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Analog Devices Inc./Maxim Integrated MAX691AEWE+
- Part No.:
- MAX691AEWE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MAX691AEWE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,588
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Product details
Overview
The MAX691AEWE+ from Maxim Integrated is a microprocessor supervisory circuit designed for critical 5V power monitoring in industrial and embedded systems. It provides dual reset outputs (active-low RESET and active-high RESET), watchdog timer with selectable timeout (100ms or 1.6s), chip-enable gating (≤10ns propagation delay), battery switchover down to 1V VCC, and power-fail detection with ±2% accuracy - all in a -40°C to +85°C operating range.
For engineers reviewing the MAX691AEWE+ datasheet, MAX691AEWE+ pinout, MAX691AEWE+ application, or MAX691AEWE+ equivalent, this device serves as a pin-compatible upgrade to the legacy MAX691 with improved 30μA operating current, guaranteed RESET assertion down to VCC = 1V, and validated backup-battery operation using MaxCap®/SuperCap™ capacitors.
Technical Context
The MAX691AEWE+ integrates a precision voltage monitor (4.65V ±15mV reset threshold), internal oscillator (50kHz nominal), and dual-mode watchdog (programmable via OSC SEL/OSC IN). Its battery switchover logic activates when VCC falls below VBATT − 0.3V and remains asserted until VCC rises above VBATT + 0.3V, with 60mV hysteresis.
Chip-enable gating uses a low-resistance transmission gate (75–150Ω) between CE IN and CE OUT, enabling real-time bus protection during brownout. The PFI/PFO comparator operates independently with 1.25V threshold and 25–60μs response, supporting early power-fail warning without affecting reset timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V typical (MAX691A/MAX800L family); ensures reliable μP reset at 5V system brownout. |
| Reset Timeout Period | 200ms typical on power-up; guarantees stable initialization before code execution. |
| Supply Current | 30μA typical operating / 1μA standby; enables long-term battery-backed operation. |
| VCC-to-VOUT On-Resistance | 0.8–1.4Ω (−40°C to +85°C); supports up to 250mA load with ≤200mV dropout at full current. |
| Watchdog Timeout | 100ms (short) or 1.6s (long); configurable via OSC SEL/OSC IN for flexible firmware supervision. |
| Power-Fail Accuracy | ±2% (MAX800L variant); enables precise low-battery or early power-loss detection. |
| Operating Temperature | −40°C to +85°C; qualified for industrial control, instrumentation, and automotive under-hood edge cases. |
Pinout & Package
MAX691AEWE+ is housed in a 16-pin Wide SO (SOIC-W) package, 7.5mm × 10.3mm body, 1.27mm pitch, RoHS-compliant lead-free finish (denoted by '+' suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Battery-Backup Input | Accepts 2.0–5.5V backup source; enables seamless switchover when VCC drops below VBATT − 0.3V. |
| 2 VOUT | Output Supply Voltage | Switched output sourcing up to 250mA; connects to VCC or VBATT depending on supply status. |
| 3 VCC | Main 5V Supply Input | Regulated 4.75–5.5V input; powers internal circuitry and enables CE gating and reset generation. |
| 4 GND | Ground Reference | 0V reference for all analog comparators, digital logic, and output drivers. |
| 5 BATT ON | Battery-On Status Output | Open-drain high when VBATT is active; drives external PNP base for >250mA backup loads. |
| 6 LOW LINE | Reset Comparator Buffer | Active-low signal mirroring RESET threshold crossing; used for system status indication. |
| 7 OSC IN | Oscillator Timing Input | Accepts external capacitor (e.g., 47pF) or clock to set watchdog/reset timeouts. |
| 8 OSC SEL | Oscillator Mode Select | Logic high = internal oscillator; low = external timing; floating = default 1.6s/200ms mode. |
| 9 PFI | Power-Fail Input | Non-inverting comparator input; triggers PFO when voltage falls below 1.25V. |
| 10 PFO | Power-Fail Output | Open-drain output asserting low on PFI < 1.25V; independent of reset logic. |
| 11 WDI | Watchdog Input | Three-level input (high/low/floating); resets timer on transition; unconnected disables watchdog. |
| 12 CE OUT | Chip-Enable Output | Gated CE signal; disabled during reset to prevent RAM corruption during brownout. |
| 13 CE IN | Chip-Enable Input | High-impedance during reset; passes CE transitions only when VCC is valid and stable. |
| 14 WDO | Watchdog Output | Asserts low on watchdog timeout; synchronous with RESET and RESET outputs. |
| 15 RESET | Active-Low Reset Output | Open-drain output; sinks 3.2mA @ 0.1V; valid down to VCC = 1V; requires external pullup. |
| 16 RESET | Active-High Reset Output | Open-drain inverse of RESET; high-impedance when inactive; no internal pullup required. |
Key Features
| Feature | Design Value |
|---|---|
| Dual Reset Outputs | RESET (active-low) and RESET (active-high) provide native compatibility with both high- and low-active μP reset inputs. |
| Battery Switchover Down to 1V | Guaranteed RESET assertion with VCC as low as 1V enables robust data retention during deep brownout. |
| Chip-Enable Gating | ≤10ns CE IN-to-CE OUT propagation delay prevents spurious writes to CMOS RAM during power failure. |
| Configurable Watchdog | Hardware-selectable 100ms or 1.6s timeout via OSC SEL eliminates firmware dependency for critical supervision. |
| MaxCap®/SuperCap™ Compatible | Low-leakage design (≤1μA battery standby) supports long-life backup using large-value electrolytic alternatives. |
| Independent Power-Fail Comparator | PFI/PFO pair delivers ±2% accurate early warning without interfering with reset timing or watchdog behavior. |
Applications
| Industrial PLC Controllers | Medical Diagnostic Instruments |
|---|---|
|
Use Scenario: Programmable logic controllers operating in factory environments with fluctuating 5V rail stability. IC Role / Device Role / Timing Role: Supervises VCC, asserts RESET on brownout, gates CE during fault, and monitors battery backup for nonvolatile memory retention. Use Value: Prevents corrupted I/O state during voltage sags; maintains RAM integrity for 10+ years using MaxCap® backup. |
Use Scenario: Portable ultrasound or ECG units requiring fail-safe boot and runtime supervision. IC Role / Device Role / Timing Role: Generates 200ms power-on reset, detects low battery via PFI, and triggers audible alarm through WDO-driven indicator. Use Value: Ensures deterministic startup and patient-data safety; ±2% PFI accuracy avoids premature shutdown during transient dips. |
| Telecom Base Station Management | Automotive Infotainment Head Units |
|
Use Scenario: Remote radio unit controllers exposed to wide temperature swings and intermittent AC power. IC Role / Device Role / Timing Role: Monitors 5V supply, switches to supercap backup on AC loss, asserts LOW LINE for system logging, and gates CE to protect configuration EEPROM. Use Value: Enables graceful shutdown and state preservation across −40°C to +85°C; 30μA quiescent current extends backup runtime. |
Use Scenario: In-vehicle infotainment systems subject to load-dump and cold-crank conditions. IC Role / Device Role / Timing Role: Detects VCC collapse during engine cranking, holds RESET active until stable 5V returns, and uses BATT ON to enable external backup regulator. Use Value: Eliminates boot-loop failures; 1V minimum VCC reset guarantee ensures operation even during severe battery sag. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACWE+ | 0°C to +70°C temperature range; identical electrical specs and pinout. | Suitable for commercial-grade equipment without extended thermal requirements. | Select MAX691ACWE+ for cost-sensitive, non-industrial applications where ambient temperature stays within 0–70°C. |
| MAX693AEWE+ | 4.4V reset threshold (vs. 4.65V); otherwise identical package, pinout, and feature set. | Optimized for 5V systems with tighter tolerance margins or lower-voltage μPs. | Choose MAX693AEWE+ when system brownout occurs near 4.4V, or when migrating from legacy MAX693 designs. |
Compared with MAX691ACWE+ and MAX693AEWE+, the MAX691AEWE+ uniquely combines industrial temperature rating (−40°C to +85°C) with the 4.65V reset threshold, making it the only option qualified for harsh-environment applications requiring both extended thermal range and standard 5V brownout detection.
Availability
MAX691AEWE+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic instruments, telecom base station management, and automotive infotainment head units requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for MAX691AEWE+ 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 supervisory family was engineered to replace legacy μP supervisors with enhanced reliability, lower quiescent current, and integrated battery switchover - specifically targeting mission-critical embedded systems needing deterministic reset and watchdog behavior.
FAQ
What is the reset threshold voltage of the MAX691AEWE+?
The MAX691AEWE+ has a typical reset threshold voltage of 4.65V, with a guaranteed range of 4.50V to 4.75V over temperature. This value applies specifically to the MAX691A and MAX800L variants, and is confirmed in the Electrical Characteristics table of the official datasheet. The MAX691AEWE+ maintains this threshold across its full −40°C to +85°C operating range, with 15mV hysteresis to prevent chatter during slow voltage transitions.
Does the MAX691AEWE+ support battery backup operation below 1V VCC?
No - the MAX691AEWE+ guarantees RESET assertion down to VCC = 1V, but not below. When VCC falls below 1V, gate drive to the RESET output switch weakens, increasing RDS(ON) and saturation voltage. An external 10kΩ pulldown resistor on the RESET pin ensures valid logic-low output down to GND, but the internal reset generator itself ceases reliable operation below 1V. This specification is explicitly stated in the Detailed Description section of the MAX691A datasheet.
How is the watchdog timeout configured on the MAX691AEWE+?
The MAX691AEWE+ watchdog timeout is configured using the OSC SEL and OSC IN pins. With both pins floating or tied to VOUT, the default is 1.6s long timeout and 200ms reset period. Connecting OSC SEL to GND and adding a capacitor (e.g., 47pF) from OSC IN to GND selects programmable timeouts per Table 1. Driving OSC IN with an external clock enables cycle-accurate timeout control (1024/4096 cycles). These configurations are hardware-based and require no firmware intervention.
Can the MAX691AEWE+ be used with supercapacitors for backup power?
Yes - the MAX691AEWE+ is explicitly MaxCap® and SuperCap™ compatible, as stated in its Features list. Its battery-backup mode draws ≤1μA from VBATT when VCC is absent, and its low-leakage VBATT input (≤1μA reverse leakage) enables multi-year retention using 0.47F supercapacitors. The datasheet's Typical Operating Circuit shows direct integration with a 0.47F MaxCap and 1N4148 diode, confirming validated use in capacitor-based backup systems.
What is the function of the BATT ON pin on the MAX691AEWE+?
The BATT ON pin on the MAX691AEWE+ is an open-drain output that goes high when the internal switchover circuit connects VOUT to VBATT (i.e., during battery-backup mode). It sinks 3.2mA at 0.1V when active and sources ~10μA in backup mode. Its primary design purpose is to drive the base of an external PNP transistor for high-current backup loads (>250mA), as illustrated in the Typical Operating Circuit. It also serves as a direct system-level indicator of battery activation.
MAX691AEWE+ 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:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX691AEWE+ FAQ
1.How can I place an order for MAX691AEWE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691AEWE+ 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+ reliable?
The price and inventory of MAX691AEWE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691AEWE+ is usually 5 days.
3.What payment methods are accepted for MAX691AEWE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691AEWE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691AEWE+?
MAX691AEWE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691AEWE+ 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+?
For technical support, including MAX691AEWE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691AEWE+ requirements.
6.How does Aetrix verify that MAX691AEWE+ is sourced from the original manufacturer or authorized distributors?
All MAX691AEWE+ 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+ meets industry standards.
7.What is the process for return or replacement of MAX691AEWE+?
All MAX691AEWE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX691AEWE+, 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+ part is unused and in its original packaging.
Return procedure for MAX691AEWE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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