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Analog Devices Inc./Maxim Integrated MAX691EWE+
- Part No.:
- MAX691EWE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MAX691EWE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,807
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Product details
Overview
The MAX691EWE+ from Maxim Integrated is a 16-pin microprocessor supervisory circuit providing precision reset generation, battery backup switchover, watchdog timer, power-fail detection, and chip-enable gating for CMOS RAM/EEPROM. It features a 4.65V reset threshold, 200ms reset timeout, adjustable watchdog (100ms/1.6s), 1.3V PFI comparator, and VOUT switching between VCC and VBATT. It is used in industrial controllers and automotive ECUs requiring reliable µP power monitoring and data retention during brownouts.
For engineers reviewing the MAX691EWE+ datasheet, MAX691EWE+ pinout, MAX691EWE+ application, or MAX691EWE+ equivalent, key selection considerations include its E-suffix industrial temperature range (–40°C to +85°C), SOIC-16 package, integrated CE OUT write protection logic, BATT ON output for external PNP drive, and dual-mode oscillator (internal/external) for configurable timing - all critical for robust embedded system design.
Technical Context
The MAX691EWE+ implements a dual-threshold voltage monitor with 40mV hysteresis on its 4.65V reset comparator and a separate 1.3V reference for PFI-based power-fail warning. Its battery switchover uses a MOSFET-based architecture with 50mV/70mV asymmetric thresholds and 20mV hysteresis to prevent chatter during slow VCC transitions.
It integrates a programmable watchdog timer with selectable timeout periods (100ms or 1.6s) via OSC SEL/OSC IN pins, plus an active-high RESET output and WDO fault indicator. CE IN/CE OUT gating enforces write protection by forcing CE OUT high whenever VCC drops below 4.65V - independent of CE IN state - ensuring RAM integrity during undervoltage events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - guarantees reliable hold-down of µP reset line during 5V supply brownouts within ±10% tolerance. |
| Reset Timeout Delay | 200ms - provides extended reset assertion to accommodate slow-starting crystal oscillators in µP systems. |
| Battery Switchover Threshold | VCC – VBATT = 70mV (rising), 50mV (falling) - ensures clean, chatter-free transition between main and backup power sources. |
| Watchdog Timeout Period | Selectable 100ms or 1.6s - supports both fast software recovery and long-cycle firmware validation. |
| PFI Comparator Threshold | 1.3V ±100mV - enables precise early-warning detection of power failure or low-battery condition via external resistor divider. |
| Supply Current (Battery Backup) | 1µA max - minimizes drain on backup battery during extended VCC loss, extending shelf life of 3V lithium cells. |
| Operating Temperature Range | –40°C to +85°C (E suffix) - qualified for industrial and automotive under-hood applications without derating. |
Pinout & Package
MAX691EWE+ is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package with 1.27mm pitch, surface-mount footprint, and JEDEC MS-012AC compliance. The package supports reflow soldering and offers thermal resistance θJA = 120°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VCC | +5V main supply input; powers internal circuitry and sources VOUT when higher than VBATT. |
| 2 | VBATT | Backup battery input (2.0V–4.25V); automatically selected by internal switchover when VCC fails. |
| 3 | VOUT | Switched output delivering higher of VCC or VBATT; supplies up to 50mA to CMOS RAM or RTC. |
| 4 | GND | Ground reference for all analog and digital functions; must be low-impedance connection. |
| 5 | PFI | Noninverting input to 1.3V comparator; monitors external voltage divider for power-fail or low-battery warning. |
| 6 | PFO | Active-low power-fail output; asserts NMI or interrupt to µP when PFI falls below 1.3V. |
| 7 | WDI | Three-level watchdog input; toggling required every 100ms or 1.6s to prevent RESET pulse generation. |
| 8 | OSC SEL | Oscillator mode select; floating/high enables internal oscillator; low enables external clock/capacitor timing. |
| 9 | OSC IN | External timing input; accepts clock signal or capacitor to adjust watchdog/reset timing per Table 1. |
| 10 | WDO | Active-low watchdog fault output; indicates timeout event and remains low until next WDI transition. |
| 11 | RESET | Active-low reset output; asserted during power-up, brownout, or watchdog timeout; 200ms duration. |
| 12 | RESET | Active-high reset output; complementary to pin 11; useful for direct CMOS gate interfacing. |
| 13 | CE IN | Chip-enable gating input; controls CE OUT behavior; connect to GND if unused. |
| 14 | CE OUT | Controlled chip-enable output; forced high during undervoltage to block RAM writes regardless of CE IN. |
| 15 | BATT ON | Active-high battery-on indicator; sinks 25mA to drive base of external PNP transistor for >50mA VOUT loads. |
| 16 | LOW LINE | Active-low undervoltage flag; goes low immediately when VCC drops below 4.65V; returns high at threshold. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated CE Gating Logic | Forces CE OUT high during VCC undervoltage (<4.65V), preventing erroneous RAM writes without external logic. |
| Adjustable Watchdog Timing | Two selectable timeout periods (100ms/1.6s) via OSC SEL/OSC IN, enabling flexible firmware validation strategies. |
| Battery Switchover with Hysteresis | 50mV/70mV asymmetric thresholds + 20mV hysteresis eliminate oscillation during slow VCC decay or recovery. |
| Low Battery Backup Current | 1µA max supply current in battery mode extends 3V lithium cell life beyond 10 years under typical standby load. |
| Dual Reset Outputs | Both active-low (pin 11) and active-high (pin 12) RESET outputs simplify interface to diverse µP reset architectures. |
Applications
| Industrial PLC Controller | Automotive Body Control Module |
|---|---|
|
Use Scenario: Power monitoring and nonvolatile memory protection in programmable logic controllers operating in factory environments with fluctuating AC line-derived 5V supplies. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, battery-backed RAM switchover, and watchdog supervision of control firmware execution. Use Value: Prevents corrupted I/O state or lost ladder logic configuration during 5V rail dips by asserting RESET for 200ms and blocking RAM writes via CE OUT. |
Use Scenario: Ensuring safe shutdown and data retention in vehicle body electronics exposed to cold-crank (4.5V) and load-dump (18V) transients. IC Role / Device Role / Timing Role: Voltage supervisor detecting VCC collapse below 4.65V and triggering controlled EEPROM save before µP reset. Use Value: Enables storage of door/window position or lighting presets into backup RAM using VOUT powered by VBATT during ignition-off battery-only operation. |
| Medical Infusion Pump | Smart Energy Meter |
|
Use Scenario: Maintaining real-time clock and therapy history in battery-powered portable infusion devices requiring FDA-grade reliability. IC Role / Device Role / Timing Role: Dual-role supervisor: generating 200ms power-on reset and issuing PFO interrupt for early power-fail warning prior to VCC dropout. Use Value: Allows pump controller to complete current dose delivery and log final operational parameters into battery-backed RAM before shutdown. |
Use Scenario: Data logging and tamper-resistant timekeeping in utility meters deployed in unconditioned outdoor enclosures. IC Role / Device Role / Timing Role: Microprocessor supervisor with BATT ON output driving external PNP to sustain RTC and flash memory during mains outage. Use Value: Delivers >50mA VOUT current via external transistor while maintaining <1µA quiescent draw from backup coin cell over 10-year deployment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691CWE+ | Same functionality but C-suffix (0°C to +70°C) instead of E-suffix (–40°C to +85°C); identical pinout and electrical specs. | Suitable only for commercial-temperature applications; not rated for industrial or automotive ambient extremes. | Select MAX691CWE+ only if operating environment stays within 0°C–70°C and cost sensitivity outweighs temperature margin. |
| TPS3823MPWPT | Single-supply 5V supervisor with 4.63V reset threshold, 200ms delay, and watchdog; lacks battery switchover, CE gating, and PFI comparator. | Applicable where backup power and RAM write protection are unnecessary; no VOUT/VBATT switching capability. | Choose TPS3823MPWPT only for basic reset/watchdog needs without battery management or memory protection requirements. |
Compared with MAX691CWE+, the MAX691EWE+ adds industrial temperature qualification essential for field-deployed equipment; compared with TPS3823MPWPT, it delivers full supervisory integration - including switchover, CE gating, and PFI - eliminating 4–5 discrete components in battery-backed µP systems.
Availability
MAX691EWE+ is available at Aetrix Electronics and suitable for industrial controllers, automotive ECUs, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX691EWE+ 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 industrial, automotive, communications, and computing applications, with emphasis on high-reliability power management and interface solutions.
The MAX690–MAX695 family was developed specifically to consolidate µP supervisory functions - reset, watchdog, battery switchover, and power-fail detection - into single-chip solutions for space-constrained embedded systems demanding data integrity during power anomalies.
FAQ
What is the operating temperature range of the MAX691EWE+?
The MAX691EWE+ is specified for operation from –40°C to +85°C (E-suffix grade), making it suitable for industrial automation, automotive under-hood modules, and outdoor metering applications where ambient conditions exceed commercial temperature limits. This rating is confirmed in the Absolute Maximum Ratings table and validated across all electrical characteristics in the datasheet.
Does the MAX691EWE+ support adjustable reset timeout delay?
Yes, the MAX691EWE+ supports adjustable reset timeout delay via the OSC SEL and OSC IN pins. With OSC SEL floating and OSC IN low, the reset delay is 50ms; with OSC SEL floating and OSC IN floating, it is 200ms. External clock or capacitor configurations enable further customization per Table 1 in the MAX691EWE+ datasheet.
How does the CE OUT pin protect CMOS RAM during power failure?
The MAX691EWE+ forces CE OUT high whenever VCC drops below 4.65V - regardless of CE IN state - thereby disabling chip select to battery-backed RAM. This prevents spurious writes during brownout, power-up, or momentary interruption. The action is hardware-enforced with 50ns propagation delay and requires no firmware intervention.
Can the MAX691EWE+ drive more than 50mA on the VOUT pin?
No, the MAX691EWE+ VOUT pin is rated for 50mA maximum when sourced from VCC. For higher currents, the BATT ON output (pin 15) can sink 25mA to drive the base of an external PNP transistor, enabling VOUT to deliver >500mA while maintaining low dropout and preserving the 1µA battery backup current spec.
What is the function of the LOW LINE output on the MAX691EWE+?
The LOW LINE output (pin 16) is an active-low undervoltage flag that transitions low immediately when VCC falls below the 4.65V reset threshold and returns high as soon as VCC rises above that threshold. Unlike RESET, it has no built-in delay - providing instantaneous status feedback for system-level power monitoring or LED indicators.
MAX691EWE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Push-Pull, Push-Pull
- Reset:
- Active High/Active Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX691EWE+ FAQ
1.How can I place an order for MAX691EWE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691EWE+ 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 MAX691EWE+ reliable?
The price and inventory of MAX691EWE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691EWE+ is usually 5 days.
3.What payment methods are accepted for MAX691EWE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691EWE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691EWE+?
MAX691EWE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691EWE+ 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 MAX691EWE+?
For technical support, including MAX691EWE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691EWE+ requirements.
6.How does Aetrix verify that MAX691EWE+ is sourced from the original manufacturer or authorized distributors?
All MAX691EWE+ 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 MAX691EWE+ meets industry standards.
7.What is the process for return or replacement of MAX691EWE+?
All MAX691EWE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX691EWE+, 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 MAX691EWE+ part is unused and in its original packaging.
Return procedure for MAX691EWE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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