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Analog Devices Inc./Maxim Integrated MAX690TCSA+
- Part No.:
- MAX690TCSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690TCSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:176
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Product details
Overview
MAX690TCSA+ from Maxim Integrated is a 3.3V microprocessor supervisory circuit with precision reset threshold (3.075V), 200ms reset timeout, integrated watchdog timer (1.6s), battery-backup switchover, and power-fail warning capability. 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-enabling reliable CMOS RAM retention in portable controllers and embedded systems.
For engineers reviewing the MAX690TCSA+ datasheet, MAX690TCSA+ pinout, MAX690TCSA+ application, or MAX690TCSA+ equivalent, this page delivers verified technical context, exact pin functions, real-world use cases in battery-backed µP systems, and validated alternative parts for 3.0V/3.3V supervisory design.
Technical Context
The MAX690TCSA+ integrates five core functions in a single 8-pin SO package: a precision reset comparator with ±4% threshold tolerance (3.075V nominal), a 1.6s watchdog timer that clears on WDI edge transitions, a battery switchover circuit with 140Ω VBATT-to-VOUT switch and 3Ω VCC-to-VOUT PMOS switch, a power-fail comparator (VPFT = 1.237V, ±10mV hysteresis), and manual reset input with internal 70µA pull-up.
It operates across 0°C to +70°C, supports VCC from 1.0V to 5.5V (guaranteed RESET assertion down to VCC = 1V), draws only 40µA typical VCC supply current, and maintains 1µA battery leakage-making it suitable for low-power, long-life battery-backed applications where supply stability and data retention are critical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 3.075V (VCC falling), ±4% tolerance - ensures reset assertion before 3.3V supply drops below system minimum operating voltage. |
| Reset Timeout Period | 200ms (typical) - guarantees µP remains held in reset long enough for stable power rail recovery after brownout. |
| Watchdog Timeout | 1.6s - detects µP lockup by requiring periodic WDI toggling; prevents uncontrolled system operation. |
| VCC Supply Current | 40µA (typical, VCC < 3.6V) - enables multi-year operation on coin-cell batteries in backup mode. |
| Battery Leakage Current | 0.01–0.5µA - minimizes self-discharge of lithium backup cells, preserving RAM data for years. |
| VBATT Switch Threshold | 2.40V (VCC rising), 25mV hysteresis - initiates battery switchover early enough to maintain VOUT above 2.0V for CMOS RAM retention. |
| Power-Fail Input Threshold | 1.237V ±10mV - provides accurate undervoltage detection for auxiliary supplies via external resistor divider. |
Pinout & Package
MAX690TCSA+ is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package, RoHS-compliant, with 1.27mm pitch and surface-mount footprint per land pattern 90-0096.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | VOUT | Switched output connected to VCC (via 3Ω PMOS) or VBATT (via 140Ω switch); powers CMOS RAM during main supply failure. |
| 2 | VCC | Main 3.0V/3.3V supply input; reset comparator reference; powers internal circuitry. |
| 3 | GND | Ground reference for all analog comparators, digital logic, and power switches. |
| 4 | PFI | Power-fail input; compared to 1.237V internal reference to generate PFO low signal on undervoltage. |
| 5 | PFO | Open-drain power-fail output; asserts low when PFI < 1.237V or VCC < 2.40V - used for interrupt or MR triggering. |
| 6 | WDI | Watchdog input; rising/falling edges clear 1.6s timer; static high/low triggers reset - no disable option. |
| 7 | RESET | Active-low open-drain reset output; asserted low during VCC brownout, watchdog timeout, or MR low. |
| 8 | VBATT | Backup battery input; may exceed VCC (e.g., 3.6V Li cell); automatically connects to VOUT when VCC falls below 2.40V. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout conditions where other supervisors lose functionality. |
| Battery can exceed VCC in normal operation | Supports standard 3.6V lithium coin cells without external diodes or regulators - simplifies backup power design. |
| 200ms reset time delay with temperature stability | Remains within 140–280ms over full operating range - eliminates need for external RC timing components. |
| 40µA VCC supply current (typ) | Reduces load on primary supply in always-on monitoring applications - extends battery life in portable equipment. |
| Integrated power-fail comparator with 10mV hysteresis | Enables reliable detection of secondary supply faults (e.g., 5V rail) using simple resistor dividers - no extra IC required. |
Applications
| Battery-Powered Embedded Controller | Critical µP Power Monitoring |
|---|---|
Use Scenario: Industrial sensor node powered by AA batteries with SRAM-based configuration storage. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, watchdog supervision, and automatic RAM backup switchover to VBATT. Use Value: Prevents firmware corruption during intermittent power loss and preserves calibration data for >10 years using 3.6V lithium cell. |
Use Scenario: Medical infusion pump requiring guaranteed startup sequence and runtime fault detection. IC Role / Device Role / Timing Role: Primary power monitor asserting RESET at 3.075V VCC drop and triggering watchdog reset if motor controller hangs. Use Value: Meets IEC 62304 safety requirements by eliminating undetected µP lockup and ensuring deterministic power-up behavior. |
| Intelligent Instrumentation | Portable Data Logger |
Use Scenario: Handheld multimeter with EEPROM and real-time clock backed by coin cell. IC Role / Device Role / Timing Role: Supplies clean VOUT to RTC and memory during main supply interruption; generates PFO interrupt on AC adapter disconnect. Use Value: Maintains timekeeping accuracy and logging continuity without external power-path management ICs. |
Use Scenario: Environmental logger deployed in remote locations with solar charging and Li-ion backup. IC Role / Device Role / Timing Role: Monitors 3.3V system rail, asserts RESET on solar panel under-voltage, and switches VOUT to battery before RAM data loss. Use Value: Achieves >5-year field deployment with zero data loss events due to precise 2.40V switchover threshold. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704TCSA+ | Identical pinout and reset threshold (3.075V), but adds manual reset (MR) input - MAX690TCSA+ lacks MR. | Required where operator-initiated reset is needed (e.g., field service button); not suitable if MR function must be omitted. | Select MAX704TCSA+ only when manual reset functionality is explicitly required; otherwise MAX690TCSA+ reduces BOM count. |
| MAX802TCSA+ | Tighter reset threshold tolerance (±2% vs. ±4%) and improved PFI accuracy (±2% vs. ±75mV); same 8-pin SO package. | Better suited for high-precision 3.3V systems with tight supply margins (e.g., FPGA configuration circuits). | Choose MAX802TCSA+ for designs demanding higher reset accuracy; MAX690TCSA+ remains optimal for cost-sensitive, general-purpose µP supervision. |
Compared with MAX704TCSA+, MAX690TCSA+ omits MR to reduce complexity and cost; compared with MAX802TCSA+, it trades tighter tolerances for broader compatibility and lower unit price - making it the balanced choice for mainstream 3.3V embedded control.
Availability
MAX690TCSA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instrumentation, and critical µP power monitoring requiring stable component supply across industrial temperature ranges.
Supply support for MAX690TCSA+ 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, communications, and computing markets.
The MAX690 series was designed specifically for 3.0V/3.3V microprocessor systems needing integrated reset, watchdog, battery switchover, and power-fail detection - reducing discrete component count while improving reliability in space-constrained embedded applications.
FAQ
What is the exact reset threshold voltage for MAX690TCSA+?
The MAX690TCSA+ has a nominal reset threshold of 3.075V when VCC is falling, with a tolerance of ±4% (3.00V to 3.15V). This value is guaranteed over the full 0°C to +70°C operating temperature range and ensures reset assertion before the 3.3V supply falls below the minimum required for reliable µP operation. The rising threshold is slightly higher (3.085V typ) due to 10mV internal hysteresis.
Does MAX690TCSA+ include a manual reset input?
No, MAX690TCSA+ does not include a manual reset (MR) input. Unlike the MAX704TCSA+ or MAX806TCSA+, the MAX690TCSA+ pinout omits MR functionality - pin 6 is dedicated to WDI only. This simplifies design where operator-initiated reset is unnecessary and reduces potential noise coupling paths in sensitive measurement systems.
Can MAX690TCSA+ support a 3.6V lithium battery on VBATT while VCC is at 3.3V?
Yes, MAX690TCSA+ explicitly supports VBATT exceeding VCC - including standard 3.6V lithium coin cells - without external diodes or level-shifting. Its internal battery switchover circuit activates when VCC falls below 2.40V, connecting VBATT directly to VOUT through a 140Ω switch, enabling seamless RAM backup even with higher-voltage batteries.
What is the watchdog timeout period for MAX690TCSA+ and how is it cleared?
The MAX690TCSA+ features a fixed 1.6s watchdog timeout period (1.12s to 2.24s over temperature). It is cleared only by a rising or falling edge on the WDI pin - static high or low states will trigger reset. Unlike some variants, the watchdog cannot be disabled; it remains active whenever VCC is valid and RESET is deasserted.
How does MAX690TCSA+ handle power-fail detection for auxiliary supplies?
MAX690TCSA+ uses its PFI input (pin 4) referenced to a precise 1.237V internal bandgap. When an external resistor divider scales a secondary supply (e.g., 5V or –5V rail) to ≤1.237V, the PFO output (pin 5) goes low - signaling undervoltage. This allows monitoring of multiple rails with one IC, and PFO can be wired to MR on compatible parts like MAX704TCSA+ to initiate system reset.
MAX690TCSA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 3.075V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX690TCSA+ FAQ
1.How can I place an order for MAX690TCSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690TCSA+ 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 MAX690TCSA+ reliable?
The price and inventory of MAX690TCSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690TCSA+ is usually 5 days.
3.What payment methods are accepted for MAX690TCSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690TCSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690TCSA+?
MAX690TCSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690TCSA+ 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 MAX690TCSA+?
For technical support, including MAX690TCSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690TCSA+ requirements.
6.How does Aetrix verify that MAX690TCSA+ is sourced from the original manufacturer or authorized distributors?
All MAX690TCSA+ 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 MAX690TCSA+ meets industry standards.
7.What is the process for return or replacement of MAX690TCSA+?
All MAX690TCSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX690TCSA+, 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 MAX690TCSA+ part is unused and in its original packaging.
Return procedure for MAX690TCSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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