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Analog Devices Inc./Maxim Integrated MAX690SEPA+
- Part No.:
- MAX690SEPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX690SEPA+.pdf
- Description:
- IC SUPERVISOR MPU 8-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,738
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Product details
Overview
MAX690SEPA+ 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-enabling reliable CMOS RAM retention in portable controllers.
For engineers reviewing the MAX690SEPA+ datasheet, MAX690SEPA+ pinout, MAX690SEPA+ application, or MAX690SEPA+ equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, ±4% reset threshold accuracy, 40µA VCC supply current, and compatibility with lithium backup batteries exceeding VCC voltage.
Technical Context
The MAX690SEPA+ integrates a precision reset comparator with 10mV hysteresis, a non-disableable 1.6s watchdog timer cleared by WDI edges, and a dual-path power switch: a 3Ω PMOS connects VCC to VOUT during normal operation, while a 140Ω switch engages VBATT-to-VOUT when VCC drops below VSW (2.40V) and VBATT > VCC.
Its PFI input monitors external supplies against a 1.237V reference with ±20mV hysteresis; PFO asserts low on power-fail or VCC undervoltage. The MR input features a 70µA internal pull-up and holds RESET low for 200ms after release-supporting manual reset without external debounce.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.925V (nominal), ±4% tolerance - ensures reset assertion before VCC falls below 2.85V in 3.3V±10% systems |
| Reset Timeout Period | 200ms (typical) - guarantees minimum reset pulse width for µP initialization stability |
| Watchdog Timeout | 1.6s - detects µP lockup if WDI lacks transitions; timer clears on rising/falling edge |
| VCC Supply Current | 40µA (typ, VCC < 3.6V) - enables ultra-low-power operation in battery-backed embedded systems |
| Battery Supply Current | 1µA (max) - minimizes drain on lithium backup cells during extended standby |
| VBATT-to-VOUT On-Resistance | 140Ω (typ) - limits voltage drop during battery switchover to preserve RAM data integrity |
| Operating Temperature | -40°C to +85°C - qualified for industrial-grade embedded controller environments |
Pinout & Package
MAX690SEPA+ is housed in an 8-pin plastic DIP (PDIP) package with through-hole mounting and RoHS-compliant lead-free finish (+ suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω switch); must connect to RAM VDD |
| 2 - VCC | Main system supply input | Accepts 3.0V–5.5V; powers internal circuitry and enables VCC-to-VOUT path above reset threshold |
| 3 - GND | Ground reference | Common return for all analog/digital functions; requires local 0.1µF decoupling |
| 4 - PFI | Power-fail input | Monitors external supply via resistor divider; triggers PFO low when voltage falls below 1.237V |
| 5 - PFO | Power-fail open-drain output | Signals undervoltage condition; can be tied to MR on compatible parts to generate reset |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets watchdog timer; cannot be disabled |
| 7 - RESET | Active-low reset output | Asserts low during power-up, brownout, watchdog timeout, or MR activation; guaranteed to VCC = 1V |
| 8 - VBATT | Backup battery input | Accepts up to 6.0V; enables automatic switchover to preserve RAM when VCC fails |
Key Features
| Feature | Design Value |
|---|---|
| Battery-backup switchover | Automatic VBATT engagement at VCC = 2.40V with 140Ω switch - preserves CMOS RAM without external FETs |
| Guaranteed reset to 1V | RESET remains valid down to VCC = 1V - ensures robust reset assertion during deep brownouts |
| Integrated watchdog timer | 1.6s timeout with edge-triggered clear - eliminates need for external timing components |
| Precision reset comparator | ±4% threshold accuracy and 10mV hysteresis - prevents chatter during slow VCC ramps |
| Low quiescent current | 40µA VCC supply current - extends battery life in portable equipment with continuous monitoring |
Applications
| Portable Medical Monitor | Industrial PLC Controller |
|---|---|
Use Scenario: Battery-powered handheld ECG device requiring RAM data retention during AC power loss or battery swap. IC Role / Device Role / Timing Role: Supervisory IC providing VCC brownout detection, automatic VBATT switchover, and 200ms reset pulse for µP recovery. Use Value: Prevents data corruption in SRAM during transient power gaps using 2.40V switchover threshold and 1µA battery leakage. |
Use Scenario: DIN-rail mounted programmable logic controller operating in harsh factory environments with fluctuating 3.3V rails. IC Role / Device Role / Timing Role: Power-monitoring IC asserting RESET on undervoltage, enabling watchdog supervision of firmware execution. Use Value: Ensures deterministic µP restart under brownout conditions with ±4% reset accuracy and -40°C to +85°C operation. |
| Smart Energy Meter | Embedded Point-of-Sale Terminal |
Use Scenario: Utility meter with real-time clock and flash memory needing tamper-proof power-fail logging. IC Role / Device Role / Timing Role: Dual-function supervisor generating PFO interrupt on main supply sag and asserting RESET on critical undervoltage. Use Value: Enables accurate timestamped event capture via PFI/PFO interface while maintaining secure reset behavior. |
Use Scenario: Compact retail terminal using lithium coin cell for RTC and configuration backup during mains failure. IC Role / Device Role / Timing Role: System health monitor providing manual reset (MR), watchdog supervision (WDI), and battery-backed RAM supply (VOUT). Use Value: Supports hot-swap battery replacement without triggering reset due to VCC > VSW holdoff during switchover. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690TEPA+ | Higher reset threshold (3.075V) and same 200ms timeout; identical pinout and package | Better suited for 3.3V ±5% systems where tighter supply tolerance is required | Select MAX690TEPA+ when system VCC regulation is tighter and brownout margin must exceed 3.0V |
| MAX704SESA+ | SO-8 package (surface-mount), same 2.925V threshold, but adds active-high RESET output option | Enables PCB space savings and automated assembly; RESET output differs in polarity and drive strength | Choose MAX704SESA+ for new SMT designs requiring footprint reduction and compatibility with active-high reset µPs |
Compared with MAX690SEPA+, MAX690TEPA+ raises the reset threshold for stricter 3.3V supply systems, while MAX704SESA+ offers surface-mount packaging and active-high reset flexibility-neither is pin-compatible without layout revision, and both require validation of reset polarity and load drive capability.
Availability
MAX690SEPA+ is available at Aetrix Electronics and suitable for battery-powered computers, embedded controllers, intelligent instruments, and critical µP power monitoring requiring stable component supply across industrial temperature ranges.
Supply support for MAX690SEPA+ 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, computing, and communications markets.
The MAX690 family targets 3.0V/3.3V microprocessor systems requiring integrated power supervision, battery switchover, and watchdog functionality in compact DIP/SO packages.
FAQ
What is the reset threshold voltage for MAX690SEPA+?
The MAX690SEPA+ has a nominal reset threshold voltage of 2.925V, with ±4% tolerance over temperature. This value is specified for VCC falling conditions and ensures reset assertion before VCC drops below 2.85V in 3.3V±10% systems. The threshold is factory-trimmed and does not require external calibration. MAX690SEPA+ maintains this specification across its full -40°C to +85°C operating range.
Does MAX690SEPA+ support battery backup with voltages higher than VCC?
Yes, MAX690SEPA+ supports VBATT voltages exceeding VCC-such as 3.6V lithium cells-without damage or malfunction. Its battery switchover circuit engages when VCC falls below 2.40V (VSW) and VBATT > VCC, connecting VBATT to VOUT through a 140Ω switch. This design allows safe operation with backup sources up to 6.0V, as confirmed in the Absolute Maximum Ratings table for MAX690SEPA+.
Can the watchdog timer in MAX690SEPA+ be disabled?
No, the watchdog timer in MAX690SEPA+ cannot be disabled. It is a fixed-function 1.6s timeout circuit that triggers RESET if the WDI pin remains static (high or low) for longer than the timeout period. The timer clears only on rising or falling edges at WDI or during active RESET assertion. This behavior is explicitly documented in the Watchdog Input section of the MAX690SEPA+ datasheet and applies to all MAX690T/S/R variants.
What is the function of the PFI and PFO pins on MAX690SEPA+?
On MAX690SEPA+, the PFI (Power-Fail Input) pin monitors an external voltage-typically via a resistor divider-against a 1.237V internal reference. When PFI falls below this threshold, the PFO (Power-Fail Output) pin goes low as an open-drain signal. PFO can be used to trigger interrupts or, when connected to MR on compatible parts like MAX704, initiate a system reset. Both functions operate independently of the main reset comparator.
Is MAX690SEPA+ compatible with manual reset push-button interfaces?
Yes, MAX690SEPA+ supports direct connection of a momentary push-button to the MR (Manual Reset) pin. The device includes a 70µA internal pull-up, so the button pulls MR to GND when pressed. RESET remains asserted for 200ms after release, eliminating the need for external debounce circuitry. This behavior is guaranteed across the full -40°C to +85°C temperature range and is validated in the Electrical Characteristics table for MAX690SEPA+.
MAX690SEPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX690SEPA+ FAQ
1.How can I place an order for MAX690SEPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690SEPA+ 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 MAX690SEPA+ reliable?
The price and inventory of MAX690SEPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690SEPA+ is usually 5 days.
3.What payment methods are accepted for MAX690SEPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690SEPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690SEPA+?
MAX690SEPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690SEPA+ 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 MAX690SEPA+?
For technical support, including MAX690SEPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690SEPA+ requirements.
6.How does Aetrix verify that MAX690SEPA+ is sourced from the original manufacturer or authorized distributors?
All MAX690SEPA+ 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 MAX690SEPA+ meets industry standards.
7.What is the process for return or replacement of MAX690SEPA+?
All MAX690SEPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX690SEPA+, 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 MAX690SEPA+ part is unused and in its original packaging.
Return procedure for MAX690SEPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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