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Analog Devices Inc./Maxim Integrated MAX691ACPE+
- Part No.:
- MAX691ACPE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX691ACPE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,052
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Product details
Overview
The MAX691ACPE+ from Maxim Integrated is a microprocessor supervisory circuit in a 16-pin plastic DIP package, providing power-on reset, watchdog timer, battery switchover, and chip-enable gating functions. It features a 4.65V typical reset threshold, 200ms reset timeout, 30μA operating supply current, and guaranteed RESET assertion down to VCC = 1V - enabling reliable μP initialization in industrial controllers and intelligent instruments.
For engineers reviewing the MAX691ACPE+ datasheet, MAX691ACPE+ pinout, MAX691ACPE+ application, or MAX691ACPE+ equivalent, key selection criteria include reset threshold accuracy (±150mV), battery-backup mode operation with VBATT ≥ 2.0V, CE propagation delay ≤10ns, and compatibility with MaxCap®/SuperCap™ backup capacitors.
Technical Context
The MAX691ACPE+ integrates a precision voltage monitor, internal oscillator-based reset/watchdog timing, and bidirectional power-path control between VCC and VBATT. Its dual RESET/RESET outputs support both active-low and active-high μP reset inputs, while the BATT ON output signals switchover status and enables external pass-transistor drive.
Chip-enable gating uses a 75Ω series transmission gate with <10ns propagation delay (50Ω source, 50pF load), and the PFI/PFO comparator operates independently with ±25nA input leakage and 25–60μs response delay - supporting low-battery warning and early power-fail detection without affecting core supervision logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 4.65V typical (MAX691A variant); ensures reliable reset assertion during 5V system brownout down to 4.50V min. |
| Reset Timeout Period | 200ms typical on power-up; guarantees μP remains held in reset until supply stabilizes post-power-on. |
| Supply Current (Operating) | 30μA typical; enables low-power supervision in battery-backed systems without significant drain. |
| VCC-to-VOUT On-Resistance | 0.8–1.2Ω (MAX691AC); maintains <200mV drop at 250mA load, supporting stable CMOS RAM/EEPROM supply. |
| CE IN-to-CE OUT Propagation Delay | 6–10ns (50Ω source, 50pF load); preserves timing integrity for high-speed μP bus gating during fault conditions. |
| Battery Switchover Threshold | VCC < VBATT − 0.3V (power-down); cleanly transitions VOUT from VCC to VBATT with 60mV hysteresis. |
| RESET Output Type | Open-drain, active-low; sinks 3.2mA @ 0.1V saturation, compatible with standard pull-up configurations. |
Pinout & Package
Package: 16-pin plastic DIP (0.3-inch width), through-hole mount, RoHS-compliant with + symbol suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VBATT) | Battery-Backup Input | Accepts 2.0–5.5V backup source; enables VOUT switchover when VCC falls below reset threshold and VBATT. |
| 2 (VOUT) | Output Supply Voltage | Switched output sourced from VCC or VBATT; powers external RAM/EEPROM and drives all open-drain outputs high. |
| 3 (VCC) | Main Supply Input | 5V nominal input (4.75–5.5V); monitored for reset generation and CE gating enable/disable control. |
| 4 (GND) | Ground Reference | 0V reference for all analog comparators, digital logic, and output drivers; requires low-impedance connection. |
| 5 (BATT ON) | Battery-On Status Output | Active-high open-drain signal indicating VBATT is active; sources ~10μA in backup mode, sinks 3.2mA when VCC active. |
| 6 (LOW LINE) | Reset Comparator Buffer | Direct buffered output of reset threshold comparator; asserts low during brownout, independent of RESET timing. |
| 7 (OSC IN) | External Oscillator Input | Configurable timing node: accepts capacitor (for RC oscillator) or external clock; sets watchdog/reset timeout periods. |
| 8 (OSC SEL) | Oscillator Select Control | Logic input selecting internal oscillator (high/floating) or external timing (low); includes 10μA internal pull-up. |
| 9 (PFI) | Power-Fail Input | Noninverting input to uncommitted comparator; triggers PFO low when voltage drops below 1.25V ±25mV. |
| 10 (PFO) | Power-Fail Output | Open-drain comparator output; used for low-battery warning or pre-fail alert without affecting reset functionality. |
| 11 (WDI) | Watchdog Input | Three-level input (high/mid/low); resets watchdog timer on any transition; floating disables watchdog (biased to 1.6V). |
| 12 (CE OUT) | Chip-Enable Output | Gated CE signal passed only when VCC > reset threshold; disabled during reset to prevent RAM corruption. |
| 13 (CE IN) | Chip-Enable Input | High-impedance input during reset; presents 75Ω series resistance in enabled mode for minimal signal degradation. |
| 14 (WDO) | Watchdog Output | Active-low watchdog fault indicator; goes low if WDI stalls >1.6s, asserting RESET for 200ms timeout period. |
| 15 (RESET) | Active-Low Reset Output | Primary reset signal; asserted low during brownout, power-down, or watchdog timeout; valid down to VCC = 1V. |
| 16 (RESET) | Active-High Reset Output | Inverted open-drain output; complements RESET for μPs requiring active-high reset; high-impedance when inactive. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET validity to VCC = 1V | Ensures deterministic μP reset even during deep brownout, eliminating need for external reset extenders. |
| MaxCap®/SuperCap™ compatible backup | Supports large-value backup capacitors (e.g., 0.47F) via low-loss VBATT path with 15Ω typical on-resistance. |
| Independent power-fail comparator (PFI/PFO) | Enables early warning of supply degradation without interfering with reset/watchdog timing or state machine. |
| 10ns max CE propagation delay | Preserves μP bus timing integrity during supervision events, compatible with fast 8/16-bit microcontrollers. |
| Configurable watchdog timeout (100ms / 1.6s) | Allows tuning to application software cycle time via OSC SEL/OSC IN pin states or external capacitor. |
| Open-drain RESET and RESET outputs | Permits wired-OR reset bus architectures and flexible pull-up voltage selection (e.g., 3.3V or 5V domains). |
Applications
| Industrial Controllers | Intelligent Instruments |
|---|---|
|
Use Scenario: PLCs and RTUs operating in harsh environments with fluctuating 5V supplies and battery-backed memory. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, watchdog monitoring, and seamless RAM backup switchover. Use Value: Prevents firmware corruption during line sags by holding μP in reset until VCC stabilizes above 4.50V and maintaining VOUT from VBATT during outages. |
Use Scenario: Portable multimeters and data loggers requiring long-term nonvolatile storage and low-power sleep modes. IC Role / Device Role / Timing Role: Power supervisor managing VCC/VBATT arbitration, generating timed reset pulses, and signaling low-battery via PFO. Use Value: Extends operational life using 0.47F supercapacitor backup and delivers accurate low-battery alerts with ±2% PFI threshold tolerance. |
| Critical μP Power Monitoring | Computers (Embedded/Single-Board) |
|
Use Scenario: Medical diagnostic equipment where undetected reset failure could compromise patient safety. IC Role / Device Role / Timing Role: Dual-reset supervisor with independent RESET/RESET outputs and 200ms timeout guaranteeing safe boot sequence. Use Value: Eliminates race conditions via guaranteed 1V-minimum RESET assertion and prevents false releases during marginal VCC recovery. |
Use Scenario: Industrial PCs and SBCs with CMOS configuration RAM needing write protection during power faults. IC Role / Device Role / Timing Role: Chip-enable gate controller disabling CE signals during reset to block spurious writes to RAM/EEPROM. Use Value: Uses sub-10ns CE propagation delay to maintain bus timing while blocking errant accesses during 200ms reset window. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691AEPE+ | Extended temperature range (−40°C to +85°C) vs. MAX691ACPE+ (0°C to +70°C); identical electrical specs and pinout. | Suitable for automotive under-hood or outdoor industrial deployments requiring wider thermal margin. | Select MAX691AEPE+ when operating ambient exceeds 70°C or requires industrial-grade qualification. |
| MAX693ACPE+ | Lower 4.40V typical reset threshold (vs. 4.65V); same package, pinout, and feature set except reset voltage and PFI accuracy. | Better suited for 5V systems with tighter supply tolerances or legacy designs calibrated to 4.4V reset point. | Choose MAX693ACPE+ only if system brownout behavior is validated at 4.4V threshold; not a drop-in replacement. |
Compared with MAX691AEPE+, the MAX691ACPE+ offers lower cost for commercial-temperature applications, while MAX693ACPE+ shifts reset sensitivity downward - requiring revalidation of power-fail timing margins and software watchdog timeouts.
Availability
MAX691ACPE+ is available at Aetrix Electronics and suitable for industrial controllers, intelligent instruments, critical μP power monitoring, and embedded computers requiring stable component supply across extended production lifecycles.
Supply support for MAX691ACPE+ 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 systems.
The MAX691A family was designed as pin-compatible upgrades to legacy supervisory circuits, delivering lower quiescent current (30μA), faster CE propagation (<10ns), and enhanced battery switchover reliability for μP-based embedded systems.
FAQ
What is the reset threshold voltage of the MAX691ACPE+?
The MAX691ACPE+ has a typical reset threshold voltage of 4.65V, with a guaranteed minimum of 4.50V and maximum of 4.75V over temperature. This value is specific to the MAX691A variant and differs from the 4.40V threshold of the MAX693A series. The MAX691ACPE+ maintains this specification across its 0°C to +70°C operating range.
Does the MAX691ACPE+ support battery backup with supercapacitors?
Yes, the MAX691ACPE+ is explicitly MaxCap® and SuperCap™ compatible. Its VBATT input supports low-loss switchover to backup sources including 0.47F supercapacitors, with VBATT-to-VOUT on-resistance of 15–30Ω depending on voltage - enabling efficient energy transfer during main supply failure.
Can the MAX691ACPE+ watchdog timer be disabled?
Yes, the MAX691ACPE+ watchdog function is disabled by leaving the WDI pin unconnected. An internal voltage divider biases WDI to ~1.6V, which the internal comparators recognize as an invalid level, halting watchdog timing. No external components are required to disable this feature on the MAX691ACPE+.
What is the maximum continuous current supported on the VOUT pin of the MAX691ACPE+?
The MAX691ACPE+ supports up to 250mA continuous current on the VOUT pin when sourced from VCC, with a typical VCC-to-VOUT drop of 200mV at full load. When powered from VBATT, continuous current must be limited to 25mA due to higher on-resistance; exceeding this risks thermal overstress or voltage droop in the MAX691ACPE+ backup path.
Is the MAX691ACPE+ pin-compatible with the original MAX691?
Yes, the MAX691ACPE+ is a direct pin-compatible upgrade to the MAX691, offering improved specifications including 30μA supply current (vs. older versions), 200ms reset timeout, and 6ns CE propagation delay. All 16-pin DIP connections, signal names, and functional behavior are preserved - allowing drop-in replacement without PCB modification.
MAX691ACPE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- 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:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
MAX691ACPE+ FAQ
1.How can I place an order for MAX691ACPE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691ACPE+ 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 MAX691ACPE+ reliable?
The price and inventory of MAX691ACPE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691ACPE+ is usually 5 days.
3.What payment methods are accepted for MAX691ACPE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691ACPE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691ACPE+?
MAX691ACPE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691ACPE+ 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 MAX691ACPE+?
For technical support, including MAX691ACPE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691ACPE+ requirements.
6.How does Aetrix verify that MAX691ACPE+ is sourced from the original manufacturer or authorized distributors?
All MAX691ACPE+ 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 MAX691ACPE+ meets industry standards.
7.What is the process for return or replacement of MAX691ACPE+?
All MAX691ACPE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX691ACPE+, 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 MAX691ACPE+ part is unused and in its original packaging.
Return procedure for MAX691ACPE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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