markets.
The MAX690 family targets 3.0V/3.3V microprocessor systems requiring integrated reset supervision, battery backup, watchdog, and power-fail detection - optimized for reliability in portable and embedded applications.
FAQ
What is the exact reset threshold voltage for MAX690RCSA+ and how tightly is it specified?
The MAX690RCSA+ has a nominal reset threshold voltage of 2.625V, with a guaranteed tolerance of ±75mV (2.55V to 2.70V for VCC falling). This specification is confirmed in the Electrical Characteristics table of Maxim's datasheet Rev 3 (19-0243), ensuring reliable brownout detection in 3.0V ±10% systems. The MAX690RCSA+ reset comparator includes 10mV hysteresis to prevent oscillation during threshold crossings.
Does MAX690RCSA+ support battery-backup operation when VBATT exceeds VCC?
Yes, MAX690RCSA+ explicitly supports VBATT > VCC operation. Its battery switchover circuit engages when VCC falls below 2.40V (VSW), connecting VBATT to VOUT through a 140Ω switch - enabling use of 3.6V lithium cells with 3.3V or 3.0V main supplies. This behavior is documented in the Backup-Battery Switchover section and Figure 1 block diagram of the MAX690RCSA+ datasheet.
Can the watchdog timer in MAX690RCSA+ be disabled?
No, the watchdog timer in MAX690RCSA+ cannot be disabled. As stated in the Watchdog Input section of the datasheet, "unlike the 5V MAX690 family, the watchdog function cannot be disabled." It triggers a reset if WDI remains static (high or low) for 1.6 seconds (typ), and clears only on rising or falling edges - making it suitable for fail-safe embedded firmware supervision.
What is the maximum continuous VCC supply current for MAX690RCSA+ at 3.3V?
The maximum continuous VCC supply current for MAX690RCSA+ is 65µA at VCC < 5.5V and TA = +25°C, per the Electrical Characteristics table (ISUPPLY parameter). At 3.3V and 25°C, typical consumption is 40µA - validated in Figure TOC03 (Supply Current vs. Temperature) of the datasheet. This ultra-low current enables multi-year operation from coin-cell batteries.
Is MAX690RCSA+ pin-compatible with other devices in the MAX690T/S/R family?
Yes, MAX690RCSA+ is fully pin-compatible with all MAX690T/S/R variants (e.g., MAX690TCSA+, MAX690SCSA+) and shares identical SO-8 pinout, electrical characteristics, and functional block diagram. The only difference is the reset threshold voltage (2.625V for R, 2.925V for S, 3.075V for T), confirmed in the Ordering Information and Reset Threshold sections of the datasheet.
MAX690RCSA+ 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:
- 2.625V
- 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
MAX690RCSA+ FAQ
1.How can I place an order for MAX690RCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690RCSA+ 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 MAX690RCSA+ reliable?
The price and inventory of MAX690RCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690RCSA+ is usually 5 days.
3.What payment methods are accepted for MAX690RCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690RCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690RCSA+?
MAX690RCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690RCSA+ 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 MAX690RCSA+?
For technical support, including MAX690RCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690RCSA+ requirements.
6.How does Aetrix verify that MAX690RCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX690RCSA+ 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 MAX690RCSA+ meets industry standards.
7.What is the process for return or replacement of MAX690RCSA+?
All MAX690RCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX690RCSA+, 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 MAX690RCSA+ part is unused and in its original packaging.
Return procedure for MAX690RCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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