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Analog Devices Inc./Maxim Integrated MAX691ACSE+
- Part No.:
- MAX691ACSE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX691ACSE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
MAX691ACSE+ from Maxim Integrated is a microprocessor supervisory circuit that monitors 5V supply voltage, asserts reset below 4.65V typical threshold, provides 200ms power-up reset timeout, enables chip-enable gating with ≤10ns propagation delay, and supports battery switchover down to VCC = 1V. It is used in embedded controllers and intelligent instruments requiring reliable power-on initialization and brownout protection.
For engineers reviewing the MAX691ACSE+ datasheet, MAX691ACSE+ pinout, MAX691ACSE+ application, or MAX691ACSE+ equivalent, key selection criteria include guaranteed RESET assertion at VCC = 1V, ±2% power-fail accuracy (MAX800L/M variant), 30μA operating current, and 16-pin narrow SO package compatibility with legacy MAX691 designs.
Technical Context
The MAX691ACSE+ integrates a precision voltage monitor, watchdog timer with selectable 100ms/1.6s timeout, internal oscillator or external clock support via OSC IN/OSC SEL, and bidirectional CE signal gating using a 75Ω transmission gate. Its dual RESET/RESET outputs provide active-low and active-high reset signaling for μP systems with either polarity requirement.
Battery switchover is controlled by a comparator with 60mV hysteresis, enabling seamless transition to VBATT when VCC falls below VBATT − 0.3V. The PFI/PFO comparator operates independently with 1.25V threshold and 25μs response time, supporting low-battery warning without affecting reset logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 4.65V typical; ensures reliable reset assertion before 5V μP brownout |
| Reset Timeout Period | 200ms typical on power-up; meets μP minimum reset hold time requirements |
| Supply Current (Operating) | 30μA typical; enables low-power operation in always-on monitoring applications |
| CE Propagation Delay | ≤10ns; supports high-speed μP bus timing without CE skew |
| VCC-to-VOUT On-Resistance | 0.8–1.2Ω; limits voltage drop under 250mA load to <300mV |
| Power-Fail Accuracy | ±2% (MAX800L/M); enables precise early-warning detection for system shutdown sequencing |
| RESET Valid Down To | VCC = 1V; guarantees reset integrity during deep brownout conditions |
Pinout & Package
MAX691ACSE+ is housed in a 16-pin narrow SO (Small Outline) package with standard JEDEC MS-012AC footprint, 1.27mm pitch, and gull-wing leads. Thermal performance supports 696mW continuous dissipation at +70°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Battery backup input | Connects to backup capacitor or battery; enables VOUT sourcing when VCC fails |
| 2 VOUT | Output supply voltage | Switched output sourced from VCC or VBATT; powers downstream RAM/EEPROM |
| 3 VCC | Main supply input | 5V regulated input; monitored for reset generation and CE gating control |
| 4 GND | Ground reference | 0V return for all analog and digital functions; decoupling required at VOUT |
| 5 BATT ON | Battery status indicator | Open-drain output high when VBATT is active; drives PNP base for >250mA loads |
| 6 LOW LINE | Reset comparator buffer | Active-low signal mirroring VCC vs. reset threshold; used for system status indication |
| 7 OSC IN | Oscillator timing input | Accepts external capacitor or clock; sets watchdog/reset timeout periods |
| 8 OSC SEL | Oscillator mode select | High = internal oscillator; low = external timing source; 10μA internal pull-up |
| 9 PFI | Power-fail comparator input | Non-inverting input referenced to 1.25V; detects supply sag or battery depletion |
| 10 PFO | Power-fail comparator output | Open-drain output low when PFI < 1.25V; independent of reset logic |
| 11 WDI | Watchdog input | Three-level input; transition resets timer; floating disables watchdog (biased to 1.6V) |
| 12 CE OUT | Chip-enable output | Gated CE signal passed only when VCC > reset threshold; prevents RAM corruption |
| 13 CE IN | Chip-enable input | High-impedance when reset asserted; 75Ω series resistance in enabled mode |
| 14 WDO | Watchdog output | Active-low open-drain output; asserts on watchdog timeout, mirrors RESET |
| 15 RESET | Active-low reset output | Open-drain output; sinks 3.2mA at 0.1V; valid down to VCC = 1V |
| 16 RESET | Active-high reset output | Open-drain output; inverse of RESET; high-impedance when not asserted |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion at VCC = 1V | Enables robust reset behavior during severe brownout, eliminating need for external reset supervisor |
| On-board CE signal gating with ≤10ns delay | Prevents spurious writes to CMOS RAM during power failure without adding board-level logic |
| MaxCap®/SuperCap compatible battery switchover | Supports low-ESR backup capacitors up to 0.47F without external diode or FET |
| Dual active-low and active-high RESET outputs | Direct interface to μPs requiring either reset polarity, reducing level-shifting components |
| Independent PFI/PFO comparator | Provides configurable low-battery or early power-fail warning without interfering with reset timing |
Applications
| Industrial Controller Power Monitoring | Embedded Data Logger with Battery Backup |
|---|---|
Use Scenario: PLC or RTU monitoring 5V rail in factory automation environment with intermittent power interruptions. IC Role / Device Role / Timing Role: Supervisory IC asserting RESET until stable 5V is confirmed; gating CE to prevent corrupted firmware writes during brownout. Use Value: Prevents controller lockup and memory corruption during grid sags, ensuring deterministic recovery without manual reset. | Use Scenario: Remote environmental sensor node logging data to EEPROM with supercapacitor backup during AC loss. IC Role / Device Role / Timing Role: Seamlessly switches VOUT from VCC to VBATT at 4.65V threshold; asserts RESET to halt μP before voltage collapse. Use Value: Enables uninterrupted data capture across power cycles with no firmware intervention or external switchover circuitry. |
| Medical Diagnostic Instrument | Point-of-Sale Terminal |
Use Scenario: Portable ultrasound device requiring fail-safe boot sequence and battery-backed configuration storage. IC Role / Device Role / Timing Role: Monitors main 5V supply and asserts both RESET and RESET outputs to initialize FPGA and μP simultaneously. Use Value: Guarantees known hardware state at power-on and preserves calibration data in nonvolatile memory during brief outages. | Use Scenario: Retail terminal with EEPROM-based transaction log and real-time clock, subject to unclean AC disconnects. IC Role / Device Role / Timing Role: Uses PFI/PFO to trigger graceful shutdown sequence before VCC drops below 4.65V; holds RESET until safe state is saved. Use Value: Eliminates transaction loss and file system corruption during unexpected power loss, meeting PCI compliance requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACPE+ | Same electrical specs and pinout; packaged in 16-pin plastic DIP instead of narrow SO | Suitable for through-hole prototyping or legacy PCBs with DIP footprints | Select for hand-soldered evaluation or replacement in existing DIP-based designs |
| MAX693ACSE+ | 4.4V reset threshold (vs. 4.65V); otherwise identical pinout, timing, and features | Used where tighter 5V tolerance is required, e.g., systems with marginal LDO regulation | Choose when system VCC nominal is 5.0V ±2% and brownout margin must be reduced |
Compared with MAX691ACSE+, MAX691ACPE+ offers identical functionality in through-hole packaging for prototyping, while MAX693ACSE+ provides lower reset threshold for tighter supply tolerance-neither is pin-compatible with MAX691ACSE+ in thermal or layout-sensitive high-density SO designs.
Availability
MAX691ACSE+ is available at Aetrix Electronics and suitable for industrial controllers, medical diagnostic instruments, and point-of-sale terminals requiring stable component supply and long-term production continuity.
Supply support for MAX691ACSE+ 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, sensing, and interface applications in industrial, automotive, and communications markets.
The MAX691A family targets μP supervisory functions including reset generation, watchdog monitoring, battery switchover, and CE gating-optimized for reliability-critical embedded systems with 5V rails.
FAQ
What is the reset threshold voltage of the MAX691ACSE+?
The MAX691ACSE+ has a typical reset threshold voltage of 4.65V, with a guaranteed range of 4.50V to 4.75V over temperature. This threshold is fixed and applies to both RESET and RESET outputs. The device asserts reset whenever VCC falls below this threshold and maintains it for 200ms after VCC rises above the threshold during power-up. This specification is validated per the MAX691A datasheet revision 14, section "Electrical Characteristics".
Does the MAX691ACSE+ support battery backup operation?
Yes, the MAX691ACSE+ supports battery backup operation via its VBATT pin. When VCC falls below the reset threshold and also drops below VBATT minus 0.3V, the device automatically switches VOUT from VCC to VBATT. In this mode, VOUT remains valid, RESET stays asserted, and BATT ON goes high. The MAX691ACSE+ guarantees VOUT sourcing capability down to VBATT = 2.0V and draws only 1μA max from the battery in backup mode.
Can the MAX691ACSE+ be used with a 3.3V microprocessor?
No, the MAX691ACSE+ is designed specifically for 5V systems: its reset threshold is 4.65V typical, VCC operating range is 4.75V to 5.5V, and all outputs (RESET, WDO, PFO, etc.) are referenced to VOUT/VCC-not a separate I/O voltage. Using it with a 3.3V μP would result in invalid reset assertion and potential damage due to overvoltage on inputs. For 3.3V applications, consider the MAX6326 or MAX6369 families instead.
How does the watchdog function work on the MAX691ACSE+?
The MAX691ACSE+ watchdog monitors the WDI pin: if WDI remains static (high or low) longer than the timeout period (1.6s nominal), WDO and both RESET outputs are asserted for 200ms. A transition (edge or ≥100ns pulse) resets the timer. Leaving WDI unconnected disables the watchdog via internal 100kΩ bias to ~1.6V. The timeout can be shortened to 100ms or adjusted with an external capacitor on OSC IN, as detailed in Table 1 of the MAX691A datasheet.
What package type is the MAX691ACSE+ supplied in?
The MAX691ACSE+ is supplied in a 16-pin narrow SO (Small Outline) package, also referred to as SOIC-NB or MS-012AC, with 1.27mm lead pitch and gull-wing leads. It is RoHS-compliant and lead-free, indicated by the "+" suffix. This package is pin-compatible with the legacy MAX691CSE but offers improved thermal performance (696mW at +70°C) and lower profile than wide SO or DIP variants.
MAX691ACSE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm 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:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX691ACSE+ FAQ
1.How can I place an order for MAX691ACSE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691ACSE+ 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 MAX691ACSE+ reliable?
The price and inventory of MAX691ACSE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691ACSE+ is usually 5 days.
3.What payment methods are accepted for MAX691ACSE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691ACSE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691ACSE+?
MAX691ACSE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691ACSE+ 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 MAX691ACSE+?
For technical support, including MAX691ACSE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691ACSE+ requirements.
6.How does Aetrix verify that MAX691ACSE+ is sourced from the original manufacturer or authorized distributors?
All MAX691ACSE+ 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 MAX691ACSE+ meets industry standards.
7.What is the process for return or replacement of MAX691ACSE+?
All MAX691ACSE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX691ACSE+, 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 MAX691ACSE+ part is unused and in its original packaging.
Return procedure for MAX691ACSE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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