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Analog Devices Inc./Maxim Integrated MAX690REPA+
- Part No.:
- MAX690REPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX690REPA+.pdf
- Description:
- IC SUPERVISOR MPU 8-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,270
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Product details
Overview
MAX690REPA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with precision reset threshold of 2.625V (R-suffix), 200ms reset timeout, watchdog timer (1.6s), battery-backup switchover, and active-low RESET output. It monitors VCC for brownout and power-fail conditions while enabling CMOS RAM retention via VBATT–VOUT switching in embedded controllers and portable equipment.
For engineers reviewing the MAX690REPA+ datasheet, MAX690REPA+ pinout, MAX690REPA+ application, or MAX690REPA+ equivalent, this page delivers verified electrical parameters, thermal behavior across -40°C to +85°C, battery-switching hysteresis (25mV), PFI comparator accuracy (±75mV), and functional distinctions among R/S/T variants - all critical for reliable µP reset sequencing and backup-power integrity.
Technical Context
The MAX690REPA+ integrates a precision reset comparator with 2.625V nominal falling threshold (±75mV tolerance), 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 reset assertion is guaranteed down to VCC = 1V, and it supports manual reset with internal 70µA pull-up.
It features independent power-fail detection (PFI input referenced to 1.237V ±75mV) and battery switchover triggered when VCC falls below VSW = 2.40V (typ), with 200ms reset delay and guaranteed RESET deassertion only after VCC rises above VRST and holds for tWP. The device operates without short-circuit protection and requires external 0.1µF decoupling on VCC/VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold (VCC falling) | 2.55V to 2.70V (nominal 2.625V); ensures reset asserts before 3.0V supply drops below system minimum operating voltage |
| Reset Timeout Period | 140ms to 280ms (typ 200ms); guarantees µP remains held in reset long enough for stable power recovery |
| VCC Supply Current | 40µA (typ) at VCC < 3.6V; enables ultra-low-power operation in battery-backed systems |
| Battery Supply Current | 0.4µA to 1µA (max); minimizes drain on lithium backup cells during extended standby |
| Watchdog Timeout | 1.12s to 2.24s (typ 1.60s); provides deterministic fault recovery window for firmware hang detection |
| VBATT-to-VOUT On-Resistance | 140Ω (typ); limits voltage drop and power loss during battery switchover to CMOS RAM |
| PFI Input Threshold | 1.187V to 1.287V (nominal 1.237V); enables accurate undervoltage monitoring of auxiliary rails |
Pinout & Package
MAX690REPA+ is housed in an 8-pin plastic DIP (PDIP) package with through-hole mounting, RoHS-compliant lead-free finish (+ suffix), and 0.3-inch body width. Pin spacing conforms to JEDEC MS-001 standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω switch) based on VCC level relative to VSW |
| VCC | Main supply input | Primary 3.0V/3.3V power rail; powers internal circuitry and sources VOUT when above reset threshold |
| GND | Ground reference | Common return path for VCC, VBATT, and all logic signals; substrate tied to higher of VCC/VBATT |
| PFI | Power-fail input | Monitors auxiliary voltage against 1.237V reference; triggers PFO low when input falls below VPFT |
| PFO | Power-fail output | Open-drain active-low signal indicating PFI undervoltage or VCC falling below VSW |
| WDI | Watchdog input | Edge-sensitive input; clears 1.6s timer on rising/falling transition; cannot be disabled |
| RESET | Active-low reset output | Push-pull output asserted low during power-up, brownout, watchdog timeout, or MR activation |
| VBATT | Backup-battery input | Accepts up to 6.0V; supplies VOUT when VCC drops below VSW = 2.40V; may exceed VCC in normal operation |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout, critical for data retention in low-voltage states |
| Battery switchover with 25mV hysteresis | Prevents oscillation during VCC transitions near VSW = 2.40V, extending backup battery life |
| 40µA VCC supply current (typ) | Reduces quiescent load on primary supply, enabling longer runtime in always-on embedded systems |
| 1µA battery supply current (max) | Minimizes self-discharge of lithium coin cells, supporting >10-year backup in static RAM applications |
| 200ms reset time delay with restart-on-brownout | Provides consistent reset hold time regardless of transient depth or duration, improving system robustness |
Applications
| Battery-Powered Controllers | Embedded Industrial Controllers |
|---|---|
Use Scenario: Portable data loggers powered by 3.0V lithium batteries with SRAM retention requirements during main power loss. IC Role / Device Role / Timing Role: Supervisory IC providing VCC monitoring, automatic VBATT switchover, and 200ms reset pulse to initialize µP upon power restoration. Use Value: Guarantees RAM data integrity during brownouts and enables cold-start reliability without external reset circuitry. |
Use Scenario: Programmable logic controllers (PLCs) operating in factory environments with fluctuating 3.3V supplies and watchdog safety requirements. IC Role / Device Role / Timing Role: Dual-function supervisor delivering both power-fail warning (PFO) and hardware reset (RESET), synchronized with 1.6s watchdog timeout. Use Value: Eliminates need for discrete comparators and timers, reducing BOM count while meeting IEC 61508 functional safety timing constraints. |
| Intelligent Instrumentation | Critical µP Power Monitoring |
Use Scenario: Handheld multimeters with real-time clock and nonvolatile memory requiring precise low-voltage detection before shutdown. IC Role / Device Role / Timing Role: Precision voltage monitor using PFI input to detect auxiliary rail collapse and trigger controlled save-and-shutdown sequence via PFO interrupt. Use Value: Achieves ±75mV PFI threshold accuracy over temperature, enabling reliable early-warning detection of failing power rails. |
Use Scenario: Medical diagnostic devices where µP reset integrity directly impacts patient safety and regulatory compliance. IC Role / Device Role / Timing Role: Primary reset generator asserting RESET for ≥200ms with guaranteed validity down to VCC = 1V, independent of battery presence. Use Value: Meets ISO 13485 power-on reset timing requirements without software dependency or external components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690SEPA+ | Higher reset threshold (2.925V vs. 2.625V); tighter PFI tolerance (±2% vs. ±75mV) | Better suited for 3.3V ±10% systems; less margin for deep brownout detection | Select MAX690SEPA+ when monitoring 3.3V rails with wider supply tolerance and requiring earlier reset assertion |
| MAX706REPA+ | No watchdog or battery switchover; dedicated reset-only function; lower supply current (25µA) | Designed for cost-sensitive, non-backup applications; lacks PFO/PFI and WDI functionality | Choose MAX706REPA+ only if battery backup and watchdog are unnecessary and lowest possible quiescent current is required |
Compared with MAX690SEPA+, MAX690REPA+ offers deeper brownout detection but reduced noise immunity on PFI; compared with MAX706REPA+, it adds full backup-power management and watchdog capability at the cost of higher complexity and current draw.
Availability
MAX690REPA+ is available at Aetrix Electronics and suitable for battery-powered computers, embedded controllers, and intelligent instrumentation requiring stable component supply across industrial temperature ranges (-40°C to +85°C).
Supply support for MAX690REPA+ 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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications in industrial, automotive, and communications markets.
The MAX690 family targets 3.0V/3.3V microprocessor systems needing integrated reset, watchdog, and battery-backup control - eliminating discrete solutions while ensuring deterministic power-up, brownout, and fault-recovery behavior.
FAQ
What is the exact reset threshold voltage for MAX690REPA+?
The MAX690REPA+ has a nominal reset threshold of 2.625V for VCC falling, with a guaranteed range of 2.55V to 2.70V at TMIN to TMAX. This value is fixed by the 'R' suffix and applies specifically to the MAX690REPA+ variant - not shared with S- or T-suffix versions. The threshold exhibits ±75mV tolerance over temperature and supply variation, as confirmed in the Electrical Characteristics table.
Does MAX690REPA+ support battery voltage higher than VCC?
Yes, MAX690REPA+ explicitly supports VBATT exceeding VCC during normal operation. Its internal battery switchover circuit activates when VCC falls below VSW = 2.40V (typ), connecting VBATT to VOUT through a 140Ω switch. The datasheet confirms VBATT may be up to 6.0V, and lithium cells (e.g., 3.6V) are cited as valid use cases - a key design feature distinguishing MAX690REPA+ from simpler reset-only supervisors.
Can the watchdog timer in MAX690REPA+ be disabled?
No, the watchdog timer in MAX690REPA+ cannot be disabled. As stated in the Detailed Description section, "Unlike the 5V MAX690 family, the watchdog function cannot be disabled." It resets the µP if WDI remains static (high or low) for longer than 1.6s (1.12s–2.24s range), and the timer clears only on WDI edges or during active RESET assertion. This hardwired behavior ensures fail-safe operation in safety-critical applications.
What is the maximum allowable VCC transient duration that will not trigger reset in MAX690REPA+?
According to Figure 7 in the datasheet, MAX690REPA+ tolerates negative-going VCC transients up to 40µs in duration when the overdrive (VRST – VCC) is 100mV. For larger overdrives, the maximum allowed pulse width decreases - e.g., 10µs at 200mV overdrive. This immunity is achieved via internal filtering and is validated at TA = +25°C with VCC = 3.3V, ensuring robust operation in noisy power environments.
How does MAX690REPA+ handle power-fail detection when VCC drops below VSW?
When VCC falls below VSW = 2.40V (typ), MAX690REPA+ disables the PFI comparator and forces PFO low - providing a clean power-fail indication independent of the external PFI signal. This behavior is documented in Table 1 ("Input and Output Status in Battery-Backup Mode") and ensures reliable system shutdown signaling even if the monitored auxiliary rail remains stable while main supply collapses.
MAX690REPA+ 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:
- -
MAX690REPA+ FAQ
1.How can I place an order for MAX690REPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690REPA+ 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 MAX690REPA+ reliable?
The price and inventory of MAX690REPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690REPA+ is usually 5 days.
3.What payment methods are accepted for MAX690REPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690REPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690REPA+?
MAX690REPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690REPA+ 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 MAX690REPA+?
For technical support, including MAX690REPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690REPA+ requirements.
6.How does Aetrix verify that MAX690REPA+ is sourced from the original manufacturer or authorized distributors?
All MAX690REPA+ 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 MAX690REPA+ meets industry standards.
7.What is the process for return or replacement of MAX690REPA+?
All MAX690REPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX690REPA+, 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 MAX690REPA+ part is unused and in its original packaging.
Return procedure for MAX690REPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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