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Analog Devices Inc./Maxim Integrated MAX794ESE+
- Part No.:
- MAX794ESE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX794ESE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:105
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Product details
Overview
MAX794ESE+ from Maxim Integrated is a 3.0V/3.3V adjustable microprocessor supervisory circuit featuring externally programmable reset threshold, backup-battery switchover (VBATT > VCC), independent watchdog timer (1.6s timeout), and chip-enable signal gating with ≤7ns propagation delay. It operates across –40°C to +85°C and supports battery-freshness sealing for long-term storage in portable controllers.
For engineers reviewing the MAX794ESE+ datasheet, MAX794ESE+ pinout, MAX794ESE+ application, or MAX794ESE+ equivalent, key selection criteria include adjustable reset threshold via resistor divider, guaranteed reset assertion down to VCC = 1V, battery-switching hysteresis (15mV typical), and CE IN-to-CE OUT timing compatibility with high-speed µPs.
Technical Context
The MAX794ESE+ implements an external resistor-divider–controlled reset comparator with VRST IN threshold of 1.212V to 1.287V (typical), enabling precise reset point selection between VSW (2.55V–2.95V) and 5.5V. Its battery switchover logic uses dual comparators with 15mV hysteresis to prevent oscillation during VCC transitions near VSW.
It integrates a non-disableable 1.6s watchdog timer monitored via WDI, with WDO output capable of driving MR directly for fault-triggered reset. The CE gating path includes a transmission gate with 46Ω on-resistance and <10µs disable holdover when reset asserts-ensuring RAM write completion during brownout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | Externally adjustable via resistor divider; range: VSW to 5.5V (VSW = 2.55V–2.95V depending on VCC) |
| Watchdog Timeout | 1.6s fixed; ensures µP activity monitoring without software intervention |
| Battery Switch Threshold | VSW = 2.55V–2.95V (VCC falling); enables seamless switchover to 3.6V Li battery even when VCC < VBATT |
| CE IN-to-CE OUT Delay | ≤7ns max; preserves timing integrity for fast µP address/data bus gating |
| Operating Temp Range | –40°C to +85°C; qualified for industrial embedded controller environments |
| VCC Supply Current | 46µA typ at +25°C (VCC = 3.3V); ultra-low quiescent power for battery-backed systems |
| Reset Assertion Guarantee | Valid down to VCC = 1V; ensures reliable reset under deep brownout conditions |
Pinout & Package
MAX794ESE+ is housed in a 16-pin narrow SO (SOIC-16) package with 1.27mm pitch, RoHS-compliant lead-free finish (+ suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT (Pin 1) | Supply output for CMOS RAM | Switches between VCC and BATT using internal p-MOSFET; low on-resistance (<160Ω at +25°C) minimizes voltage drop |
| RESET IN (Pin 3) | Adjustable reset threshold input | Accepts external resistor divider; sets VRST = VRST_IN × (R1/R2 + 1); VRST_IN = 1.212–1.287V |
| VCC (Pin 2) | Main supply input | Operates from 2.72V to 5.5V; powers all internal circuits except battery path |
| PFO (Pin 7) | Power-fail comparator output / freshness seal enable | Open-drain; pulled low when PFI < VPFT or VCC < VSW; used to latch battery freshness seal |
| RESET (Pin 15) | Active-low open-drain reset output | Asserts low for ≥200ms on power-up/brownout; requires external pullup (4.7kΩ–1MΩ) |
| CE IN (Pin 11) | Chip-enable input | High-impedance when reset active; enables gating of µP CE signals to protect RAM writes |
| CE OUT (Pin 12) | Chip-enable output | Passes CE IN only when reset inactive; 10µs holdover if CE IN low at reset assertion |
| MR (Pin 8) | Manual reset input | Active-low with 70µA internal pullup; asserts reset for 200ms after rising edge |
| WDI (Pin 10) | Watchdog input | Detects edges ≥100ns wide; resets 1.6s timer on each transition |
| WDO (Pin 9) | Watchdog output | Active-low; goes low on watchdog timeout; can drive MR directly for automatic fault recovery |
| LOWLINE (Pin 14) | Early power-fail warning | Active-low NMI trigger; asserts when VCC falls to VLR = VRST − (5–60mV) |
| BATT (Pin 16) | Backup battery input | Accepts up to 6V; enables switchover even when VBATT > VCC (e.g., 3.6V Li on 3.3V system) |
| BATT ON (Pin 5) | Battery status indicator | Active-high; signals BATT is active on OUT; drives external PMOS switch for >75mA loads |
| GND (Pin 6) | Ground reference | Common return for VCC, BATT, and all I/O; decoupling required at pin |
| PFI (Pin 4) | Power-fail comparator input | Monitors external rail; triggers PFO low when below VPFT = 1.212–1.287V |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Reset Threshold | Set precisely via external resistor divider-no factory binning required; supports custom supply tolerances |
| Battery-Freshness Seal | Disables battery leakage (<1nA at +25°C) until first power-up, preserving shelf life of sealed systems |
| Guaranteed Reset Below 1V | Ensures deterministic reset behavior even during severe brownout-critical for data integrity in industrial logging |
| Sub-10ns CE Gating Delay | Maintains µP bus timing margins without adding wait states or requiring layout rework |
| Non-Disableable Watchdog | Eliminates risk of accidental watchdog disable in firmware-mandatory for safety-critical embedded control |
Applications
| Portable Data Logger | Industrial PLC I/O Module |
|---|---|
Use Scenario: Battery-powered environmental sensor node recording temperature/humidity every 5 minutes, with RAM retention during mains loss. IC Role / Device Role / Timing Role: Supervisory IC providing backup power switchover, RAM write protection via CE gating, and brownout-triggered reset to preserve last valid reading. Use Value: Enables 10-year shelf life via battery freshness seal and guarantees RAM integrity during 200ms reset window-even when VCC drops to 1.0V. | Use Scenario: DIN-rail mounted I/O module with isolated analog inputs, powered by 24VDC converted to 3.3V, operating in factory environments with voltage transients. IC Role / Device Role / Timing Role: Power supervisor detecting early VCC sag (via LOWLINE), asserting reset before µP executes corrupted code, and gating CE to prevent spurious writes during undervoltage. Use Value: Prevents field failures caused by transient-induced memory corruption-verified by 1.6s watchdog catching stalled firmware loops. |
| Medical Infusion Pump Controller | Ruggedized Handheld Terminal |
Use Scenario: Safety-critical infusion pump with nonvolatile RAM storing dosage history and alarm logs, powered by rechargeable Li-ion. IC Role / Device Role / Timing Role: Dual-role supervisor: monitors main 3.3V rail for brownout (RESET), while using PFI to track battery health and trigger low-battery warnings (PFO). Use Value: Meets IEC 62304 Class C requirements via guaranteed reset assertion down to 1V and battery-switchover hysteresis eliminating chatter during battery discharge. | Use Scenario: Rugged Android-based terminal used in warehouses, subject to frequent battery swaps and ESD events. IC Role / Device Role / Timing Role: Supervisor managing 3.3V rail, enabling battery-freshness seal during shipping, and providing manual reset (MR) with noise immunity (0.1µF cap support). Use Value: Reduces field returns by 37% (per OEM data) through robust MR debounce and 15mV VSW hysteresis rejecting supply ripple false triggers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX793ESE+ | Fixed reset threshold (T/S/R variants); includes BATT OK output and uncommitted voltage monitor; no RESET IN pin | Better suited for cost-sensitive designs where reset point is known and battery status reporting is required | Select MAX793ESE+ when fixed 3.00V/2.85V/2.55V thresholds meet system specs and BATT OK indication adds value |
| TPS3808G33DBVR | Fixed 3.3V reset threshold; no battery switchover, no watchdog, no CE gating; lower IQ (1.5µA) | Targeted at simple power-monitoring-only applications without backup power or RAM protection needs | Choose TPS3808G33DBVR only for basic reset generation where battery backup and watchdog are unnecessary |
Compared with MAX793ESE+, the MAX794ESE+ trades BATT OK output for full reset threshold adjustability and retains watchdog/CE gating-making it optimal for flexible, battery-backed µP systems. Versus TPS3808G33DBVR, it delivers comprehensive supervision (switchover, watchdog, CE control) at higher IQ but essential for mission-critical reliability.
Availability
MAX794ESE+ is available at Aetrix Electronics and suitable for industrial PLC modules, portable medical devices, ruggedized handheld terminals, and battery-backed data loggers requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX794ESE+ 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 precision analog and mixed-signal ICs for industrial, automotive, and computing applications-with emphasis on power management, sensing, and interface solutions.
The MAX793/MAX794/MAX795 family was engineered specifically for 3.0V/3.3V microprocessor systems needing integrated battery backup, early power-fail warning, and hardware-enforced RAM write protection-addressing reliability gaps in portable and industrial controllers.
FAQ
What is the exact reset threshold range supported by the MAX794ESE+?
The MAX794ESE+ does not have a fixed reset threshold. Its reset point is set externally via a resistor divider on the RESET IN pin, with VRST_IN = 1.212V to 1.287V (typ). Using the formula VRST = VRST_IN × (R1/R2 + 1), the achievable reset threshold spans from the battery switch threshold VSW (2.55V–2.95V) up to 5.5V-enabling precise matching to custom supply tolerances. This flexibility is unique to the MAX794ESE+ within the MAX793/4/5 family.
How does the battery freshness seal work on the MAX794ESE+ and how is it enabled?
The MAX794ESE+ battery freshness seal disconnects the backup battery from internal circuitry until first use, reducing leakage to <1nA at +25°C and preserving shelf life. To enable it: connect battery to BATT, ground PFO, bring VCC above VRST, hold until reset deasserts (≥200ms), then cycle VCC low and high again. Once enabled, the seal remains active until VCC exceeds VRST. Note that MAX794ESE+ supports this feature identically to MAX793, despite lacking BATT OK output.
Can the MAX794ESE+ watchdog timer be disabled, and what happens if WDI is held static?
No-the MAX794ESE+ watchdog timer cannot be disabled. If WDI is held continuously high or low beyond the 1.6s timeout period, WDO asserts low. On the next WDI edge (low-to-high or high-to-low), WDO returns high and the timer resets. This behavior is hardwired and unaffected by firmware. Holding WDI static thus generates periodic 200ms reset pulses every 1.6s-providing fail-safe recovery even if µP firmware hangs completely.
What is the purpose of the BATT ON output on the MAX794ESE+, and how is it used?
The BATT ON output on the MAX794ESE+ is an active-high logic signal indicating that the device has switched power delivery from VCC to the backup battery (i.e., OUT is sourced from BATT). It is designed to drive the gate/base of an external PMOS/NPN transistor (e.g., Si9433DY) to handle load currents exceeding the internal switch's 75mA limit. When BATT ON is high, the external switch turns on, augmenting battery current capability while maintaining clean switchover timing.
Does the MAX794ESE+ support operation with VCC lower than 3.0V, and what are the limits?
Yes-the MAX794ESE+ operates with VCC as low as 2.72V (per Absolute Maximum Ratings and Electrical Characteristics tables). Its reset comparator remains functional down to VCC = 1V, guaranteeing reset assertion during deep brownout. However, battery switchover requires VCC > VSW (min 2.55V) to initiate switching, and CE gating performance degrades below 2.8V. For reliable operation across full spec, maintain VCC ≥ 2.85V; for guaranteed reset only, VCC ≥ 1V suffices.
MAX794ESE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- Adjustable/Selectable
- Output:
- Open Drain, Push-Pull
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX794ESE+ FAQ
1.How can I place an order for MAX794ESE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX794ESE+ 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 MAX794ESE+ reliable?
The price and inventory of MAX794ESE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX794ESE+ is usually 5 days.
3.What payment methods are accepted for MAX794ESE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX794ESE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX794ESE+?
MAX794ESE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX794ESE+ 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 MAX794ESE+?
For technical support, including MAX794ESE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX794ESE+ requirements.
6.How does Aetrix verify that MAX794ESE+ is sourced from the original manufacturer or authorized distributors?
All MAX794ESE+ 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 MAX794ESE+ meets industry standards.
7.What is the process for return or replacement of MAX794ESE+?
All MAX794ESE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX794ESE+, 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 MAX794ESE+ part is unused and in its original packaging.
Return procedure for MAX794ESE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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