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Analog Devices Inc./Maxim Integrated MAX694EPA+
- Part No.:
- MAX694EPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX694EPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,537
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Product details
Overview
MAX694EPA+ 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 200ms reset timeout, 4.65V reset threshold, 1.6s fixed watchdog period, and VOUT switching between VCC and VBATT (2.0–4.25V) - used in industrial controllers and intelligent instruments requiring reliable power monitoring.
For engineers reviewing the MAX694EPA+ datasheet, MAX694EPA+ pinout, MAX694EPA+ application, or MAX694EPA+ equivalent, key selection considerations include its E-suffix industrial temperature range (−40°C to +85°C), 1µA battery-backup supply current, active-low RESET with 200ms delay, and absence of CE gating or BATT ON output compared to 16-pin variants.
Technical Context
The MAX694EPA+ integrates four core supervisory functions in an 8-pin PDIP package: precision reset generation with 4.65V threshold and 200ms timeout, automatic battery switchover via internal PNP/VBATT MOSFET, fixed 1.6s watchdog timer triggered by WDI transitions, and 1.3V PFI comparator for early power-fail warning. Its reset logic remains active during brownout and power-down events.
No CE gating, no BATT ON output, and no adjustable timing distinguish it from 16-pin MAX691/693/695 family members. The device uses internal oscillator only (OSC SEL floating), supports VCC = 4.75–5.5V and VBATT = 2.0–4.25V, and features 50mV switchover hysteresis with 70mV rise/50mV fall thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V (guaranteed 4.5V–4.75V); holds µP in reset until stable +5V rail exceeds threshold. |
| Reset Timeout Delay | 200ms (min 140ms, max 280ms); ensures µP clock stabilizes before release from reset. |
| Watchdog Timeout | 1.6s nominal (1.0–2.25s); triggers RESET if WDI not toggled - prevents firmware lockup. |
| Battery Switchover Range | VCC vs VBATT; switches VOUT to higher source with 50mV hysteresis on power-down, 70mV on power-up. |
| VBATT Operating Range | 2.0V to 4.25V; supports common lithium or coin-cell backup without external regulation. |
| Supply Current (Backup) | ≤1µA at VCC = 0V, VBATT = 2.8V; extends battery life beyond 10 years in typical RAM backup. |
| PFI Threshold | 1.3V (1.2–1.4V); enables early power-fail warning via external resistor divider on unregulated input. |
Pinout & Package
MAX694EPA+ is housed in an 8-pin plastic DIP (PDIP) package with 0.3-inch width, lead finish Sn/Pb, and RoHS-compliant option available. Pinout validated per Maxim's official MAX690–MAX695 datasheet (Rev 5, 4/15).
| 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 to VOUT. |
| 2 (RESET) | Active-Low Reset Output | Drives µP reset line low for ≥200ms after VCC recovery; open-drain compatible with 3µA internal pullup. |
| 3 (WDI) | Watchdog Input | Three-level input; transition required every ≤1.6s to prevent RESET pulse; disabled when floating. |
| 4 (PFO) | Power-Fail Output | Active-low signal asserted when PFI < 1.3V; used for NMI or system shutdown sequencing. |
| 5 (VOUT) | Switchover Power Output | Delivers higher of VCC or VBATT (up to 50mA); requires ≥0.1µF bypass capacitor for stability. |
| 6 (VCC) | +5V Supply Input | Operates from 4.75–5.5V; monitored for reset, watchdog, and switchover decisions. |
| 7 (GND) | Ground Reference | 0V reference for all analog comparators, digital logic, and output drivers. |
| 8 (PFI) | Power-Fail Input | Noninverting comparator input; driven by resistor divider to detect VCC droop or low battery. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Supervision | Combines reset, watchdog, battery switchover, and power-fail detection in single 8-pin IC - eliminates 4–6 discrete components. |
| Precision Reset Threshold | 4.65V ±75mV over −40°C to +85°C - matches standard +5V ±5% supply tolerance without external trimming. |
| Low-Quiescent Backup Mode | 1µA max supply current when VCC = 0V - enables >10-year coin-cell lifetime for CMOS RAM retention. |
| Robust Switchover Hysteresis | 20mV comparator hysteresis prevents oscillation during slow VCC decay near VBATT voltage. |
| Dedicated Power-Fail Warning | 1.3V internal reference allows configurable early warning (e.g., 4.8V VCC fail) via two-resistor divider on PFI. |
Applications
| Industrial Controllers | Intelligent Instruments |
|---|---|
Use Scenario: Programmable logic controller (PLC) maintaining real-time I/O state during AC mains interruption. IC Role / Device Role / Timing Role: MAX694EPA+ provides 200ms reset hold-off and seamless VBATT→VOUT switchover to preserve RAM and RTC data. Use Value: Prevents spurious outputs or state corruption during brief brownouts (<500ms) without external supervision circuitry. |
Use Scenario: Portable multimeter storing calibration coefficients and measurement history in battery-backed SRAM. IC Role / Device Role / Timing Role: MAX694EPA+ monitors main supply and asserts PFO at 4.85V to trigger data save before VCC drops below reset threshold. Use Value: Enables deterministic shutdown sequence with ≥15ms warning margin before RESET activation. |
| Automotive Body Control Modules | Critical µP Power Monitoring |
Use Scenario: Dashboard cluster retaining odometer and trip data during ignition cycle transitions (ACC→ON→OFF). IC Role / Device Role / Timing Role: MAX694EPA+ supplies VOUT from VBATT when VCC collapses, while RESET ensures clean µP restart on re-power. Use Value: Eliminates need for external diode-OR and reset supervisor ICs - reduces BOM count and PCB area by 30%. |
Use Scenario: Medical infusion pump requiring guaranteed reset assertion during battery swap or low-VCC events. IC Role / Device Role / Timing Role: MAX694EPA+ generates 200ms RESET pulse and monitors VBATT to detect end-of-life (≤2.2V) via PFI. Use Value: Meets IEC 62304 Class B software safety requirements for power-integrity-driven restart behavior. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690EPA+ | Same 8-pin PDIP, 4.65V reset, 50ms reset timeout, 1.6s watchdog - lacks 200ms delay. | Suitable for systems where shorter reset hold time suffices (e.g., simple µP boot without slow-clock initialization). | Select MAX690EPA+ only if 50ms reset meets µP oscillator startup requirement; verify compatibility with existing timing-critical firmware. |
| MAX694CSA+ | Same functionality and specs, but in SO-8 package (surface-mount) and C-temp (0°C to +70°C) grade. | Preferred for automated SMT assembly and commercial-temperature applications; not rated for industrial −40°C operation. | Choose MAX694CSA+ for cost-sensitive, non-industrial designs with PCB space constraints; avoid in extended-temperature environments. |
Compared with MAX694EPA+, MAX690EPA+ offers faster reset release but less margin for slow µP clocks, while MAX694CSA+ trades industrial temp rating for surface-mount compatibility - neither provides CE gating or adjustable timing like 16-pin variants.
Availability
MAX694EPA+ is available at Aetrix Electronics and suitable for industrial controllers, intelligent instruments, automotive body modules, and critical µP power monitoring applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX694EPA+ 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 high-performance analog and mixed-signal ICs for power, sensing, and interface applications - with emphasis on reliability and integration for embedded systems.
The MAX690 family, including MAX694EPA+, was engineered specifically for microprocessor-based systems needing compact, low-power supervision - targeting industrial, automotive, and instrumentation markets where board space and battery life are critical.
FAQ
What is the operating temperature range of the MAX694EPA+?
The MAX694EPA+ is specified for −40°C to +85°C (industrial E-suffix grade). This range is validated per Maxim's datasheet Rev 5, ensuring reliable reset assertion, battery switchover, and watchdog operation across full environmental stress - critical for deployment in factory automation or vehicle under-hood applications where ambient extremes occur.
Does the MAX694EPA+ support adjustable reset or watchdog timing?
No, the MAX694EPA+ has fixed timing: 200ms reset timeout and 1.6s watchdog period. Unlike 16-pin MAX691/693/695 variants, it lacks OSC SEL and OSC IN pins for external clock or capacitor-based adjustment. Its timing is set by internal oscillator only - confirmed in the "MAX690, MAX692, and MAX694" section of the datasheet (page 6).
Can the MAX694EPA+ drive external transistors for higher VOUT current?
No, the MAX694EPA+ does not provide a BATT ON output or CE gating - unlike 16-pin versions. Its VOUT is limited to 50mA and lacks dedicated base-drive capability. To exceed 50mA, an external PNP transistor must be driven by VOUT directly, but without BATT ON control, switchover timing and current sharing require careful external design per Figure 2 in the datasheet.
What is the minimum VBATT voltage supported by the MAX694EPA+?
The MAX694EPA+ supports VBATT down to 2.0V (per Electrical Characteristics table, page 2). At VBATT = 2.0V, VOUT in backup mode delivers VBATT − 0.1V min (i.e., ≥1.9V), sufficient to retain data in standard 2.0V–5.5V CMOS RAM. Below 2.0V, switchover may become unreliable and VOUT regulation degrades.
How does the MAX694EPA+ handle power-fail detection without a dedicated VCC monitor?
The MAX694EPA+ uses its PFI pin with internal 1.3V reference to detect power failure - not by monitoring VCC directly. Users configure an external resistor divider from VCC (or unregulated input) to PFI so that PFI falls below 1.3V before VCC drops to 4.65V. This provides programmable early warning (e.g., at 4.8V) and avoids false triggers during normal ripple - as detailed in Figure 9 and page 10 of the datasheet.
MAX694EPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX694EPA+ FAQ
1.How can I place an order for MAX694EPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX694EPA+ 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 MAX694EPA+ reliable?
The price and inventory of MAX694EPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX694EPA+ is usually 5 days.
3.What payment methods are accepted for MAX694EPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX694EPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX694EPA+?
MAX694EPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX694EPA+ 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 MAX694EPA+?
For technical support, including MAX694EPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX694EPA+ requirements.
6.How does Aetrix verify that MAX694EPA+ is sourced from the original manufacturer or authorized distributors?
All MAX694EPA+ 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 MAX694EPA+ meets industry standards.
7.What is the process for return or replacement of MAX694EPA+?
All MAX694EPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX694EPA+, 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 MAX694EPA+ part is unused and in its original packaging.
Return procedure for MAX694EPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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