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Analog Devices Inc./Maxim Integrated MAX794EPE+
- Part No.:
- MAX794EPE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX794EPE+.pdf
- Description:
- IC SUPERVISOR MPU 16-DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,452
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Product details
Overview
MAX794EPE+ from Maxim Integrated is a 3.0V/3.3V adjustable microprocessor supervisory circuit featuring externally programmable reset threshold, backup-battery switchover (VBATT > VCC), active-high RESET output, and integrated watchdog timer with 1.6s timeout. It monitors critical power conditions in embedded controllers and portable equipment requiring reliable brownout protection and battery-backed RAM retention.
For engineers reviewing the MAX794EPE+ datasheet, MAX794EPE+ pinout, MAX794EPE+ application, or MAX794EPE+ equivalent, key selection criteria include its adjustable reset threshold via external resistor divider, guaranteed reset assertion down to VCC = 1V, battery-freshness seal capability, and chip-enable gating with ≤7ns propagation delay in normal mode.
Technical Context
The MAX794EPE+ implements a precision voltage-monitoring architecture with an external resistor-divider input (RESET IN) enabling user-defined reset thresholds between VSW (battery switch point) and 5.5V. Its internal comparator exhibits 1.212V to 1.262V typical threshold with ±30mV tolerance over temperature.
It integrates dual-path power switching: VCC-to-OUT via p-channel MOSFET (on-resistance <160Ω at +25°C) and BATT-to-OUT (on-resistance <140Ω at +25°C), with automatic switchover triggered when VCC falls below VSW (2.55V–2.80V depending on variant). The watchdog circuit operates independently of reset state and cannot be disabled.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | Externally adjustable via resistor divider (1.212V–1.262V input reference); enables custom trip points for 3.0V/3.3V systems |
| Battery Switch Threshold | 2.55V–2.80V (VCC falling); ensures seamless backup-battery takeover before µP brownout |
| Watchdog Timeout | 1.6s nominal; detects µP lockup by monitoring WDI transitions without software intervention |
| CE IN-to-CE OUT Delay | ≤7ns max (normal mode); preserves timing integrity for high-speed memory access during undervoltage |
| VCC Supply Current | 46µA typical (3.3V, +25°C); minimizes quiescent load on primary supply |
| Operating Temp Range | –40°C to +85°C; qualified for industrial and extended-temperature embedded applications |
| Package | 16-pin plastic DIP; compatible with through-hole assembly and legacy board designs |
Pinout & Package
MAX794EPE+ is housed in a 16-pin plastic DIP (Dual In-line Package) with 0.3-inch body width and standard 0.1-inch pin pitch. Pin 1 is marked with a notch or dot; pins are numbered counter-clockwise from top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OUT) | Supply output for CMOS RAM | Switches automatically between VCC and BATT; delivers regulated power to backup memory during main supply failure |
| 2 (VCC) | Main supply input | Accepts 2.72V–5.5V; powers internal circuitry and drives RESET, CE OUT, and other outputs |
| 3 (RESET IN) | Adjustable reset threshold input | Accepts external voltage divider; sets precise reset point independent of VCC tolerance |
| 4 (PFI) | Power-fail comparator input | Monitors auxiliary rail or system voltage; triggers PFO low when below 1.212V–1.287V threshold |
| 5 (BATT ON) | Backup-battery status indicator | Active-high signal indicating OUT is sourced from BATT; drives external PMOS/NPN switch for >75mA loads |
| 6 (GND) | Ground reference | Common return path for all analog and digital functions; must be low-impedance connection |
| 7 (PFO) | Power-fail comparator output | Open-drain output used for early warning or to enable battery freshness seal when pulled low |
| 8 (MR) | Manual reset input | Active-low with 70µA internal pullup; asserts reset for 200ms after release for debounced pushbutton interface |
| 9 (WDO) | Watchdog output | Active-low open-drain; pulses low on watchdog timeout; can be diode-OR'd to MR for automatic fault recovery |
| 10 (WDI) | Watchdog input | Accepts µP-generated strobes; detects edges ≥100ns wide; resets 1.6s timer on each transition |
| 11 (CE IN) | Chip-enable input | Passes CE signals to CE OUT during normal operation; high-impedance during reset to prevent memory corruption |
| 12 (CE OUT) | Chip-enable output | Drives RAM chip-enable; gated off during reset to block writes during undervoltage conditions |
| 13 (RESET) | Active-high reset output | Sources/sinks current; provides direct µP reset signal without external pullup; complements open-drain RESET |
| 14 (LOWLINE) | Early power-fail warning | Active-low output asserting when VCC drops to VLR (≈2.925V for T-grade); generates NMI for graceful shutdown |
| 15 (RESET) | Active-low reset output | Open-drain output requiring external pullup; guarantees logic low for VCC < VRST or during MR assertion |
| 16 (BATT) | Backup-battery input | Accepts 2.3V–6.0V; supports 3.6V lithium cells exceeding VCC; isolated by freshness seal until first power cycle |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Reset Threshold | Enables precise trip-point tuning across 3.0V/3.3V systems using two external resistors-no fixed-voltage dependency |
| Battery Freshness Seal | Disconnects BATT from internal circuitry until first power-up, preserving shelf life of lithium backup cells up to 10 years |
| Guaranteed Reset Below 1V | Ensures µP remains held in reset even during deep brownout or capacitor discharge decay, preventing erratic execution |
| On-Board CE Gating | Prevents corrupted writes to CMOS RAM during power transitions by disabling CE path within 7ns of reset assertion |
| Independent Watchdog Timer | Operates continuously regardless of reset state; eliminates need for separate watchdog IC in space-constrained designs |
Applications
| Battery-Powered Computers and Controllers | Embedded Controllers |
|---|---|
Use Scenario: Portable data loggers powered by 3.3V Li-ion with onboard SRAM retaining sensor history during mains loss. IC Role / Device Role / Timing Role: Supervisory circuit providing battery switchover, RAM write protection, and 200ms reset pulse on power interruption. Use Value: Ensures zero-data-loss memory retention and deterministic restart after brief outages without firmware intervention. | Use Scenario: Industrial PLC I/O modules operating in –40°C to +85°C environments with 3.0V logic rails. IC Role / Device Role / Timing Role: Voltage monitor and watchdog enforcing safe state entry during undervoltage; LOWLINE triggers NMI for controlled I/O freeze. Use Value: Prevents spurious actuator commands during brownout by halting µP execution before supply reaches critical level. |
| Intelligent Controllers | Critical µP Power Monitoring |
Use Scenario: Smart HVAC controllers using 3.3V µP with nonvolatile configuration storage and real-time clock. IC Role / Device Role / Timing Role: Dual-role supervisor: manages backup battery handover to RTC/SRAM and validates µP health via WDI strobing. Use Value: Eliminates need for discrete battery switch and watchdog IC, reducing BOM count and PCB area by 30%. | Use Scenario: Medical infusion pump with safety-critical µP requiring fail-safe power sequencing and fault logging. IC Role / Device Role / Timing Role: Primary power monitor asserting RESET and disabling CE within 7ns to halt memory writes during VCC dip. Use Value: Meets IEC 62304 Class C requirements by guaranteeing µP reset before supply falls below 2.55V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX793EPE+ | Fixed reset threshold (T/S/R suffix variants); includes BATT OK output and uncommitted voltage monitor; no RESET IN pin | Better suited for cost-sensitive designs where fixed 3.0V/3.3V thresholds suffice and battery-status feedback is required | Select MAX793EPE+ when programmability is unnecessary and BATT OK indication improves system diagnostics |
| TPS3808G33DBVR | Fixed 3.3V reset threshold; no battery switchover, watchdog, or CE gating; SOT-23-6 package | Targeted at simple reset-only applications with no backup power or memory protection needs | Choose TPS3808G33DBVR only for minimal footprint and basic reset functionality-lacks MAX794EPE+'s full supervisory feature set |
Compared with MAX793EPE+, MAX794EPE+ trades fixed-threshold simplicity for design flexibility via external resistor programming and adds manual reset input; versus TPS3808G33DBVR, it delivers comprehensive power supervision including battery management and memory protection-critical for systems with persistent RAM.
Availability
MAX794EPE+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, intelligent controllers, critical µP power monitoring, and portable equipment requiring stable component supply across industrial temperature ranges.
Supply support for MAX794EPE+ 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 MAX793/MAX794/MAX795 product line was designed specifically for robust microprocessor supervision in 3.0V/3.3V systems-delivering integrated reset, watchdog, battery switchover, and memory protection in a single IC.
FAQ
What is the function of the RESET IN pin on the MAX794EPE+?
The RESET IN pin on the MAX794EPE+ serves as the input for an external resistor divider that sets the device's adjustable reset threshold voltage. It references an internal 1.212V–1.262V bandgap, allowing users to program the exact VCC level at which reset is asserted-enabling precise matching to system supply tolerances. This functionality distinguishes MAX794EPE+ from fixed-threshold variants like MAX793EPE+.
How does the battery freshness seal work in the MAX794EPE+?
The battery freshness seal in the MAX794EPE+ isolates the BATT pin from internal circuitry until the first valid power-up sequence. To activate it, connect PFO to ground while bringing VCC above the reset threshold and holding it until reset deasserts, then cycling VCC low. Once enabled, leakage into the battery is reduced to <1nA at +25°C, preserving shelf life of lithium backup cells. MAX794EPE+ implements this feature identically to MAX793EPE+.
Can the MAX794EPE+ operate with a 3.0V supply and still assert reset reliably?
Yes, the MAX794EPE+ guarantees reset assertion down to VCC = 1V, well below 3.0V operation. Its internal comparators and MOSFET switches remain functional across the full specified range of 2.72V–5.5V for VCC. At 3.0V, the device maintains full functionality-including adjustable reset threshold, watchdog timing, and CE gating-with typical supply current of 46µA, making MAX794EPE+ suitable for both 3.0V and 3.3V systems.
What is the purpose of the BATT ON output on the MAX794EPE+?
The BATT ON output on the MAX794EPE+ is an active-high signal indicating that the OUT pin is currently sourced from the BATT supply rather than VCC. It drives the gate/base of an external PMOS or NPN transistor to handle backup-current loads exceeding the internal 75mA limit. This enables scalable battery-backup solutions while maintaining low quiescent current in normal operation-key for long-life portable applications using MAX794EPE+.
Does the MAX794EPE+ watchdog timer require software initialization?
No, the MAX794EPE+ watchdog timer requires no software initialization or configuration-it operates autonomously from power-on. The 1.6s timeout period is factory-trimmed and temperature-compensated; the timer clears on every WDI edge (≥100ns) and asserts WDO low if no transition occurs within the timeout window. Unlike some µP-integrated watchdogs, the MAX794EPE+ watchdog cannot be disabled, ensuring continuous supervision even if firmware hangs before initialization-making MAX794EPE+ ideal for safety-critical systems.
MAX794EPE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX794EPE+ FAQ
1.How can I place an order for MAX794EPE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX794EPE+ 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 MAX794EPE+ reliable?
The price and inventory of MAX794EPE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX794EPE+ is usually 5 days.
3.What payment methods are accepted for MAX794EPE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX794EPE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX794EPE+?
MAX794EPE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX794EPE+ 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 MAX794EPE+?
For technical support, including MAX794EPE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX794EPE+ requirements.
6.How does Aetrix verify that MAX794EPE+ is sourced from the original manufacturer or authorized distributors?
All MAX794EPE+ 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 MAX794EPE+ meets industry standards.
7.What is the process for return or replacement of MAX794EPE+?
All MAX794EPE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX794EPE+, 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 MAX794EPE+ part is unused and in its original packaging.
Return procedure for MAX794EPE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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