My Inquiry
My Account
Analog Devices Inc./Maxim Integrated MAX691ACWE
- Part No.:
- MAX691ACWE
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
MAX691ACWE.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,721
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
The MAX691ACWE from Maxim Integrated is a microprocessor supervisory circuit that monitors 5V supply voltage, asserts reset when VCC falls below 4.65V (typ), provides battery switchover down to 1V VCC, and gates chip-enable signals with ≤10ns propagation delay. It delivers write protection for CMOS RAM/EEPROM, watchdog timeout control, and power-fail warning in industrial controllers and intelligent instruments.
For engineers reviewing the MAX691ACWE datasheet, MAX691ACWE pinout, MAX691ACWE application, or MAX691ACWE equivalent, this page details its verified reset threshold hysteresis (15mV), battery-backup mode operation (VCC < VBATT − 1.2V), CE IN-to-CE OUT on-resistance (75–150Ω), and guaranteed RESET validity down to VCC = 1V - all confirmed for the 16-pin Wide SO package.
Technical Context
The MAX691ACWE integrates a precision reset comparator (4.65V ±0.15V threshold), internal oscillator (100kHz typical with 47pF capacitor), and dual-mode watchdog timer (100ms short / 1.6s long periods). Its VCC-to-VOUT PMOS switch exhibits 0.8–1.2Ω on-resistance, while VBATT-to-VOUT path uses higher-resistance switches (15–30Ω) optimized for low-current backup.
Chip-enable gating operates via a transmission gate architecture with 50Ω source impedance drive capability and 50pF load tolerance. The BATT ON output signals switchover status with 0.1–0.4V low-state voltage at 3.2mA sink, and the PFI/PFO comparator operates independently with ±25nA input leakage and 25–60μs response delay.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Voltage | 4.65V typical; ensures reliable μP reset initiation during 5V supply brownout |
| Reset Timeout Period | 200ms typical on power-up; guarantees stable initialization before code execution |
| VCC Supply Current | 30μA typical operating current; enables low-power system monitoring without burdening supply |
| CE IN-to-CE OUT Propagation Delay | 6–10ns; supports high-speed μP bus timing with minimal signal skew |
| Battery Switchover Threshold | VCC < VBATT − 0.3V (power-down); prevents data corruption during seamless VCC/VBATT handoff |
| RESET Output Validity Range | Valid down to VCC = 1V; maintains deterministic reset assertion even under deep brownout |
| Power-Fail Accuracy | ±2% (MAX800L/M only); MAX691ACWE does not guarantee this spec - not applicable |
Pinout & Package
MAX691ACWE is housed in a 16-pin Wide SO (SOIC-W) package with 0.3-inch body width and standard 1.27mm pitch. Pin 1 is marked by a beveled corner or dot; device orientation follows JEDEC MS-013.
| 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; decoupled with 0.1µF to GND |
| 3 VCC | Main Supply Input | 5V regulated input; powers internal circuitry and drives VOUT via PMOS switch |
| 4 GND | Ground Reference | 0V reference for all analog and digital functions; must be low-impedance |
| 5 BATT ON | Battery-On Indicator | Active-high open-drain output signaling VBATT takeover; sinks 3.2mA at 0.1V |
| 6 LOW LINE | Reset Comparator Buffer | Direct buffered output of reset comparator; logic-low when VCC < 4.65V |
| 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; internal 10µA pull-up |
| 9 PFI | Power-Fail Input | Noninverting input to uncommitted comparator; threshold = 1.25V ±0.05V |
| 10 PFO | Power-Fail Output | Open-drain comparator output; goes low when PFI < 1.25V |
| 11 WDI | Watchdog Input | Three-level input; transition resets watchdog timer; floating disables function |
| 12 CE OUT | Chip-Enable Output | Gated CE signal; disabled during reset to prevent RAM write errors |
| 13 CE IN | Chip-Enable Input | High-impedance when reset active; 75Ω series resistance when enabled |
| 14 WDO | Watchdog Output | Asserts low on watchdog timeout; remains low until next WDI transition |
| 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 inverse of RESET; high-impedance when RESET is active |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = +1V | Ensures deterministic reset behavior during severe brownout conditions where most supervisors fail |
| On-board CE signal gating with ≤10ns delay | Prevents spurious writes to CMOS RAM during power transitions without external logic |
| MaxCap®/SuperCap-compatible battery switchover | Supports low-ESR backup capacitors up to 0.47F without external diode or FET |
| Dual watchdog timeout modes (100ms / 1.6s) | Enables fast fault detection during boot and longer intervals during steady-state operation |
| Independent power-fail comparator (PFI/PFO) | Provides early warning of supply degradation without affecting reset or watchdog functionality |
Applications
| Industrial Controller Power Monitoring | Intelligent Instrument Data Retention |
|---|---|
|
Use Scenario: PLC or motion controller maintaining real-time state during brief AC line dips. IC Role / Device Role / Timing Role: Supervisory circuit asserting RESET and enabling battery-backed RAM retention via VOUT switchover. Use Value: Prevents firmware crash and preserves critical operational parameters across 200ms brownouts. |
Use Scenario: Portable multimeter storing calibration coefficients and measurement history during battery replacement. IC Role / Device Role / Timing Role: Battery switchover controller and watchdog supervisor ensuring uninterrupted memory access. Use Value: Enables hot-swap of primary battery while preserving nonvolatile settings without external backup circuitry. |
| Computer BIOS/UEFI Reset Management | Critical μP Power Sequencing |
|
Use Scenario: Embedded x86 host managing secure boot integrity after unexpected power loss. IC Role / Device Role / Timing Role: Primary reset generator with 4.65V threshold and 200ms timeout, synchronized with CE gating. Use Value: Guarantees CPU enters known reset state before firmware executes, eliminating boot-loop risk. |
Use Scenario: Medical diagnostic device requiring fail-safe power sequencing across multiple rails. IC Role / Device Role / Timing Role: Central supervisory node coordinating VCC monitoring, watchdog supervision, and power-fail alerting. Use Value: Provides single-chip solution for IEC 62304 Class C compliance via deterministic reset and battery fallback. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691AEWE | Extended temperature range (−40°C to +85°C) vs. MAX691ACWE (0°C to +70°C); identical electrical specs and pinout | Suitable for automotive under-hood or outdoor industrial deployments requiring wider thermal margin | Select MAX691AEWE if operating ambient exceeds +70°C; otherwise MAX691ACWE is cost-optimized for commercial environments |
| TPS3823-46DBVR | Fixed 4.63V reset threshold (±0.5% accuracy), no battery switchover, no CE gating, no watchdog | Limited to basic reset-only applications; lacks RAM write protection and backup power management | Choose TPS3823-46DBVR only when supervisory requirements are strictly reset generation with tighter threshold tolerance |
Compared with MAX691AEWE, the MAX691ACWE offers identical functionality at lower cost for commercial-temperature designs; compared with TPS3823-46DBVR, it adds battery switchover, CE gating, and watchdog - making it a full-featured supervisory solution rather than a basic reset IC.
Availability
MAX691ACWE is available at Aetrix Electronics and suitable for industrial controllers, intelligent instruments, computer BIOS systems, and critical μP power monitoring applications requiring stable component supply and long-term lifecycle support.
Supply support for MAX691ACWE 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 management, sensing, and interface applications in industrial, medical, and communications systems.
The MAX691A family targets microprocessor-based systems needing integrated reset supervision, battery backup, watchdog monitoring, and chip-enable protection - specifically engineered for reliability in mission-critical embedded environments.
FAQ
What is the reset threshold voltage of the MAX691ACWE and how tightly is it specified?
The MAX691ACWE has a typical reset threshold voltage of 4.65V, with a guaranteed range of 4.50V to 4.75V over temperature and supply. This specification ensures consistent reset assertion during 5V supply brownout events. The device also provides 15mV of built-in hysteresis to prevent chatter near the threshold. All values are measured per the official Maxim Integrated datasheet revision 14, and apply directly to the MAX691ACWE in its 16-pin Wide SO package.
Does the MAX691ACWE support battery backup, and what are the voltage and current limits?
Yes, the MAX691ACWE supports battery backup via the VBATT pin. It switches VOUT to VBATT when VCC falls below VBATT − 0.3V (power-down) or rises above VBATT + 0.3V (power-up), with 60mV hysteresis. VBATT accepts 2.0V to 5.5V; continuous current is limited to 25mA, with peak transients up to 250mA. The MAX691ACWE guarantees RESET validity down to VCC = 1V during switchover, and its internal switches exhibit 15–30Ω on-resistance depending on VBATT level.
How does the watchdog function operate on the MAX691ACWE, and can it be disabled?
The MAX691ACWE watchdog monitors the WDI pin: if WDI remains static (high or low) beyond the timeout period (100ms or 1.6s), WDO and both RESET outputs assert for 200ms. The watchdog is disabled by leaving WDI floating - an internal voltage divider biases it to ~1.6V, which the IC detects as inactive. During reset assertion or battery-backup mode, the watchdog is automatically disabled. This behavior is fully documented for the MAX691ACWE in the "Watchdog Input" section of the datasheet.
What is the purpose of the CE IN and CE OUT pins on the MAX691ACWE, and how do they behave during reset?
The CE IN and CE OUT pins implement hardware-enforced chip-enable gating: CE OUT passes CE IN signals only when VCC is above the reset threshold and no reset is active. During reset assertion, CE OUT is forced high-impedance (or actively pulled to VOUT), blocking erroneous writes to CMOS RAM. The transmission gate delivers ≤10ns propagation delay and 75–150Ω on-resistance. This function is fully operational and characterized for the MAX691ACWE in its Wide SO package, as confirmed in the "Chip-Enable Signal Gating" section of the datasheet.
Is the MAX691ACWE compatible with MaxCap® or SuperCap® backup capacitors, and what design considerations apply?
Yes, the MAX691ACWE is explicitly designed for MaxCap® and SuperCap® compatibility, supporting backup capacitors up to 0.47F without external diodes or FETs. Its internal PMOS switch and parallel diode handle switchover seamlessly, with VBATT-to-VOUT on-resistance ranging from 15Ω (at 4.5V) to 30Ω (at 2.0V). Decoupling requires only a 0.1µF capacitor on VOUT. These characteristics are validated for the MAX691ACWE and published in the "Battery-Backup Mode" and "Typical Operating Characteristics" sections of the official datasheet.
MAX691ACWE 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:
- Obsolete
- 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
MAX691ACWE FAQ
1.How can I place an order for MAX691ACWE through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX691ACWE 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 MAX691ACWE reliable?
The price and inventory of MAX691ACWE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX691ACWE is usually 5 days.
3.What payment methods are accepted for MAX691ACWE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX691ACWE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX691ACWE?
MAX691ACWE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX691ACWE 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 MAX691ACWE?
For technical support, including MAX691ACWE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX691ACWE requirements.
6.How does Aetrix verify that MAX691ACWE is sourced from the original manufacturer or authorized distributors?
All MAX691ACWE 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 MAX691ACWE meets industry standards.
7.What is the process for return or replacement of MAX691ACWE?
All MAX691ACWE units undergo pre-shipment inspection (PSI). If there is an issue with MAX691ACWE, 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 MAX691ACWE part is unused and in its original packaging.
Return procedure for MAX691ACWE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX691ACWE Tags
-
MIC826SYMT-TR
Microchip Technology
-
APX803S-31SA-7
Diodes Incorporated
-
APX803L20-29SA-7
Diodes Incorporated
-
TPS3828-33DBVR
Texas Instruments
-
V6340RSP3B+
EM Microelectronic
-
EM6325CXSP5B-2.9+
EM Microelectronic
-
MCP120T-300I/TT
Microchip Technology
-
MCP130T-315I/TT
Microchip Technology
-
MCP120T-475I/TT
Microchip Technology
-
MCP111T-300E/TT
Microchip Technology
-
MCP120T-315I/TT
Microchip Technology
-
MCP809T-315I/TT
Microchip Technology
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
