My Inquiry
My Account
Analog Devices Inc./Maxim Integrated MAX690RESA+T
- Part No.:
- MAX690RESA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690RESA+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,915
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
MAX690RESA+T from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with precision reset threshold of 2.625V (R-suffix), 200ms reset timeout, watchdog timer (1.6s), battery-backup switchover, and power-fail monitoring. It monitors VCC supply integrity, asserts active-low RESET during brownout or watchdog timeout, and switches VOUT to VBATT when VCC drops below 2.40V - used in battery-backed embedded controllers requiring reliable power-up/power-down sequencing.
For engineers reviewing the MAX690RESA+T datasheet, MAX690RESA+T pinout, MAX690RESA+T application, or MAX690RESA+T equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, ±4% reset threshold accuracy, 40µA VCC supply current, battery-leakage current <1µA, and compatibility with lithium coin-cell backup sources in portable instrumentation and critical µP systems.
Technical Context
The MAX690RESA+T integrates a precision voltage comparator for reset generation, a 1.6s watchdog timer with edge-triggered clear, a dual-path battery switchover circuit (VBATT-to-VOUT via 140Ω switch, VCC-to-VOUT via 3Ω PMOS), and an independent power-fail comparator (VPFT = 1.237V ±20mV). Its reset logic guarantees low output for VCC < 2.625V and holds RESET low for 140–280ms after VCC recovery.
It operates across –40°C to +85°C (E-grade), supports VCC from 2.72V to 5.5V (R-suffix range), tolerates VBATT up to 6.0V, and features MR input with 70µA internal pull-up. The device lacks watchdog disable capability and requires no external components for basic supervision - all functions are internally trimmed and temperature-compensated.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold (VCC falling) | 2.55V to 2.70V (nominal 2.625V); ensures reset assertion before 3.0V system drops below 2.59V, accommodating 14% tolerance |
| Reset Timeout Period | 140–280ms; provides sufficient hold time for µP initialization after power stabilization |
| VCC Supply Current | 40–65µA (VCC < 3.6V); enables ultra-low-power operation in always-on battery-backed systems |
| Battery Supply Current | 0.4–1µA; minimizes drain on 3.6V lithium cells during extended backup mode |
| Watchdog Timeout | 1.12–2.24s (typ 1.6s); detects µP lockup without requiring software intervention |
| Power-Fail Input Threshold | 1.187–1.287V (VPFT); allows accurate undervoltage detection on auxiliary rails via resistor divider |
| VBATT-to-VOUT On-Resistance | 140Ω (typ); limits voltage drop during RAM backup, supporting >2.0V retention under load |
Pinout & Package
MAX690RESA+T is housed in an 8-pin SOIC package (SO) with standard 150mil width and RoHS-compliant lead-free finish (+T suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω NMOS) based on VCC/VBATT comparison; must be decoupled with 0.1µF capacitor |
| VCC | Main supply input | Accepts 2.72V–5.5V; powers internal circuitry and drives VOUT when above reset threshold; absolute max 6.0V |
| GND | Ground reference | Common return for VCC, VBATT, and all logic; substrate tied to higher of VCC/VBATT - must remain floating in hybrid designs |
| PFI | Power-fail input | Compares against 1.237V reference; asserts PFO low when input falls below VPFT or VCC drops below 2.40V; connect to GND if unused |
| PFO | Power-fail open-drain output | Active-low signal indicating supply failure or brownout; can drive MR on MAX704/MAX806 to trigger reset |
| WDI | Watchdog input | Edge-sensitive (rising/falling); clears 1.6s timer on transition; tied high/low causes periodic reset; no disable option |
| RESET | Active-low reset output | Guaranteed low for VCC < 2.625V; held low 200ms after VCC rise/MR release/watchdog timeout; drives µP reset pin directly |
| VBATT | Backup-battery input | Accepts up to 6.0V; may exceed VCC; connects to VOUT during brownout; connect to VCC if no battery used |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout, critical for data retention in volatile memory systems |
| Battery-backup switchover at 2.40V (VSW) | Triggers before VOUT drops below 2.0V, preserving CMOS RAM data integrity without premature battery engagement |
| 200ms reset timeout with 10mV hysteresis | Prevents oscillation during slow-rising VCC while ensuring µP completes power-on self-test before release |
| 40µA typical VCC supply current | Extends operational life of primary batteries in portable equipment where µP remains in sleep mode for extended periods |
| Independent power-fail comparator | Enables monitoring of secondary supplies (e.g., analog rails) without affecting reset timing or battery switching behavior |
Applications
| Battery-Powered Embedded Controller | Critical µP Power Monitoring |
|---|---|
Use Scenario: Industrial sensor node powered by 3.0V Li-SOCl₂ battery with SRAM-based firmware storage. IC Role / Device Role / Timing Role: Supervisory IC asserting RESET during battery depletion, enabling graceful shutdown and RAM save before VCC collapse. Use Value: Prevents corrupted firmware writes by holding µP in reset until VCC stabilizes above 2.625V or battery is replaced. |
Use Scenario: Medical infusion pump requiring deterministic boot sequence and continuous power-fail detection. IC Role / Device Role / Timing Role: Primary reset generator and watchdog enforcer; monitors main 3.3V rail and triggers hard reset on µP hang or undervoltage. Use Value: Meets IEC 62304 safety requirements by guaranteeing reset assertion down to VCC = 1V and eliminating single-point failure modes. |
| Intelligent Instrumentation | Portable Test Equipment |
Use Scenario: Handheld multimeter with real-time clock and configuration EEPROM backed by coin cell. IC Role / Device Role / Timing Role: Battery switchover controller maintaining VOUT >2.0V to preserve RTC and EEPROM contents during AC adapter removal. Use Value: Eliminates need for external diode-or circuitry; 140Ω VBATT-to-VOUT switch ensures <50mV dropout at 1mA load. |
Use Scenario: Portable oscilloscope using SuperCap for brief AC outage ride-through. IC Role / Device Role / Timing Role: Switchover manager connecting SuperCap to VOUT when VCC falls below 2.40V; resets µP if SuperCap voltage depletes. Use Value: Enables seamless transition to backup power without µP intervention; supports >10-second hold-up time with 0.47F SuperCap. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704RESA+ | Identical reset threshold (2.625V), but adds manual reset (MR) input with 70µA pull-up; no WDI or PFI/PFO | Lacks watchdog and power-fail monitoring; suited for simpler reset-only systems without brownout recovery logic | Select MAX704RESA+ only when watchdog and auxiliary supply monitoring are unnecessary and MR-driven reset is preferred |
| MAX805RESA+ | Same R-suffix threshold (2.625V), tighter ±2% reset tolerance, active-high open-drain RESET, no MR input | Designed for µPs with bidirectional reset pins; requires external pull-up; no manual reset or watchdog capability | Choose MAX805RESA+ for systems needing precise reset timing and compatibility with bidirectional reset I/O, e.g., Motorola 68HC11 |
Compared with MAX704RESA+ and MAX805RESA+, the MAX690RESA+ uniquely combines reset supervision, watchdog timeout, battery switchover, and power-fail detection in a single 8-pin SOIC - making it optimal for space-constrained, feature-rich embedded systems where reliability across multiple fault conditions is mandatory.
Availability
MAX690RESA+T is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instrumentation, critical µP power monitoring, portable test equipment, and embedded controllers requiring stable component supply across industrial temperature ranges.
Supply support for MAX690RESA+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) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.
The MAX690 series was developed specifically for 3.0V/3.3V microprocessor systems requiring integrated reset, watchdog, battery switchover, and power-fail monitoring - targeting portable, battery-backed, and safety-critical embedded platforms.
FAQ
What is the exact reset threshold voltage for MAX690RESA+T?
The MAX690RESA+T has a nominal reset threshold of 2.625V (R-suffix), with guaranteed range of 2.55V to 2.70V for VCC falling. This value is specified at temperature extremes and ensures reset assertion before a 3.0V system drops below 2.59V, aligning with 14% system tolerance requirements. The threshold exhibits 10mV typical hysteresis to prevent chatter during slow VCC transitions.
Does MAX690RESA+T support battery-backup operation with lithium coin cells?
Yes, MAX690RESA+T fully supports lithium coin-cell backup (e.g., CR2032, 3.6V) via the VBATT pin. It automatically switches VOUT from VCC to VBATT when VCC falls below 2.40V (VSW), and maintains VOUT >2.0V under 1mA load using its 140Ω internal switch. Battery leakage is limited to <1µA, enabling multi-year backup life in low-duty-cycle applications.
Can the watchdog timer in MAX690RESA+T be disabled?
No, the watchdog timer in MAX690RESA+T cannot be disabled. It is permanently enabled and clears only on rising or falling edges at the WDI pin or during RESET assertion. If WDI remains static (high or low) for longer than 1.6s (1.12–2.24s range), the timer expires and forces a reset pulse. This design ensures fail-safe µP supervision without software dependency.
What is the function of the PFI and PFO pins on MAX690RESA+T?
The PFI (Power-Fail Input) pin compares an external voltage against a 1.237V internal reference. When PFI falls below this threshold - or when VCC drops below 2.40V - the PFO (Power-Fail Output) pin goes low. PFO is an open-drain output that can signal supply degradation to the µP or trigger reset via MR on compatible devices like MAX704RESA+. PFI must be grounded if unused.
Is MAX690RESA+T compatible with 5V systems?
No, MAX690RESA+T is designed exclusively for 3.0V/3.3V systems. Its reset threshold (2.625V) and operating VCC range (2.72V to 5.5V) are optimized for low-voltage µPs; using it in pure 5V systems risks improper reset timing and reduced noise margin. For 5V applications, select the MAX690C/D/E variants with T/S/R suffixes matched to 5V supply tolerances, or consider the MAX706/MAX708 families.
MAX690RESA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-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:
- 2.625V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX690RESA+T FAQ
1.How can I place an order for MAX690RESA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690RESA+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 MAX690RESA+T reliable?
The price and inventory of MAX690RESA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690RESA+T is usually 5 days.
3.What payment methods are accepted for MAX690RESA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690RESA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690RESA+T?
MAX690RESA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690RESA+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 MAX690RESA+T?
For technical support, including MAX690RESA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690RESA+T requirements.
6.How does Aetrix verify that MAX690RESA+T is sourced from the original manufacturer or authorized distributors?
All MAX690RESA+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 MAX690RESA+T meets industry standards.
7.What is the process for return or replacement of MAX690RESA+T?
All MAX690RESA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX690RESA+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 MAX690RESA+T part is unused and in its original packaging.
Return procedure for MAX690RESA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX690RESA+T 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…
