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Analog Devices Inc./Maxim Integrated MAX791ESE+
- Part No.:
- MAX791ESE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX791ESE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,149
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Product details
Overview
MAX791ESE+ from Maxim Integrated is a microprocessor supervisory circuit designed for power monitoring and battery switchover in embedded systems. It provides precision 4.65V reset threshold, 200ms reset timeout, 250mA VCC-mode output drive, 25mA battery-backup mode output, and integrated watchdog timer with adjustable timeout (1.6s default). It is used in portable/battery-powered equipment requiring reliable reset assertion down to VCC = 1V.
For engineers reviewing the MAX791ESE+ datasheet, MAX791ESE+ pinout, MAX791ESE+ application, or MAX791ESE+ equivalent, key selection criteria include guaranteed reset validity at low VCC, dual-mode power switching (VCC/VBATT), chip-enable gating with 6ns propagation delay, and two-stage power-fail warning via LOWLINE and PFI/PFO.
Technical Context
The MAX791ESE+ integrates a precision voltage monitor (4.65V ±15mV), a low-line comparator (threshold = reset threshold + 150mV), and a programmable watchdog timer using an external capacitor on SWT pin. Its internal PMOS switchover switch connects VOUT to VBATT when VCC falls below both the reset threshold and VBATT, enabling seamless backup power delivery to CMOS RAM or RTCs.
Chip-enable gating operates with 6ns propagation delay (50Ω source, 50pF load) and automatic disable during reset to prevent memory corruption. The manual-reset input (MR) features internal 1.25V threshold detection and 4µs propagation delay to RESET, eliminating need for external pull-up or debouncing components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±15mV - ensures reliable µP reset at nominal +5V supply with margin against brownout |
| Reset Timeout | 200ms typ - guarantees sufficient hold time for processor initialization after power-up |
| VCC Supply Current | 50µA typ - enables use in low-power portable equipment without compromising supervision integrity |
| VCC-to-VOUT On-Resistance | 1.2Ω typ at VCC = 3V - minimizes voltage drop under 250mA load, preserving system rail stability |
| VBATT-to-VOUT On-Resistance | 17Ω typ at VBATT = 2.0V - supports stable 25mA backup current for real-time clocks or SRAM retention |
| Watchdog Timeout | 1.6s nominal (adjustable via SWT capacitor) - provides configurable software fault detection window |
| CE Propagation Delay | 6ns max - allows integration with high-speed µPs without timing violation in memory access paths |
Pinout & Package
MAX791ESE+ is housed in a 16-pin narrow SO (Small Outline) package, RoHS-compliant and lead-free (denoted by '+' suffix), with 1.27mm pitch and standard JEDEC MO-153 footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Connects to external Li-ion, coin cell, or supercapacitor; enables switchover when VCC fails |
| 2 VOUT | Output supply voltage | Switched output tied to VCC or VBATT; powers downstream logic and drives internal comparators |
| 3 VCC | Main supply input | +5V regulated input; powers IC core and determines reset assertion state |
| 4 GND | Ground reference | 0V return for all analog/digital functions; requires low-inductance connection to minimize noise |
| 5 BATT ON | Battery-on status indicator | Open-drain output high when VOUT sourced from VBATT; drives PNP base for >250mA external switching |
| 6 PFO | Power-fail output | Active-low comparator output (1.25V threshold); signals early power degradation independent of reset function |
| 7 PFI | Power-fail input | Non-inverting comparator input; monitors auxiliary supplies (e.g., -12V via divider) or unregulated rails |
| 8 SWT | Watchdog timeout select | Capacitor connection point to set watchdog period (2.1 × CnF ms); must not float or tie to GND |
| 9 MR | Manual-reset input | 1.25V-threshold active-low input; accepts direct pushbutton connection without external components |
| 10 LOWLINE | Low-line comparator output | Active-low output triggered 150mV above reset threshold; generates NMI before full brownout |
| 11 WDI | Watchdog input | Three-level input (high/mid/low); toggling resets watchdog timer; floating disables watchdog |
| 12 CE OUT | Chip-enable output | Gated CE signal; disabled during reset to prevent memory write corruption during power transition |
| 13 CE IN | Chip-enable input | High-impedance when RESET active; series 75Ω resistance in enabled mode matches typical µP CE drive |
| 14 WDO | Watchdog output | Active-low fault indicator asserted 70ns after WDPO pulse; remains low until next WDI transition |
| 15 RESET | Reset output | Active-low open-drain output; sinks 3.2mA @ 0.1V; valid down to VCC = 1V (no battery) or 0V (with battery) |
| 16 WDPO | Watchdog-pulse output | 1ms active-low pulse preceding WDO assertion; used to clock external latch for two-fault shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset monitoring | 4.65V threshold with ±15mV tolerance over -40°C to +85°C ensures consistent reset behavior across industrial temperature range |
| Two-stage power-fail warning | Independent LOWLINE (reset +150mV) and PFI/PFO (1.25V fixed) outputs enable layered response to supply degradation |
| Integrated CE gating | 6ns propagation delay and automatic disable during reset prevent spurious memory writes during power transitions |
| Backup-battery switchover | PMOS-based switch with 17Ω on-resistance at 2.0V VBATT delivers stable 25mA to preserve RTC/CMOS RAM data |
| Adjustable watchdog timer | SWT pin accepts 4.7–100nF capacitor to set timeout from ~10ms to 210ms, supporting diverse firmware execution profiles |
| Guaranteed reset validity | RESET output functional down to VCC = 1V (no battery) or 0V (with VBATT ≥2V), critical for ultra-low-power brownout recovery |
Applications
| Portable Medical Devices | Industrial PLC Controllers |
|---|---|
Use Scenario: Battery-backed ECG monitor operating on Li-ion with intermittent AC charging. IC Role / Device Role / Timing Role: Supervisory circuit providing VCC brownout detection, automatic switchover to backup battery, and watchdog-triggered safe shutdown on firmware hang. Use Value: Ensures continuous real-time clock and patient data retention during AC loss, with 200ms reset hold guaranteeing clean µP restart. |
Use Scenario: DIN-rail mounted controller managing I/O modules in factory automation with 24VDC main supply. IC Role / Device Role / Timing Role: Power supervisor generating NMI via LOWLINE output as 24V rail decays, while RESET holds CPU in known state until safe shutdown sequence completes. Use Value: Prevents corrupted I/O state during undervoltage conditions; 150mV hysteresis on LOWLINE avoids chatter near trip point. |
| Smart Energy Meters | Automotive Infotainment Head Units |
Use Scenario: Revenue-grade meter with supercapacitor backup maintaining timekeeping and tamper logs during grid outage. IC Role / Device Role / Timing Role: Dual-supply supervisor using VBATT switchover and PFI monitoring of auxiliary 3.3V rail to detect early power failure before main 5V collapse. Use Value: 1.25V PFI threshold enables precise detection of secondary supply faults; MaxCap-compatible design supports high-capacity backup storage. |
Use Scenario: Head unit powered from vehicle battery with ignition-controlled 12V supply and internal 5V regulator. IC Role / Device Role / Timing Role: Reset generator asserting RESET during cold-cranking voltage dip (<4.65V), while MR input enables service-mode hard reset via diagnostic port. Use Value: Guaranteed RESET validity down to VCC = 1V prevents undefined µP behavior during cranking; MR threshold immune to automotive noise. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACPE+ | Fixed 4.65V reset, no adjustable watchdog, 100µA supply current, DIP-only packaging | Lacks LOWLINE output and CE gating; suitable only for basic reset-only designs | Select when cost-sensitive, non-battery-backed, and no watchdog or memory protection required |
| TPS3823MPW | 3.08V fixed reset threshold, 200ms timeout, 12µA quiescent current, no battery switchover or CE gating | Designed for low-voltage systems (3.3V/2.5V); no VBATT interface or backup power management | Choose for modern low-voltage µPs where battery backup is handled externally or not needed |
Compared with MAX691ACPE+ and TPS3823MPW, the MAX791ESE+ uniquely combines precision 4.65V reset, battery switchover, CE gating, and dual-stage power-fail warning in a single industrial-temperature SO package-making it irreplaceable for legacy +5V systems requiring robust data retention and fault resilience.
Availability
MAX791ESE+ is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC controllers, smart energy meters, and automotive infotainment head units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX791ESE+ 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 applications.
The MAX791ESE+ belongs to Maxim's microprocessor supervisory product line, engineered specifically for systems demanding guaranteed reset behavior, battery-backed memory retention, and multi-layered power-fail response in harsh environments.
FAQ
What is the operating temperature range for the MAX791ESE+?
The MAX791ESE+ is rated for operation from -40°C to +85°C, meeting industrial temperature requirements. This range is confirmed in the Ordering Information table and validated across all electrical characteristics including reset threshold (±15mV), watchdog timeout, and VCC supply current (50µA typ). The 'E' suffix explicitly denotes this extended temperature grade, distinguishing it from the commercial-grade 'C' version (0°C to +70°C).
Does the MAX791ESE+ support battery switchover, and what are the conditions?
Yes, the MAX791ESE+ supports automatic battery switchover. It switches VOUT from VCC to VBATT when two conditions are met simultaneously: VCC falls below the reset threshold (4.65V) and VCC is also less than VBATT. This is implemented via an internal PMOS switch with 17Ω on-resistance at 2.0V VBATT, enabling up to 25mA continuous backup current to preserve CMOS RAM or RTC data during main supply failure.
How does the watchdog timer on the MAX791ESE+ work, and can its timeout be adjusted?
The MAX791ESE+ watchdog timer asserts WDO and WDPO if the WDI input remains static (high or low) longer than the timeout period. The default timeout is 1.6s, set by connecting SWT to VOUT. To adjust it, connect a capacitor (4.7nF–100nF) between SWT and GND; timeout = 2.1 × CnF ms. Leaving WDI floating disables the watchdog entirely, as its internal 100kΩ bias network sets it to ~1.6V.
What is the purpose of the LOWLINE output on the MAX791ESE+, and how does it differ from RESET?
The LOWLINE output on the MAX791ESE+ is an active-low comparator output triggered when VCC falls to 150mV above the reset threshold (i.e., ~4.80V), providing early warning before full reset assertion. Unlike RESET-which holds the µP in reset for 200ms after recovery-LOWLINE enables nonmaskable interrupt (NMI) generation for graceful firmware shutdown, data save, or alert signaling prior to system halt.
Can the MAX791ESE+ be used with a 3.3V main supply?
No, the MAX791ESE+ is designed for +5V systems. Its reset threshold is fixed at 4.65V, and absolute maximum VCC rating is +6V, but operation below 4.75V violates the specified operating range (VCC = 4.75V to 5.5V per Electrical Characteristics). For 3.3V applications, consider alternatives like the TPS3823MPW (3.08V reset) or MAX6326 (3.08V), which are explicitly characterized for lower supply voltages.
MAX791ESE+ 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:
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX791ESE+ FAQ
1.How can I place an order for MAX791ESE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX791ESE+ 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 MAX791ESE+ reliable?
The price and inventory of MAX791ESE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX791ESE+ is usually 5 days.
3.What payment methods are accepted for MAX791ESE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX791ESE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX791ESE+?
MAX791ESE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX791ESE+ 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 MAX791ESE+?
For technical support, including MAX791ESE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX791ESE+ requirements.
6.How does Aetrix verify that MAX791ESE+ is sourced from the original manufacturer or authorized distributors?
All MAX791ESE+ 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 MAX791ESE+ meets industry standards.
7.What is the process for return or replacement of MAX791ESE+?
All MAX791ESE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX791ESE+, 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 MAX791ESE+ part is unused and in its original packaging.
Return procedure for MAX791ESE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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