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Analog Devices Inc./Maxim Integrated MAX691ACSE+T
- Part No.:
- MAX691ACSE+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX691ACSE+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
The MAX691ACSE+T from Maxim Integrated is a microprocessor supervisory circuit designed for 5V systems, providing power-on reset, watchdog timer, battery switchover, and chip-enable gating. 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 operation in critical μP power monitoring applications such as industrial controllers and intelligent instruments.
For engineers reviewing the MAX691ACSE+T datasheet, MAX691ACSE+T pinout, MAX691ACSE+T application, or MAX691ACSE+T equivalent, key selection considerations include its dual RESET/RESET outputs, battery-backup mode with VBATT-to-VOUT on-resistance ≤30Ω, ±2% power-fail accuracy (MAX800L variant), and 6ns CE propagation delay under 50pF load - all validated for narrow SO-16 packaging and 0°C to +70°C operation.
Technical Context
The MAX691ACSE+T integrates a precision voltage monitor with hysteresis (15mV), an internal oscillator setting 200ms reset timeout and 1.6s watchdog period, and a bidirectional VCC/VBATT switchover path controlled by a comparator with 60mV hysteresis. Its CE gating uses a 75–150Ω transmission gate with 6–10ns propagation delay, while WDI accepts three-level logic (floating = watchdog disabled) and triggers reset via open-drain WDO.
RESET is active-low open-drain (sinking 3.2mA @ 0.1V), RESET is active-high open-drain (sourcing 1.6mA @ VOUT − 0.5V), and both remain valid across VCC = 0–5.5V when VBATT ≥ 2V. In battery-backup mode (VCC < VBATT − 1.2V), VOUT connects to VBATT, BATT ON goes high, and watchdog/CE functions are disabled per datasheet Table 2.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 4.65V typical (MAX691A/MAX800L); ensures reliable reset assertion during 5V brownout down to 4.50V min. |
| Reset Timeout Period | 200ms typical (power-up); guarantees μP initialization completes before code execution begins. |
| Supply Current (Operating) | 30μA typical; enables low-power system monitoring without burdening 5V rail. |
| VCC-to-VOUT On-Resistance | 0.8–1.2Ω (MAX69_AC); supports up to 250mA continuous load with ≤200mV dropout at full current. |
| Watchdog Timeout (Long) | 1.6s typical; detects μP lockup with sufficient margin to avoid false triggers during normal software delays. |
| CE Propagation Delay | 6–10ns (50Ω source, 50pF load); preserves timing integrity for fast μP bus cycles without added latency. |
| Power-Fail Accuracy | ±2% (MAX800L/M only); enables precise early-warning detection of supply sag before reset threshold is crossed. |
Pinout & Package
MAX691ACSE+T is housed in a 16-pin narrow SOIC (SO-16N) package with 1.27mm pitch, RoHS-compliant lead-free finish (+T suffix), and thermal performance rated for 696mW at +70°C (derating 8.70mW/°C above).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Battery-backup input | Connects to backup capacitor or battery; enables seamless switchover when VCC falls below VBATT − 1.2V. |
| 2 VOUT | Output supply voltage | Primary system supply output; sourced from VCC (normal) or VBATT (backup); requires 0.1µF decoupling. |
| 3 VCC | Main 5V supply input | Regulated 4.75–5.5V input; powers internal circuitry and drives VOUT via low-RDS(ON) PMOS switch. |
| 4 GND | Ground reference | 0V return for all signals and power paths; must be low-impedance connection to minimize noise coupling. |
| 5 BATT ON | Battery-status indicator | Open-drain output high when VBATT is active; sources ~10µA in backup mode; drives PNP base for >250mA loads. |
| 6 LOW LINE | Reset-threshold comparator output | Active-low buffered flag indicating VCC < 4.65V; sinks 3.2mA @ 0.1V; used for system status indication. |
| 7 OSC IN | Oscillator timing input | Accepts external capacitor (e.g., 47pF) or clock signal to configure reset/watchdog timeout periods. |
| 8 OSC SEL | Oscillator mode select | High/floating = internal oscillator (1.6s/200ms); low = external timing control; has 10µA internal pull-up. |
| 9 PFI | Power-fail comparator input | Non-inverting input referenced to 1.25V; leakage ≤±25nA; used for low-battery or pre-fail warning. |
| 10 PFO | Power-fail comparator output | Active-low open-drain output; asserts when PFI < 1.25V; independent of reset/watchdog logic. |
| 11 WDI | Watchdog input | Three-level input (high/low/floating); transition resets timer; floating disables watchdog (biased to 1.6V). |
| 12 CE OUT | Chip-enable gated output | Passes CE IN only when VCC > reset threshold; prevents RAM corruption during power failure. |
| 13 CE IN | Chip-enable gated input | High-impedance during reset; series 75Ω resistance in enabled mode; connect to μP CE or GND if unused. |
| 14 WDO | Watchdog output | Active-low open-drain; asserts with WDI timeout; remains low until next WDI edge; TTL-compatible drive. |
| 15 RESET | Active-low reset output | Open-drain; sinks 3.2mA @ 0.1V; asserted for 200ms after VCC rises above 4.65V; valid to VCC = 1V. |
| 16 RESET | Active-high reset output | Open-drain; sources 1.6mA @ VOUT − 0.5V; inverse of RESET; high-impedance when VCC < 1V. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Enables fail-safe reset signaling even during deep brownout, eliminating need for external reset IC in low-VCC scenarios. |
| MaxCap®/SuperCap-compatible battery switchover | Supports direct connection to large-value backup capacitors (e.g., 0.47F) with controlled VBATT-to-VOUT on-resistance ≤30Ω. |
| On-board CE signal gating (10ns max delay) | Prevents spurious writes to CMOS RAM during power transitions without requiring external logic or layout changes. |
| Dual active-low and active-high RESET outputs | Directly interfaces with μPs requiring either reset polarity, eliminating level-shifting components in mixed-voltage designs. |
| Independent power-fail comparator (PFI/PFO) | Provides early warning of supply degradation without affecting reset timing or watchdog behavior - critical for graceful shutdown. |
Applications
| Industrial Controller Power Monitoring | Intelligent Instrument Data Retention |
|---|---|
|
Use Scenario: PLC or CNC controller maintaining real-time state during AC line sags or battery-backed operation. IC Role / Device Role / Timing Role: Supervisory circuit asserting RESET and switching VOUT to VBATT within 12µs of VCC drop below 4.65V. Use Value: Prevents firmware corruption and preserves volatile register contents using integrated CE gating and 200ms reset hold time. |
Use Scenario: Handheld multimeter or data logger retaining calibration and measurement history during battery replacement. IC Role / Device Role / Timing Role: Battery switchover controller enabling seamless VOUT sourcing from VBATT while asserting BATT ON for status feedback. Use Value: Guarantees uninterrupted power to CMOS RAM/EEPROM via sub-1V-valid RESET and ≤30Ω VBATT-to-VOUT path. |
| Critical μP System Boot Integrity | Embedded Computer Power Sequencing |
|
Use Scenario: Medical diagnostic device requiring deterministic boot sequence after cold start or brownout recovery. IC Role / Device Role / Timing Role: Reset generator with 200ms timeout and 1.6s watchdog enforcing μP initialization before peripheral enable. Use Value: Eliminates race conditions between CPU core startup and peripheral configuration via synchronized RESET/RESET deassertion. |
Use Scenario: Network appliance with multiple voltage rails where 5V main supply must stabilize before enabling downstream regulators. IC Role / Device Role / Timing Role: Power-good monitor using LOW LINE output to gate enable signals for secondary DC/DC converters. Use Value: Provides clean, jitter-free 5V power-ok signal with 800ns delay and 3.2mA drive strength - no external buffer needed. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691AESE+ | Extended temperature range (−40°C to +85°C); identical electrical specs and pinout. | Suitable for automotive or outdoor industrial deployments where ambient exceeds +70°C. | Select MAX691AESE+ when operating outside 0°C–70°C; otherwise MAX691ACSE+T offers cost-optimized commercial-grade performance. |
| TPS3823-46DBVR | Single active-low RESET output; 4.63V threshold; no watchdog, CE gating, or battery switchover. | Limited to basic reset supervision; lacks backup power management and memory protection features. | Choose TPS3823-46DBVR only for simple reset-only use cases; MAX691ACSE+T provides integrated functionality unattainable with discrete alternatives. |
Compared with MAX691AESE+, the MAX691ACSE+T trades extended temperature support for lower unit cost in commercial environments, while versus TPS3823-46DBVR it delivers comprehensive supervision (watchdog, CE gating, battery switchover) in a single SO-16 package - reducing BOM count and PCB area.
Availability
MAX691ACSE+T is available at Aetrix Electronics and suitable for industrial controllers, intelligent instruments, and critical μP power monitoring applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX691ACSE+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 and mixed-signal ICs for power, interface, sensing, and timing applications.
The MAX691A family was designed specifically for robust microprocessor supervision in 5V systems - integrating reset generation, watchdog monitoring, battery backup, and memory protection in a single compact package.
FAQ
What is the guaranteed minimum reset threshold voltage for MAX691ACSE+T?
The MAX691ACSE+T has a guaranteed minimum reset threshold voltage of 4.50V over temperature and supply variations, with a typical value of 4.65V and maximum of 4.75V. This specification ensures reliable reset assertion during 5V supply brownouts and is validated for the MAX691A variant per the datasheet's Electrical Characteristics table.
Does MAX691ACSE+T support battery backup with supercapacitors?
Yes, MAX691ACSE+T is explicitly MaxCap® and SuperCap-compatible. Its VBATT input supports direct connection to large-value backup capacitors (e.g., 0.47F), with VBATT-to-VOUT on-resistance ≤30Ω at 2.0V, enabling low-loss switchover and sustained operation during main supply interruption.
Can MAX691ACSE+T generate both active-high and active-low reset signals simultaneously?
Yes, MAX691ACSE+T provides two independent reset outputs: pin 15 (RESET, active-low open-drain) and pin 16 (RESET, active-high open-drain). Both are asserted synchronously when VCC falls below 4.65V and remain coordinated through the 200ms timeout - enabling direct interface with μPs requiring either polarity.
What is the maximum continuous output current supported by MAX691ACSE+T on VOUT?
MAX691ACSE+T supports up to 250mA continuous output current on VOUT when sourced from VCC, with a typical VCC-to-VOUT dropout of 200mV at full load. Exceeding this requires external pass devices, as the internal PMOS switch and parallel diode are rated for 250mA continuous and 1A transient peak.
How does the watchdog function behave when WDI is left unconnected on MAX691ACSE+T?
When WDI is left unconnected on MAX691ACSE+T, an internal 100kΩ-equivalent resistor network biases it to ~1.6V, disabling the watchdog timer. WDO remains high, and no reset pulses are generated - confirming that floating WDI is a documented, safe method to deactivate watchdog functionality per the datasheet's Detailed Description section.
MAX691ACSE+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX691ACSE+T FAQ
1.How can I place an order for MAX691ACSE+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691ACSE+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 MAX691ACSE+T reliable?
The price and inventory of MAX691ACSE+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691ACSE+T is usually 5 days.
3.What payment methods are accepted for MAX691ACSE+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691ACSE+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691ACSE+T?
MAX691ACSE+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691ACSE+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 MAX691ACSE+T?
For technical support, including MAX691ACSE+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691ACSE+T requirements.
6.How does Aetrix verify that MAX691ACSE+T is sourced from the original manufacturer or authorized distributors?
All MAX691ACSE+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 MAX691ACSE+T meets industry standards.
7.What is the process for return or replacement of MAX691ACSE+T?
All MAX691ACSE+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX691ACSE+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 MAX691ACSE+T part is unused and in its original packaging.
Return procedure for MAX691ACSE+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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