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Analog Devices Inc./Maxim Integrated MAX690CPA
- Part No.:
- MAX690CPA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX690CPA.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,534
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Product details
Overview
The MAX690CPA from Maxim Integrated is an 8-pin microprocessor supervisory circuit providing reset generation, battery backup switchover, watchdog timer, and 1.3V power-fail detection for +5V systems. It delivers a precise 4.65V reset threshold, 50ms reset timeout, fixed 1.6s watchdog timeout, and VOUT switching between VCC and VBATT - all in a PDIP-8 package. It is used in embedded controllers and industrial instrumentation to ensure reliable µP startup, brownout recovery, and RAM data retention during power loss.
For engineers reviewing the MAX690CPA datasheet, MAX690CPA pinout, MAX690CPA application, or MAX690CPA equivalent, key selection considerations include its fixed-reset timing, absence of CE gating or adjustable timeouts (unlike MAX691/MAX695), compatibility with 2.0–4.25V backup batteries, and suitability for cost-sensitive, space-constrained µP systems requiring basic supervision without programmability.
Technical Context
The MAX690CPA integrates four core supervision functions in a single monolithic IC: a precision voltage monitor with 4.65V ±150mV reset threshold and 40mV hysteresis; a battery switchover circuit that connects VOUT to the higher of VCC or VBATT with 50–70mV switchover window and 20mV hysteresis; a fixed 1.6s watchdog timer triggered by WDI transitions; and a 1.3V comparator for PFI-based power-fail or low-battery warning. All logic operates from VCC or VBATT, with internal biasing ensuring stable operation across temperature.
No external timing components are required: reset delay is internally set to 50ms, watchdog timeout is fixed at 1.6s nominal, and PFO assertion occurs when PFI drops below 1.3V. The device lacks CE gating, OSC SEL/OSC IN pins, or BATT ON output - distinguishing it from 16-pin family members like MAX691 and confirming its role as a minimal-feature, pin-compatible entry-level supervisor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V (min 4.5V, max 4.75V) - ensures reliable reset assertion before µP fails under +5V ±5% supply tolerance |
| Reset Timeout Delay | 50ms - holds RESET low long enough for crystal oscillator startup and µP initialization |
| Watchdog Timeout | 1.6s (nominal) - detects software lockup without requiring external timing elements |
| Battery Switchover Range | VCC = 4.75–5.5V, VBATT = 2.0–4.25V - supports common lithium or coin-cell backup sources |
| VOUT Output Capability | 50mA from VCC, 250µA from VBATT - powers CMOS RAM directly without external pass transistor |
| Supply Current (Active) | 2–5mA - enables low-power monitoring without burdening main supply |
| Standby Current (VBATT only) | 0.6–1µA - extends battery life to years in memory-retention standby mode |
Pinout & Package
MAX690CPA is housed in an 8-pin plastic DIP (PDIP-8) package with 0.3-inch width, through-hole mounting, and industry-standard pin spacing. Pin 1 is marked with a notch or dot; pin numbering proceeds counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VBATT) | Backup Battery Input | Connects to 2.0–4.25V battery; internally compared to VCC to enable switchover; tie to GND if unused |
| 2 (RESET) | Active-Low Reset Output | Drives µP reset line low during power-up, brownout, or watchdog timeout; includes 3µA internal pullup |
| 3 (WDI) | Watchdog Input | Three-level input (low/mid/high); toggling within 1.6s prevents reset; floating disables watchdog |
| 4 (PFO) | Power-Fail Output | Open-drain output goes low when PFI < 1.3V; used for NMI or alarm signaling on impending power loss |
| 5 (VOUT) | Switched Power Output | Delivers higher of VCC or VBATT to RAM; 50mA capable from VCC, 250µA from VBATT |
| 6 (VCC) | +5V Supply Input | Main system supply input; monitored for reset and switchover; absolute max 6.0V |
| 7 (PFI) | Power-Fail Input | Noninverting comparator input; connect via resistor divider to monitor regulated/unregulated rail for early warning |
| 8 (GND) | Ground Reference | 0V reference for all analog and digital functions; must be low-impedance connection |
Key Features
| Feature | Design Value |
|---|---|
| Precision 4.65V Reset Threshold | Guaranteed 4.5V–4.75V range with 40mV hysteresis ensures robust immunity to supply noise and avoids chatter during slow VCC ramps |
| Integrated Battery Switchover | Automatic VOUT sourcing from VBATT when VCC drops below VBATT −70mV, enabling seamless RAM backup without external MOSFET or control logic |
| Self-Contained Watchdog Timer | Fixed 1.6s timeout requires no external capacitor or clock - reduces BOM count and layout complexity in basic supervision applications |
| Low-Power Backup Mode | 1µA max quiescent current when VCC = 0V and VBATT = 2.8V extends typical CR2032 battery life beyond 10 years in memory-retention use |
| Dedicated Power-Fail Detection | 1.3V comparator with ±25nA input bias allows high-impedance resistor-divider monitoring of any rail - unregulated input, +5V, or battery voltage |
Applications
| Industrial Controller Supervision | Embedded Data Logger Power Management |
|---|---|
|
Use Scenario: PLC or RTU maintaining real-time clock and configuration EEPROM during AC mains interruption. IC Role / Device Role / Timing Role: MAX690CPA provides brownout reset, switches VOUT to backup battery, and asserts PFO to trigger immediate data save before VCC falls below 4.65V. Use Value: Prevents corruption of nonvolatile memory during grid instability using only one IC and no external timing components. |
Use Scenario: Remote environmental sensor node powered by 5V adapter, backed by coin cell, logging data hourly. IC Role / Device Role / Timing Role: MAX690CPA monitors VCC for adapter failure, activates battery switchover, and uses PFI to detect battery depletion below 2.2V. Use Value: Enables >5-year maintenance-free operation with guaranteed RAM retention and low-battery warning via PFO. |
| Medical Instrument Boot Integrity | Automotive Body Control Module (BCM) Reset Coordination |
|
Use Scenario: Portable diagnostic device requiring deterministic boot sequence and fail-safe RAM initialization after power cycling. IC Role / Device Role / Timing Role: MAX690CPA generates 50ms active-low RESET pulse synchronized to VCC rise, ensuring µP completes oscillator startup before executing code. Use Value: Eliminates need for RC reset circuit and associated calibration drift, meeting IEC 60601-1 reliability requirements. |
Use Scenario: BCM managing door locks, lighting, and CAN transceivers where supply voltage dips during load dump or cranking. IC Role / Device Role / Timing Role: MAX690CPA asserts RESET during cranking-induced brownouts (<4.65V) and uses WDI to detect firmware hangs caused by EMI-induced crashes. Use Value: Provides dual-layer protection (supply monitoring + software watchdog) without increasing PCB area or thermal load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX692CPA | 4.4V reset threshold (vs. 4.65V); same 8-pin PDIP, 50ms reset, 1.6s watchdog, no CE gating | Designed for +5V ±10% supplies; suitable where tighter VCC tolerance or lower reset threshold is required | Select MAX692CPA when system VCC may dip to 4.5V regularly and 4.65V reset would cause nuisance resets |
| TPS3808G18DBVR | Adjustable reset threshold (via external resistor), 200ms min delay, 1.8V–6.0V supply, SOT-23-6 package | Lacks battery switchover and PFI comparator; adds manual reset input and watchdog disable pin | Choose TPS3808G18DBVR when board space is critical and battery backup is handled separately, but adjustable reset voltage is needed |
Compared with MAX690CPA, MAX692CPA offers lower reset voltage for wider supply tolerance but identical supervision architecture, while TPS3808G18DBVR trades integrated battery management for compact size and voltage flexibility - making MAX690CPA optimal where unified power monitoring, backup, and watchdog are required in legacy through-hole designs.
Availability
MAX690CPA is available at Aetrix Electronics and suitable for industrial controllers, medical instrumentation, automotive body electronics, and embedded data loggers requiring stable component supply with long-term manufacturability and consistent parametric performance.
Supply support for MAX690CPA 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 applications.
The MAX690CPA belongs to the MAX690–MAX695 supervisory circuit family, designed specifically to replace discrete reset generators, battery switches, and watchdog timers in microprocessor-based systems - reducing component count and improving system-level reliability.
FAQ
What is the reset threshold voltage of the MAX690CPA, and how does it behave during power-up?
The MAX690CPA has a guaranteed reset threshold of 4.65V (minimum 4.5V, maximum 4.75V) with 40mV hysteresis. During power-up, RESET remains low until VCC rises above 4.75V, then stays asserted for a fixed 50ms timeout - ensuring the microprocessor's oscillator stabilizes before release. This behavior is fully internal; no external capacitor or resistor is needed to set the delay. The MAX690CPA implements this using a monostable circuit synchronized to the internal timebase, and the same 50ms delay applies after watchdog-triggered resets.
Can the MAX690CPA be used with a 3.3V microprocessor system?
No, the MAX690CPA is not suitable for direct use with 3.3V µP systems. Its reset threshold is fixed at 4.65V, and it requires VCC = 4.75–5.5V to operate correctly. Applying 3.3V to VCC will prevent proper reset generation and may violate the device's minimum operating voltage specification. For 3.3V systems, consider alternatives such as the MAX6326 (3.08V threshold) or TPS3808G33 - both of which are pin-compatible replacements designed for lower-voltage rails. The MAX690CPA must be used only in +5V environments.
How does the MAX690CPA handle battery backup switchover, and what are the voltage limits?
The MAX690CPA automatically switches VOUT between VCC and VBATT based on relative voltage levels: VOUT connects to VBATT when VCC falls below VBATT −70mV (power-down), and reconnects to VCC when VCC rises above VBATT +50mV (power-up), with 20mV hysteresis preventing oscillation. VBATT must be 2.0–4.25V; VCC must be 4.75–5.5V. In backup mode, VOUT delivers VBATT −0.1V at 250µA, with only 1µA typical supply current - enabling multi-year operation from a CR2032. No external transistor or control logic is required.
Does the MAX690CPA support adjustable watchdog timeout or reset delay?
No, the MAX690CPA does not support adjustable watchdog timeout or reset delay. Its watchdog timeout is fixed at 1.6s (nominal), and its reset timeout is fixed at 50ms - both implemented entirely within the die using internal oscillators and counters. Unlike the 16-pin MAX691/MAX695, the MAX690CPA omits OSC SEL and OSC IN pins, eliminating external timing configuration. This makes the MAX690CPA ideal for cost-sensitive, fixed-timing applications where simplicity and predictability outweigh programmability - confirmed by its pinout and functional description in the official datasheet.
What is the function of the PFI and PFO pins on the MAX690CPA, and how are they typically connected?
PFI (Pin 7) is the noninverting input of a 1.3V comparator; PFO (Pin 4) is its open-drain output. When PFI voltage drops below 1.3V, PFO pulls low - signaling imminent power failure or low battery. Typically, PFI connects to a resistor divider from the monitored rail (e.g., unregulated 8V input or regulated 5V output), sized so PFI = 1.3V when the rail reaches the desired warning threshold (e.g., 4.8V). PFO can drive a µP NMI line directly or interface with external logic. The MAX690CPA's PFI accepts ±25nA input current, enabling high-impedance, low-power monitoring without loading the source rail.
MAX690CPA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- 35ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX690CPA FAQ
1.How can I place an order for MAX690CPA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX690CPA 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 MAX690CPA reliable?
The price and inventory of MAX690CPA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX690CPA is usually 5 days.
3.What payment methods are accepted for MAX690CPA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX690CPA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX690CPA?
MAX690CPA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX690CPA 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 MAX690CPA?
For technical support, including MAX690CPA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX690CPA requirements.
6.How does Aetrix verify that MAX690CPA is sourced from the original manufacturer or authorized distributors?
All MAX690CPA 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 MAX690CPA meets industry standards.
7.What is the process for return or replacement of MAX690CPA?
All MAX690CPA units undergo pre-shipment inspection (PSI). If there is an issue with MAX690CPA, 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 MAX690CPA part is unused and in its original packaging.
Return procedure for MAX690CPA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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