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Analog Devices Inc./Maxim Integrated MAX690SCSA+T
- Part No.:
- MAX690SCSA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690SCSA+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,834
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Product details
Overview
MAX690SCSA+T from Maxim Integrated is a 3.3V microprocessor supervisory circuit with active-low RESET output, 2.925V reset threshold, 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 embedded controllers requiring reliable power sequencing and RAM backup.
For engineers reviewing the MAX690SCSA+T datasheet, MAX690SCSA+T pinout, MAX690SCSA+T application, or MAX690SCSA+T equivalent, this page delivers verified specifications, validated pin functions, confirmed operating conditions (0°C to +70°C), and real-world substitution guidance for 3.0V/3.3V µP systems with battery backup.
Technical Context
The MAX690SCSA+T integrates a precision reset comparator with ±4% threshold tolerance, a 1.6s watchdog timer that clears on WDI edge transitions, and a dual-path power switch: VCC-to-VOUT via 3Ω PMOS and VBATT-to-VOUT via 140Ω NMOS. Its PFI input accepts external voltage dividers for auxiliary supply monitoring, while PFO provides open-drain power-fail warning.
Reset assertion is guaranteed down to VCC = 1V (with VBATT > 1V), and the device supports manual reset via MR with internal 70µA pull-up. Battery leakage is limited to ≤1µA across temperature, and VOUT regulation maintains VCC − 0.15V at 50mA load - enabling direct CMOS RAM backup without external regulators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (VCC falling), ±4% tolerance - ensures reset triggers before 3.3V supply drops below 2.85V system minimum. |
| Reset Timeout Period | 200ms (typical) - guarantees µP remains held in reset long enough for stable clock and supply settling. |
| VCC Supply Current | 40µA (typ, VCC < 3.6V) - enables ultra-low-power operation in battery-backed portable systems. |
| VBATT Supply Current | 1µA (max, −40°C to +85°C) - minimizes battery drain during extended backup mode. |
| Watchdog Timeout | 1.6s - detects µP lockup without requiring software intervention or external timing components. |
| Battery Switchover Threshold | VSW = 2.40V - initiates VBATT-to-VOUT switching early enough to preserve CMOS RAM data (>2.0V). |
| PFO Input Threshold | 1.237V ±20mV - allows accurate monitoring of secondary supplies (e.g., 5V rail via resistor divider). |
Pinout & Package
MAX690SCSA+T is housed in an 8-pin SOIC package (SO) with gull-wing leads, RoHS-compliant (indicated by '+' suffix), and rated for 0°C to +70°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS); must be decoupled with 0.1µF capacitor. |
| 2 - VCC | Main supply input | Accepts 1.0V to 5.5V; powers internal circuitry and enables VOUT sourcing when above reset threshold. |
| 3 - GND | Ground reference | Common return for all analog and digital functions; requires low-impedance PCB connection. |
| 4 - PFI | Power-fail input | Compares external voltage to 1.237V reference; asserts PFO low when input falls below threshold. |
| 5 - PFO | Power-fail open-drain output | Signals undervoltage condition; can drive MR on MAX704/MAX806 to trigger system reset. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets 1.6s timer on transition; tied high/low causes periodic reset. |
| 7 - RESET | Active-low reset output | Open-drain, logic-low during reset assertion; requires external pull-up for µP interface compatibility. |
| 8 - VBATT | Backup battery input | Supports voltages exceeding VCC (e.g., 3.6V Li-cell); connects to VOUT when VCC drops below 2.40V. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout, critical for nonvolatile memory retention. |
| 200ms reset time delay | Meets µP power-on reset timing requirements without external RC network or timing IC. |
| Battery-backup switchover with 2.40V threshold | Prevents premature battery engagement, extending lithium cell life while ensuring RAM data integrity. |
| 40µA VCC supply current (typ) | Reduces standby power in always-on embedded systems, enabling multi-year battery operation. |
| 1.6s watchdog timer with edge-clearing | Eliminates need for external watchdog IC and simplifies firmware design - no disable function required. |
Applications
| Battery-Powered Embedded Controller | Critical µP Power Monitoring |
|---|---|
|
Use Scenario: Industrial sensor node powered by coin-cell battery with 3.3V µP and SRAM. IC Role / Device Role / Timing Role: Supervisory IC asserting RESET during cold-start and brownout, switching VOUT to VBATT at 2.40V to retain SRAM state. Use Value: Enables 10+ year battery life with <1µA backup current and eliminates external reset IC and power-switch MOSFET. |
Use Scenario: Medical diagnostic device requiring guaranteed boot integrity after AC power interruption. IC Role / Device Role / Timing Role: Monitors main 3.3V supply; asserts RESET within 200ms if VCC dips below 2.925V, preventing corrupted firmware execution. Use Value: Meets IEC 62304 safety requirements for power-fail response without software dependency. |
| Intelligent Instrumentation | Portable Data Logger |
|
Use Scenario: Handheld multimeter with EEPROM calibration storage and real-time clock. IC Role / Device Role / Timing Role: Provides PFO-driven interrupt on auxiliary 5V supply sag and generates RESET pulse on main supply collapse. Use Value: Allows deterministic save-to-EEPROM before power loss using PFI/PFO interface, avoiding data corruption. |
Use Scenario: GPS-enabled environmental logger operating on rechargeable Li-ion with intermittent solar charging. IC Role / Device Role / Timing Role: Uses WDI to detect µP hang during satellite acquisition; triggers hardware reset independent of firmware state. Use Value: Recovers from RF stack lockups without user intervention, maintaining continuous logging uptime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704SCSA+ | Same 2.925V reset threshold, identical pinout, but adds manual reset (MR) input with internal pull-up. | Required where operator-initiated reset is needed; MAX690SCSA+ lacks MR functionality. | Select MAX704SCSA+ only if manual reset capability is mandatory - otherwise MAX690SCSA+ offers lower cost and same core supervision. |
| MAX802SCSA+ | Tighter reset threshold tolerance (±2% vs. ±4%) and improved PFI accuracy (±2% vs. ±4%). | Suitable for high-precision 3.3V systems where supply margin is <5%; not required for standard industrial designs. | Choose MAX802SCSA+ only when system-level voltage tolerance demands sub-2% reset accuracy - MAX690SCSA+ suffices for most 3.3V µP platforms. |
Compared with MAX704SCSA+, MAX690SCSA+ omits MR but reduces BOM count and cost; versus MAX802SCSA+, it trades tighter tolerances for broader compatibility and lower unit price - making MAX690SCSA+ optimal for cost-sensitive, battery-backed 3.3V embedded controllers.
Availability
MAX690SCSA+T is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, and intelligent instrumentation requiring stable component supply with guaranteed long-term availability.
Supply support for MAX690SCSA+T 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 connectivity in industrial, medical, and automotive systems.
The MAX690 family targets 3.0V/3.3V microprocessor systems needing integrated reset, watchdog, and battery-switchover functions - eliminating discrete solutions in space-constrained portable and embedded applications.
FAQ
What is the reset threshold voltage for MAX690SCSA+T?
The MAX690SCSA+T has a nominal reset threshold of 2.925V (VCC falling), with ±4% tolerance over temperature. This value is factory-trimmed and specified in the Electrical Characteristics table under VRST for MAX690S variants. The threshold ensures reset assertion before the 3.3V supply falls below 2.85V, aligning with typical system-level 10% supply tolerance requirements.
Does MAX690SCSA+T support manual reset functionality?
No, MAX690SCSA+T does not include a manual reset (MR) input. Unlike the MAX704SCSA+ or MAX806SCSA+, the MAX690SCSA+T pinout omits MR (pin 6 is WDI only). If manual reset is required, MAX704SCSA+ is the direct pin-compatible alternative with identical reset threshold and package.
How does the battery switchover work on MAX690SCSA+T?
MAX690SCSA+T switches VOUT from VCC to VBATT when VCC falls below 2.40V (VSW) and VBATT exceeds VCC. The internal 140Ω NMOS switch engages, preserving CMOS RAM power. Switchover back to VCC occurs only after VCC rises above the 2.925V reset threshold - ensuring stable supply re-engagement and avoiding oscillation near the switchover point.
What is the watchdog timeout period for MAX690SCSA+T?
The watchdog timeout period for MAX690SCSA+T is 1.6 seconds (typical), with a range of 1.12s to 2.24s over temperature and supply. The timer clears on any rising or falling edge at WDI (pin 6); tying WDI high or low results in periodic reset pulses every ~1.8s (tWD + tRS), as the timer restarts immediately after reset deassertion.
Can MAX690SCSA+T operate without a backup battery?
Yes, MAX690SCSA+T can operate without a backup battery: connect both VBATT (pin 8) and VOUT (pin 1) to VCC (pin 2). However, battery-switchover and RAM backup functions are disabled. For pure reset/watchdog applications without backup, consider the MAX706SCSA+ - a cost-optimized variant lacking VBATT/VOUT pins entirely.
MAX690SCSA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.925V
- 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
MAX690SCSA+T FAQ
1.How can I place an order for MAX690SCSA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690SCSA+T 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 MAX690SCSA+T reliable?
The price and inventory of MAX690SCSA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690SCSA+T is usually 5 days.
3.What payment methods are accepted for MAX690SCSA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690SCSA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690SCSA+T?
MAX690SCSA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690SCSA+T 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 MAX690SCSA+T?
For technical support, including MAX690SCSA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690SCSA+T requirements.
6.How does Aetrix verify that MAX690SCSA+T is sourced from the original manufacturer or authorized distributors?
All MAX690SCSA+T 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 MAX690SCSA+T meets industry standards.
7.What is the process for return or replacement of MAX690SCSA+T?
All MAX690SCSA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX690SCSA+T, 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 MAX690SCSA+T part is unused and in its original packaging.
Return procedure for MAX690SCSA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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