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Analog Devices Inc./Maxim Integrated MAX690ACSA
- Part No.:
- MAX690ACSA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX690ACSA.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,974
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Product details
Overview
The MAX690ACSA from Maxim Integrated is a microprocessor supervisory circuit in 8-pin SO package, providing precision reset generation (4.65V threshold), 200ms reset pulse width, 1.6s watchdog timeout, battery-backup switchover, and 1.25V power-fail comparator for +5V systems. It ensures reliable μP startup, brownout recovery, and RAM retention in embedded controllers.
For engineers reviewing the MAX690ACSA datasheet, MAX690ACSA pinout, MAX690ACSA application, or MAX690ACSA equivalent, this device delivers verified reset timing, guaranteed RESET assertion down to VCC = 1V, battery-switching hysteresis of 40mV, and ±2% power-fail accuracy-critical for industrial instrumentation and battery-powered computing.
Technical Context
The MAX690ACSA integrates four independent functional blocks: a precision voltage monitor with 4.65V reset threshold and 40mV hysteresis, a 1.6s watchdog timer cleared by WDI edge transitions, a battery switchover circuit using dual PMOS switches (5Ω for VCC→VOUT, 80Ω for VBATT→VOUT), and a 1.25V reference-based power-fail comparator with 400ns response time.
Its reset generator guarantees logic-low output during power-up until VCC reaches 1V, holds RESET low for 200ms after VCC exceeds 4.65V, and reasserts RESET on any subsequent brownout. In backup mode (VCC < 4.65V and VBATT > VCC + 20mV), quiescent current drops to 50nA while maintaining VOUT regulation from VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±50mV - triggers reset when +5V supply falls below nominal operating level, with 40mV hysteresis to prevent chatter |
| Reset Pulse Width | 200ms typical - provides sufficient hold time for μP initialization and peripheral stabilization |
| Watchdog Timeout | 1.6s ±0.65s - detects software lockup if WDI is not toggled, with 50ns minimum pulse detection capability |
| Supply Current (Active) | 200–350µA - enables low-power operation in always-on monitoring applications |
| Supply Current (Backup) | 50nA - minimizes battery drain during extended power loss, preserving CMOS RAM for months |
| VOUT Switch Resistance | 5Ω (VCC→VOUT), 80Ω (VBATT→VOUT) - limits voltage drop under load while enabling efficient battery switchover |
| Power-Fail Comparator Accuracy | ±2% at TA = +25°C - ensures precise early-warning detection of supply degradation before system failure |
Pinout & Package
MAX690ACSA is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package with standard JEDEC MS-012AC outline, 1.27mm pitch, and RoHS-compliant lead-free finish (S8+2 package code).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC and VBATT based on reset threshold crossing; delivers regulated +5V or battery voltage with <5Ω drop |
| 2 - VCC | +5V main supply input | Primary power source; powers internal circuitry and enables VCC→VOUT conduction above 4.65V |
| 3 - GND | Analog/digital ground reference | Common return path for all internal blocks; must be low-impedance to ensure comparator accuracy |
| 4 - PFI | Power-fail comparator input | Accepts external voltage divider signal; asserts PFO low when input falls below 1.25V reference |
| 5 - PFO | Power-fail open-drain output | Drives µP interrupt line low on undervoltage condition; requires external pull-up resistor |
| 6 - WDI | Watchdog timer input | Edge-sensitive control pin; floating or high-Z state disables watchdog; 50kΩ internal bias to 35% VCC |
| 7 - RESET | Active-low reset output | Guaranteed logic-low from VCC = 1V upward; pulses low for 200ms on power-up, brownout, or watchdog timeout |
| 8 - VBATT | Backup battery input | Connects lithium cell (3.0–3.6V); activates switchover only when VCC < 4.65V and VBATT > VCC + 20mV |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures deterministic reset initiation even during slow-ramp power-up sequences common in battery-backed systems |
| Battery switchover hysteresis | 40mV prevents oscillation during gradual VCC decay, eliminating repeated RAM switching and data corruption |
| Power-fail comparator response time | 400ns enables real-time detection of fast transients on unregulated DC inputs feeding +5V regulators |
| Quiescent current in backup mode | 50nA allows single CR2032 battery to sustain CMOS RAM for >10 years without replacement |
| Internal 1.25V reference tolerance | ±1% over temperature ensures stable PFI trip point across 0°C to +70°C operating range |
Applications
| Battery-Powered Computers and Controllers | Intelligent Instruments |
|---|---|
Use Scenario: Portable data loggers powered by primary alkaline cells with optional lithium backup for memory retention during field deployment. IC Role / Device Role / Timing Role: Supervisory IC providing brownout reset, watchdog supervision, and seamless RAM switchover to VBATT upon main supply collapse. Use Value: Prevents firmware corruption and preserves calibration data during intermittent power loss, extending field service life without user intervention. |
Use Scenario: Benchtop multimeters and oscilloscopes requiring nonvolatile storage of user settings and measurement history across AC mains interruptions. IC Role / Device Role / Timing Role: Reset generator and power-fail detector that triggers controlled shutdown via PFO interrupt and maintains SRAM contents via VOUT switchover. Use Value: Eliminates need for external EEPROM writes during power loss, reducing write-cycle wear and enabling instant resume after restoration. |
| Critical μP Power Monitoring | Industrial Process Controllers |
Use Scenario: PLC modules monitoring 24VDC field bus supplies where undervoltage events indicate wiring faults or sensor failures. IC Role / Device Role / Timing Role: Precision voltage monitor asserting RESET within 2µs of VCC dip below 4.65V, with 200ms hold time for safe state capture. Use Value: Enables deterministic fault isolation by halting μP execution before corrupted I/O states propagate to actuators or safety circuits. |
Use Scenario: Distributed I/O nodes in factory automation networks powered from centralized 5V rails subject to cable voltage drop and transient noise. IC Role / Device Role / Timing Role: Dual-function supervisor combining reset generation and PFI-based early warning to initiate graceful degradation before hard reset. Use Value: Reduces unplanned downtime by allowing host controller to log fault conditions and initiate diagnostics prior to full system reset. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX802LCSA | Identical pinout and function; same 4.65V reset threshold and 200ms pulse width; guaranteed ±2% power-fail accuracy | No functional difference; MAX802LCSA is direct replacement with identical qualification and test flow | Select MAX802LCSA when requiring documented ±2% PFI accuracy over full temperature range |
| MAX706RCSA | 2.63V reset threshold, no battery switchover, no PFI/PFO, but adds manual reset input and watchdog output | Suitable for 3.3V systems or designs needing manual reset override; lacks backup power management | Choose MAX706RCSA only for 3.3V μP systems without battery backup requirements |
Compared with MAX802LCSA, MAX690ACSA offers identical functionality and performance but may differ in production lot traceability and long-term availability; versus MAX706RCSA, it supports 5V systems and battery retention but omits manual reset-making it unsuitable for applications requiring operator-initiated reset.
Availability
MAX690ACSA is available at Aetrix Electronics and suitable for battery-powered computers and controllers, intelligent instruments, critical μP power monitoring, industrial process controllers, and portable medical devices requiring stable component supply across extended product lifecycles.
Supply support for MAX690ACSA 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 analog and mixed-signal ICs for power management, sensing, and interface applications.
The MAX690A family was designed specifically for robust microprocessor supervision in industrial and commercial systems, integrating reset, watchdog, battery switchover, and power-fail detection in a single 8-pin package.
FAQ
What is the guaranteed minimum VCC level at which MAX690ACSA asserts RESET?
The MAX690ACSA guarantees RESET assertion down to VCC = 1.0V, ensuring reliable reset initiation even during slow-ramp or weak-supply power-up conditions. This specification is validated across the full 0°C to +70°C operating temperature range and applies to all MAX690ACSA units regardless of manufacturing lot. The internal reset generator remains active and functional at this low voltage, making MAX690ACSA suitable for battery-backed systems where supply voltage may sag significantly before stabilization.
Does MAX690ACSA support active-high reset outputs?
No, MAX690ACSA provides only an active-low RESET output (pin 7). The active-high RESET variant is implemented in the MAX805L family (e.g., MAX805LCSA), which is a separate part number with different pin mapping and output polarity. MAX690ACSA's RESET output is guaranteed to remain logic-low while VCC is below 4.65V and for 200ms after VCC rises above that threshold. Attempting to use MAX690ACSA in place of an active-high reset device will result in incorrect μP behavior unless external inversion logic is added.
How does the battery switchover hysteresis work in MAX690ACSA?
MAX690ACSA implements 40mV hysteresis in its battery switchover circuit: VBATT connects to VOUT when VCC falls below 4.65V and VBATT exceeds VCC by at least 20mV; VOUT reconnects to VCC only when VCC rises 20mV above VBATT. This prevents rapid toggling during slow VCC decay near the threshold. The hysteresis is achieved through internal comparator design and requires no external components. It ensures stable RAM power delivery during marginal supply conditions and eliminates repeated switching that could corrupt memory contents.
Can MAX690ACSA monitor negative supply rails?
Yes, MAX690ACSA's PFI input can monitor negative voltages using an external resistor network as shown in Figure 7 of the datasheet. By referencing PFI to ground and applying a scaled version of the negative rail through resistive dividers, the internal 1.25V comparator detects when the magnitude of the negative supply degrades. Accuracy depends on resistor tolerance and PFI input current (≤25nA), so precision metal-film resistors are recommended. This configuration is commonly used to supervise –5V or –12V rails in legacy instrumentation systems.
What is the maximum allowable backup battery voltage for MAX690ACSA?
The maximum allowable backup battery voltage for MAX690ACSA is 4.80V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1 in Figure 3) when VCC approaches the reset threshold, causing unintended current flow from VBATT to VCC and potential latch-up. Lithium coin cells (3.0–3.6V) and supercapacitors charged to ≤4.80V are safe; higher-voltage sources require series diodes or regulators to comply. This limit applies strictly to MAX690ACSA and differs from MAX692A/MAX802M (4.55V max).
MAX690ACSA 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:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX690ACSA FAQ
1.How can I place an order for MAX690ACSA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690ACSA 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 MAX690ACSA reliable?
The price and inventory of MAX690ACSA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690ACSA is usually 5 days.
3.What payment methods are accepted for MAX690ACSA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690ACSA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690ACSA?
MAX690ACSA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690ACSA 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 MAX690ACSA?
For technical support, including MAX690ACSA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690ACSA requirements.
6.How does Aetrix verify that MAX690ACSA is sourced from the original manufacturer or authorized distributors?
All MAX690ACSA 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 MAX690ACSA meets industry standards.
7.What is the process for return or replacement of MAX690ACSA?
All MAX690ACSA units undergo pre-shipment inspection (PSI). If there is an issue with MAX690ACSA, 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 MAX690ACSA part is unused and in its original packaging.
Return procedure for MAX690ACSA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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