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Analog Devices Inc./Maxim Integrated MAX690RCPA
- Part No.:
- MAX690RCPA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX690RCPA.pdf
- Description:
- IC SUPERVISOR MAX690 MPU
- Quantity:
- Payment:
- Shipping:
Inventory:1,776
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Product details
Overview
MAX690RCPA from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-low RESET output, 2.625V reset threshold (R-suffix), 200ms reset timeout, watchdog timer (1.6s), and battery-backup switchover for CMOS RAM retention. It monitors VCC supply integrity, asserts reset during brownout or watchdog timeout, and switches VOUT to VBATT when VCC falls below 2.40V - used in embedded controllers and portable equipment requiring reliable power-up/power-down sequencing.
For engineers reviewing the MAX690RCPA datasheet, MAX690RCPA pinout, MAX690RCPA application, or MAX690RCPA equivalent, key selection criteria include its guaranteed RESET assertion down to VCC = 1V, ±4% reset threshold accuracy, 40µA VCC supply current, and support for lithium battery backup exceeding VCC in normal operation.
Technical Context
The MAX690RCPA integrates a precision reset comparator with 2.625V nominal falling-threshold (±4% tolerance), a 1.6s watchdog timer cleared by WDI transitions, and a dual-path battery switchover circuit using PMOS switches (3Ω VCC-to-VOUT, 140Ω VBATT-to-VOUT). Its PFI input enables external power-fail detection at 1.237V with 10mV hysteresis.
It operates across 0°C to +70°C, supports VCC from 2.72V to 5.5V (R-suffix), and guarantees RESET low for VCC < 2.55V while maintaining valid logic levels down to VCC = 1V. The device uses an internal 70µA pull-up on MR and features open-drain PFO with ±75mV power-fail comparator accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V (nominal, falling), ±4% tolerance - ensures reset triggers before VCC drops below 2.55V in 3.0V systems with ±10% supply tolerance. |
| Reset Timeout Period | 200ms (typical) - holds µP in reset long enough for stable clock and supply settling after power-up or brownout recovery. |
| Watchdog Timeout | 1.6s (typical) - detects µP lockup if WDI remains static; cleared on any edge transition, not disableable. |
| VCC Supply Current | 40µA (typical, VCC < 3.6V) - enables ultra-low-power operation in battery-backed systems without compromising supervision reliability. |
| Battery Leakage Current | 0.01–0.5µA (max) - minimizes self-discharge of backup lithium cells during extended standby periods. |
| VBATT-to-VOUT On-Resistance | 140Ω (typical) - limits voltage drop under 1mA load, preserving >2.0V at VOUT for reliable CMOS RAM data retention. |
| Power-Fail Threshold Accuracy | ±75mV - provides precise undervoltage warning for auxiliary supplies via PFI input referenced to 1.237V. |
Pinout & Package
MAX690RCPA is housed in an 8-pin plastic DIP (PDIP) package with 0.300" wide body and through-hole mounting. Pin spacing is 0.100", lead finish is leaded (Pb) unless specified with '+' suffix.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | CMOS RAM supply output | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω PMOS); maintains RAM power during VCC brownout. |
| 2 - VCC | Main system supply input | Accepts 2.72V–5.5V; powers internal circuitry and sources VOUT when above reset threshold and switch threshold (2.40V). |
| 3 - GND | Ground reference | Common return for all analog and digital functions; substrate tied to higher of VCC/VBATT, must be floated in hybrid designs. |
| 4 - PFI | Power-fail input | Monitors external supply via resistor divider; asserts PFO low when voltage falls below 1.237V ±75mV. |
| 5 - PFO | Power-fail open-drain output | Active-low signal indicating PFI undervoltage or VCC < 2.40V; can drive MR on compatible parts (e.g., MAX704) for cascaded reset. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); resets watchdog timer every transition; tied high/low causes 1.6s timeout and reset assertion. |
| 7 - RESET | Active-low reset output | Push-pull, guaranteed low for VCC < 2.55V; stays low 200ms after VCC rises above threshold or MR release. |
| 8 - VBATT | Backup battery input | Accepts 3.6V lithium cell; may exceed VCC; connects to VOUT when VCC < 2.40V or < 1.75V (typ), enabling seamless switchover. |
Key Features
| Feature | Design Value |
|---|---|
| Battery-backup switchover | Automatic VOUT switching to VBATT at VCC = 2.40V (VSW), with 25mV hysteresis - prevents oscillation and extends battery life. |
| Guaranteed RESET assertion | Valid down to VCC = 1V - ensures µP remains held in reset even during deep brownout conditions where other supervisors fail. |
| Low-quiescent-current design | 40µA VCC supply current (typ) and 0.4–1µA VBATT current - enables multi-year operation on coin-cell batteries. |
| Integrated watchdog timer | 1.6s timeout with edge-triggered clear - eliminates need for external timing components and prevents false resets from noise. |
| Power-fail comparator independence | Dedicated PFI/PFO path with 1.237V reference and ±75mV accuracy - allows monitoring of secondary supplies without affecting reset behavior. |
Applications
| Battery-Powered Embedded Controller | Portable Medical Instrument |
|---|---|
Use Scenario: A handheld glucose meter uses a 3.0V supply and CR2032 lithium battery for memory retention during battery replacement. IC Role / Device Role / Timing Role: MAX690RCPA monitors VCC, asserts RESET during power-up/brownout, and switches VOUT to VBATT when VCC drops below 2.40V to preserve calibration data in CMOS RAM. Use Value: Ensures zero data loss during battery swap and guarantees µP reset until VCC stabilizes above 2.55V - meeting IEC 60601-1 reliability requirements. |
Use Scenario: A portable ECG monitor operates from rechargeable Li-ion (3.6V) and requires nonvolatile memory retention during charging interruptions. IC Role / Device Role / Timing Role: MAX690RCPA serves as primary power supervisor: its 2.625V reset threshold matches 3.0V logic rails, while VBATT > VCC capability allows direct connection to 3.6V battery without level-shifting. Use Value: Eliminates external diode OR-ing and reduces BOM count by integrating switchover, reset, and watchdog - critical for space-constrained PCB layouts. |
| Industrial Data Logger | Smart Meter Communication Module |
Use Scenario: A temperature/humidity logger deployed in remote locations uses a 3.3V supply and supercapacitor backup for short-term power loss. IC Role / Device Role / Timing Role: MAX690RCPA's 200ms reset timeout ensures clean µP initialization after capacitor discharge, while PFI monitors auxiliary 5V rail for communication subsystem health. Use Value: PFO output drives interrupt line to µP, enabling real-time fault logging; ±4% reset accuracy prevents spurious resets during marginal 3.3V supply conditions. |
Use Scenario: A PLC-integrated smart meter employs isolated RS-485 communication and requires deterministic reset behavior during grid voltage sags. IC Role / Device Role / Timing Role: MAX690RCPA provides synchronized reset to main µP and communication ASIC; WDI monitors UART activity to detect firmware hangs in modem stack. Use Value: 1.6s watchdog timeout aligns with Modbus RTU frame timing; guaranteed RESET assertion to 1V prevents latch-up during 100ms dips to 2.2V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690SCPA | 2.925V reset threshold (S-suffix), same package and pinout; ±4% tolerance, identical watchdog and switchover specs. | Designed for 3.3V ±10% supplies; asserts reset later than MAX690RCPA - unsuitable where early brownout detection is required at 2.6V. | Select MAX690SCPA only if system VCC minimum is ≥2.85V and earlier reset assertion (e.g., at 2.55V) is unnecessary. |
| MAX706RCSA | SO-8 package (not PDIP), no watchdog timer, 2.63V reset threshold, 1.6µA max VBATT current - lower battery drain but lacks WDI functionality. | Targeted at cost-sensitive, non-watchdog applications; missing battery switchover control logic - requires external MOSFET for RAM backup. | Choose MAX706RCSA only when watchdog is unused and SO-8 footprint is preferred; MAX690RCPA remains superior for integrated RAM backup + watchdog. |
Compared with MAX690SCPA and MAX706RCSA, the MAX690RCPA uniquely combines 2.625V precision reset, integrated 1.6s watchdog, and autonomous battery switchover in a PDIP package - making it optimal for legacy industrial designs requiring early brownout response and zero-additional-component RAM backup.
Availability
MAX690RCPA is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, and intelligent instruments requiring stable component supply with long-term lifecycle support and traceable sourcing.
Supply support for MAX690RCPA 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, automotive, and communications markets.
The MAX690 family was designed specifically for 3.0V/3.3V microprocessor systems needing integrated reset supervision, battery backup switchover, and watchdog protection - targeting reliability-critical embedded applications where discrete solutions increase board area and failure risk.
FAQ
What is the exact reset threshold voltage for MAX690RCPA?
The MAX690RCPA has a nominal reset threshold voltage of 2.625V for VCC falling, with a guaranteed range of 2.55V to 2.70V (±4% tolerance). This value is specified at temperature extremes and ensures reset assertion before VCC drops below 2.55V in 3.0V systems with ±10% supply tolerance. The rising threshold is 2.55V to 2.72V to accommodate 10mV hysteresis.
Does MAX690RCPA support lithium battery backup where VBATT exceeds VCC?
Yes, MAX690RCPA explicitly supports VBATT voltages exceeding VCC - such as a 3.6V lithium coin cell - during normal operation. Its internal battery switchover circuit activates when VCC falls below 2.40V (VSW), connecting VBATT to VOUT through a 140Ω switch. This design eliminates the need for external diodes or level shifters in battery-backed RAM applications.
Can the watchdog timer in MAX690RCPA be disabled?
No, the watchdog timer in MAX690RCPA cannot be disabled. It is a fixed-function block with a 1.6s timeout period (1.12s to 2.24s over temperature) that clears only on rising or falling edges at the WDI pin. If WDI is held static (high or low), the timer expires and triggers a reset pulse - a deliberate safety feature to prevent firmware lockup from going undetected.
What is the maximum allowable VCC transient duration that will not trigger a reset on MAX690RCPA?
For a VCC transient going 100mV below the reset threshold (i.e., 2.525V for MAX690RCPA), the maximum allowable duration without causing a reset is 40µs (typical at +25°C). This immunity is achieved via internal filtering and is graphically specified in Figure 7 of the datasheet. A 100nF bypass capacitor near the VCC pin further enhances glitch rejection.
How does MAX690RCPA handle manual reset (MR) input deassertion?
When the MR input transitions from low to high, MAX690RCPA holds RESET low for a full 200ms reset timeout period (tWP) regardless of VCC level - matching its power-on reset timing. This ensures consistent µP initialization whether triggered by power events or user action. MR has an internal 70µA pull-up, so it may be left floating if unused.
MAX690RCPA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX690RCPA FAQ
1.How can I place an order for MAX690RCPA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690RCPA 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 MAX690RCPA reliable?
The price and inventory of MAX690RCPA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690RCPA is usually 5 days.
3.What payment methods are accepted for MAX690RCPA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690RCPA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690RCPA?
MAX690RCPA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690RCPA 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 MAX690RCPA?
For technical support, including MAX690RCPA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690RCPA requirements.
6.How does Aetrix verify that MAX690RCPA is sourced from the original manufacturer or authorized distributors?
All MAX690RCPA 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 MAX690RCPA meets industry standards.
7.What is the process for return or replacement of MAX690RCPA?
All MAX690RCPA units undergo pre-shipment inspection (PSI). If there is an issue with MAX690RCPA, 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 MAX690RCPA part is unused and in its original packaging.
Return procedure for MAX690RCPA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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