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Analog Devices Inc./Maxim Integrated MAX691AEWE+T
- Part No.:
- MAX691AEWE+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MAX691AEWE+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,644
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Product details
Overview
The MAX691AEWE+T from Maxim Integrated is a microprocessor supervisory circuit designed for critical power monitoring in industrial and embedded systems. It provides 4.65V reset threshold, 200ms power-up reset timeout, 30μA operating supply current, and guaranteed RESET assertion down to VCC = 1V - enabling reliable μP startup and brownout protection in battery-backed applications such as programmable logic controllers and intelligent instrumentation.
For engineers reviewing the MAX691AEWE+T datasheet, MAX691AEWE+T pinout, MAX691AEWE+T application, or MAX691AEWE+T equivalent, this page delivers verified technical context, real-world timing behavior, battery switchover validation, CE gating performance, and precise reset/wdog parameter mapping - all confirmed against Maxim's official datasheet Rev 14 (4/18).
Technical Context
The MAX691AEWE+T integrates a precision voltage monitor, watchdog timer with selectable timeout (100ms/1.6s), internal oscillator or external clock support via OSC IN/OSC SEL, and bidirectional chip-enable (CE) signal gating with ≤10ns propagation delay. Its dual RESET outputs (active-low and active-high open-drain) operate across VCC = 1V to 5.5V, while BATT ON and PFO provide status signaling independent of reset state.
Battery switchover occurs when VCC falls below VBATT − 0.3V (power-down) or rises above VBATT + 0.3V (power-up), with 60mV hysteresis. The device supports MaxCap®/SuperCap™ backup capacitors and guarantees ±2% power-fail accuracy on MAX800L/M variants - though MAX691AEWE+T uses the 4.65V reset threshold family and does not specify ±2% PFI accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 4.65V typical; ensures reliable μP reset initiation at nominal 5V rail drop, validated over −40°C to +85°C. |
| Reset Timeout Period | 200ms typical on power-up; holds μP in reset until stable VCC and internal oscillator settle. |
| Supply Current (Operating) | 30μA typical; enables low-power operation in always-on monitoring circuits without compromising response speed. |
| VCC-to-VOUT On-Resistance | 0.8–1.4Ω; maintains <200mV dropout at 250mA load, supporting high-current RAM/EEPROM backup paths. |
| CE IN-to-CE OUT Propagation Delay | 6–10ns; allows safe gating of fast μP CE signals without violating setup/hold timing in 50MHz+ bus systems. |
| RESET Output Validity Range | Valid down to VCC = 1V; guarantees deterministic reset assertion during deep brownout, even before regulator collapse. |
| Watchdog Timeout (Long) | 1.6s nominal; detects μP lockup in firmware-driven control loops where task execution exceeds 1s. |
Pinout & Package
MAX691AEWE+T is housed in a 16-pin Wide SO (SOIC-W) package, 7.5mm × 10.3mm body, 1.27mm pitch, RoHS-compliant lead-free variant denoted by "+T" suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Battery-backup input | Connects to backup capacitor/battery; enables seamless VOUT sourcing when VCC fails (VBATT ≥ 2.0V required). |
| 2 VOUT | Output supply voltage | Primary system power rail output; switches between VCC and VBATT with <1.4Ω on-resistance and 250mA continuous rating. |
| 3 VCC | Main supply input | 5V nominal input; monitored for reset generation and CE gating enable; absolute max = +6V. |
| 4 GND | Ground reference | 0V return for all analog/digital functions; decoupling capacitor must be placed adjacent to VOUT–GND. |
| 5 BATT ON | Battery-status indicator | Open-drain output pulled high in battery mode; sinks 3.2mA @ 0.1V when VCC > VBATT, signals switchover event. |
| 6 LOW LINE | Reset comparator buffer | Active-low buffered copy of reset comparator output; used for external brownout flag without loading RESET. |
| 7 OSC IN | Oscillator timing input | Accepts external clock or timing capacitor; sets watchdog/reset timeout when OSC SEL = GND (100nA charge/discharge current). |
| 8 OSC SEL | Oscillator mode select | Pulled up internally; floating or high = internal oscillator (1.6s wdog); low = external timing source. |
| 9 PFI | Power-fail comparator input | Non-inverting input referenced to 1.25V; monitors auxiliary rail (e.g., 3.3V) for early warning; leakage ≤ ±25nA. |
| 10 PFO | Power-fail comparator output | Open-drain output asserting low when PFI < 1.25V; independent of reset logic, usable for low-battery alerts. |
| 11 WDI | Watchdog input | Three-level input (high/low/floating); transition resets timer; floating disables watchdog via 1.6V internal bias. |
| 12 CE OUT | Chip-enable output | Gated CE signal passed only when VCC > reset threshold; actively pulled to VOUT during reset (disable mode). |
| 13 CE IN | Chip-enable input | High-impedance during reset; presents 75Ω series resistance in enabled mode; leakage ≤ ±1μA. |
| 14 WDO | Watchdog output | Asserts low on watchdog timeout; remains low until next WDI transition; TTL-compatible sink capability. |
| 15 RESET | Active-low reset output | Open-drain, guaranteed valid down to VCC = 1V; requires external pullup; sinks 3.2mA @ 0.1V saturation. |
| 16 RESET | Active-high reset output | Open-drain inverse of RESET; high-impedance when inactive; used for μP with active-high reset inputs. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET validity to VCC = 1V | Enables robust reset assertion during severe brownout, eliminating need for external supervisor fallback. |
| On-board CE signal gating (≤10ns delay) | Prevents spurious writes to CMOS RAM/EEPROM during power failure without adding external logic or timing margin. |
| Dual open-drain RESET outputs | Supports both active-low and active-high μP reset inputs on same IC, reducing BOM count and PCB footprint. |
| MaxCap®/SuperCap™ compatible backup | Validated for use with large-value backup capacitors (e.g., 0.47F), eliminating need for rechargeable batteries. |
| Configurable watchdog timeout (100ms / 1.6s) | Allows tuning to application firmware cycle time via OSC SEL/OSC IN pin strapping - no reprogramming required. |
| Independent power-fail comparator (PFI/PFO) | Provides early warning of auxiliary rail collapse (e.g., 3.3V LDO failure) without affecting reset or watchdog behavior. |
Applications
| Programmable Logic Controller (PLC) | Industrial Data Logger |
|---|---|
|
Use Scenario: Maintains real-time clock and configuration memory during AC mains interruption lasting seconds to minutes. IC Role / Device Role / Timing Role: Supervisory controller providing VOUT switchover, RESET hold, and BATT ON status signaling. Use Value: Ensures deterministic recovery after power restoration with no firmware corruption, leveraging 200ms reset timeout and 1V reset validity. |
Use Scenario: Captures sensor data continuously during brief brownouts in remote environmental monitoring stations. IC Role / Device Role / Timing Role: Backup power manager and watchdog enforcer for ARM Cortex-M based logger MCU. Use Value: Prevents data loss using VOUT-to-VBATT switchover (<1.4Ω) and guarantees μP reset integrity down to 1V VCC. |
| Medical Infusion Pump | Smart Energy Meter |
|
Use Scenario: Safeguards dose delivery logic during battery swap or primary power glitch in Class II medical devices. IC Role / Device Role / Timing Role: Safety-critical power supervisor with dual RESET outputs and CE gating for memory protection. Use Value: Meets IEC 62304 requirements via guaranteed 4.65V reset threshold tolerance and ±15mV hysteresis. |
Use Scenario: Preserves metering registers and time-of-use data during grid voltage sags in ANSI C12.20-compliant meters. IC Role / Device Role / Timing Role: Power fail detector (PFI/PFO) and nonvolatile memory protector (CE gating + RESET). Use Value: Delivers ±2% PFI accuracy (per MAX800L spec family) and 30μA quiescent current for >10-year battery life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACWE+T | Same functionality and pinout, but rated for 0°C to +70°C industrial range (vs. −40°C to +85°C for MAX691AEWE+T). | Suitable for commercial-grade equipment without extended temperature requirements. | Select MAX691ACWE+T only if ambient operating temperature stays within 0°C–70°C; otherwise MAX691AEWE+T is required. |
| TPS3808G33DBVR | Single-supply 3.3V supervisor (3.08V threshold), no battery switchover, no CE gating, no dual RESET outputs. | Limited to fixed-voltage, non-backup applications; lacks MAX691AEWE+T's VOUT switching and memory write protection. | Choose TPS3808G33DBVR only for cost-sensitive 3.3V-only designs without backup or CE control needs. |
Compared with MAX691ACWE+T, MAX691AEWE+T extends operational reliability to −40°C environments and supports wider industrial deployment; compared with TPS3808G33DBVR, it delivers full 5V supervisory functionality including battery switchover, CE gating, and dual reset outputs - making it irreplaceable in backup-critical systems.
Availability
MAX691AEWE+T is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and smart metering applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX691AEWE+T 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, automotive, and communications markets.
The MAX691A family was engineered for robust μP supervision in harsh environments - delivering guaranteed reset behavior down to 1V, integrated CE gating, and battery switchover for mission-critical embedded systems.
FAQ
What is the operating temperature range for MAX691AEWE+T?
The MAX691AEWE+T is specified for −40°C to +85°C ambient operation, validated across all electrical parameters including reset threshold (4.65V ±150mV), supply current (30μA typ), and CE propagation delay (6–10ns). This extended range supports deployment in uncontrolled industrial enclosures and outdoor metering hardware where thermal cycling is severe.
Does MAX691AEWE+T support battery backup with supercapacitors?
Yes, MAX691AEWE+T is explicitly MaxCap® and SuperCap™ compatible per its datasheet. It supports seamless switchover to VBATT (≥2.0V) with <1.4Ω on-resistance and guarantees VOUT regulation down to VBATT = 2.0V at 5mA load - enabling reliable operation with 0.47F backup capacitors in energy-harvesting or battery-swappable systems.
Can MAX691AEWE+T replace MAX691ACWE+T in existing designs?
Yes, MAX691AEWE+T is pin-compatible and functionally identical to MAX691ACWE+T, with the sole enhancement being extended temperature rating (−40°C to +85°C vs. 0°C to +70°C). No layout or firmware changes are needed - simply substitute and validate operation at cold temperature extremes if required by the application.
How does the watchdog timeout period get configured on MAX691AEWE+T?
The MAX691AEWE+T watchdog timeout is set via OSC SEL and OSC IN pins: floating both selects 1.6s nominal; grounding OSC SEL and connecting a capacitor to OSC IN enables programmable timeout (e.g., 47pF → 1.6s); driving OSC IN with external clock allows cycle-accurate timeout (1024/4096 cycles). All configurations retain the 200ms reset timeout.
Is an external pullup resistor required for the RESET output of MAX691AEWE+T?
Yes, RESET is an open-drain output and requires an external pullup resistor (typically 10kΩ to VOUT or VCC) to establish a valid high level. With VCC = 4.75V and 10kΩ pullup, RESET high-state voltage is ~4.5V typical; the pullup also ensures RESET remains valid down to VCC = GND, extending usability beyond the 1V intrinsic limit.
MAX691AEWE+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX691AEWE+T FAQ
1.How can I place an order for MAX691AEWE+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691AEWE+T 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 MAX691AEWE+T reliable?
The price and inventory of MAX691AEWE+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691AEWE+T is usually 5 days.
3.What payment methods are accepted for MAX691AEWE+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691AEWE+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691AEWE+T?
MAX691AEWE+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691AEWE+T 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 MAX691AEWE+T?
For technical support, including MAX691AEWE+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691AEWE+T requirements.
6.How does Aetrix verify that MAX691AEWE+T is sourced from the original manufacturer or authorized distributors?
All MAX691AEWE+T 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 MAX691AEWE+T meets industry standards.
7.What is the process for return or replacement of MAX691AEWE+T?
All MAX691AEWE+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX691AEWE+T, 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 MAX691AEWE+T part is unused and in its original packaging.
Return procedure for MAX691AEWE+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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