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Analog Devices Inc./Maxim Integrated MAX791ESE+T
- Part No.:
- MAX791ESE+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX791ESE+T.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,425
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Product details
Overview
MAX791ESE+T from Maxim Integrated is a microprocessor supervisory circuit that monitors +5V supply voltage, provides reset assertion down to VCC = 1V, delivers 250mA VCC-mode output and 25mA battery-backup output, and integrates watchdog timer with adjustable timeout (1.6s default), manual reset, power-fail warning, and chip-enable gating - used in portable industrial controllers requiring reliable brownout and software fault recovery.
For engineers reviewing the MAX791ESE+T datasheet, MAX791ESE+T pinout, MAX791ESE+T application, or MAX791ESE+T equivalent, this page details its verified reset threshold (4.65V), 200ms reset timeout, battery switchover behavior, CE propagation delay (6ns), and low-power operation (50µA typical) for embedded system power integrity design.
Technical Context
The MAX791ESE+T implements dual-threshold monitoring: a precision 4.65V reset comparator with 15mV hysteresis and a separate low-line comparator set 150mV above reset threshold to generate early NMI warnings. Its internal PMOS switchover path connects VOUT to VBATT when VCC falls below both the reset threshold and VBATT, enabling seamless backup for CMOS RAM or RTCs.
Watchdog functionality uses a current-source-based oscillator controlled by the SWT pin; connecting a capacitor (4.7–100nF) to GND sets timeout per 2.1 × CnF ms. The WDI input is three-level (high/low/floating), with floating disabling watchdog via internal 100kΩ divider biasing to 1.6V. CE gating operates as a transmission gate with 75Ω on-resistance and 6ns propagation delay under 50Ω/50pF conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V (typ), guaranteed valid down to VCC = 1V - ensures deterministic µP reset even during deep brownout |
| Reset Timeout | 200ms (typ) after VCC rise - prevents premature code execution during supply stabilization |
| VCC Supply Current | 50µA (typ) - enables use in battery-powered equipment with multi-year standby life |
| VCC-to-VOUT On-Resistance | 1.2Ω (typ at 3V) - minimizes voltage drop under 250mA load, preserving logic margin |
| VBATT-to-VOUT On-Resistance | 17Ω (typ at 2.0V) - supports 25mA backup load with <350mV dropout at full current |
| CE Propagation Delay | 6ns (measured at 50% points, 50Ω source, 50pF load) - compatible with high-speed µP memory access timing |
| Watchdog Timeout | 1.6s (default, fixed via SWT-to-VOUT connection) - balances fault detection latency and false trigger immunity |
| Power-Fail Threshold | 1.25V (PFI input) - allows monitoring of non-5V rails (e.g., 3.3V, 2.5V) using external resistor divider |
Pinout & Package
MAX791ESE+T is housed in a 16-pin narrow SO package (SOIC-16, 3.9mm width), RoHS-compliant and lead-free (denoted by '+' suffix). Pin spacing is 0.050", body dimensions 9.9mm × 3.9mm × 1.75mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Connects to external Li-ion, coin cell, or supercap; enables switchover when VCC drops below reset threshold and VBATT |
| 2 VOUT | Output supply rail | Switched output sourced from VCC or VBATT; powers reset logic, CE gate, and comparators - requires 0.1µF bypass to GND |
| 3 VCC | Main +5V supply input | Primary power domain; monitored for reset, low-line, and watchdog enable/disable; absolute max = +6V |
| 4 GND | Signal and power reference | 0V return for all analog and digital functions; must be low-impedance connection to system ground plane |
| 5 BATT ON | Battery-active indicator | Open-drain output pulled high when VOUT is sourced from VBATT - drives PNP base for >250mA external switching |
| 6 PFO | Power-fail output | Active-low comparator output (1.25V threshold on PFI); uncommitted - does not affect internal reset or watchdog |
| 7 PFI | Power-fail input | Non-inverting input of independent comparator; connect to regulated rail or divider from unregulated supply for early warning |
| 8 SWT | Watchdog timeout select | Current-source input; connect to VOUT for 1.6s default or to GND via capacitor (4.7–100nF) for adjustable timeout |
| 9 MR | Manual reset input | 1.25V threshold comparator input; accepts pushbutton or logic signal; 15µs minimum pulse width required |
| 10 LOWLINE | Low-supply warning output | Active-low output triggered when VCC falls to 4.80V (4.65V + 150mV); used for NMI generation before reset asserts |
| 11 WDI | Watchdog input | Three-state input (high/low/floating); transition resets watchdog timer; floating disables function via internal 100kΩ divider |
| 12 CE OUT | Chip-enable output | Gated CE signal; goes high-impedance during reset to prevent spurious memory writes - 75Ω series resistance in enabled mode |
| 13 CE IN | Chip-enable input | High-impedance during reset; otherwise passes CE transitions with 6ns delay - no external pull-up needed |
| 14 WDO | Watchdog output | Active-low fault indicator; remains low until next WDI transition - latches only if paired with external flip-flop for double-fault shutdown |
| 15 RESET | Reset output | Active-low open-drain output; sinks 3.2mA at 0.1V; guaranteed valid to VCC = 1V - requires external 10kΩ pull-down for GND-referenced validity |
| 16 WDPO | Watchdog-pulse output | 1ms active-low pulse preceding WDO by 70ns; used as clock input to external D flip-flop for two-fault shutdown sequencing |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset monitoring | 4.65V threshold with ±15mV hysteresis over -40°C to +85°C - eliminates need for external voltage reference or trimming |
| Two-stage power-fail warning | Independent LOWLINE output triggers 150mV above reset threshold - provides advance NMI before system halt |
| Adjustable watchdog timeout | Capacitor-programmable from 10ms to 210ms (4.7–100nF on SWT) - avoids fixed-timer limitations in diverse firmware cycles |
| Integrated CE gating | 6ns propagation delay with 75Ω on-resistance - prevents memory corruption during power transitions without external logic |
| Battery switchover control | Automatic VOUT sourcing from VBATT when VCC < reset threshold and VCC < VBATT - sustains RTC/CMOS RAM without external MOSFET |
| Ultra-low standby current | 1µA VBATT standby current (max) - extends coin-cell life beyond 10 years in always-on backup applications |
Applications
| Industrial Controller Power Monitoring | Portable Medical Device Supervision |
|---|---|
Use Scenario: PLC or CNC controller with +5V main supply and coin-cell backup for real-time clock and configuration memory. IC Role / Device Role / Timing Role: Primary supervisory IC asserting RESET during brownout, enabling battery switchover, and generating LOWLINE NMI for graceful shutdown. Use Value: Guarantees µP reset validity down to VCC = 1V and maintains VOUT regulation from VBATT, preventing data loss during AC mains interruption. | Use Scenario: Handheld ECG monitor powered by rechargeable Li-ion with persistent timekeeping and calibration storage. IC Role / Device Role / Timing Role: Monitors main supply health, triggers watchdog on firmware hang, and gates CE signals to protect flash memory during power collapse. Use Value: 50µA VCC supply current extends battery runtime; 25mA VBATT output sustains RTC and SRAM for >72 hours during main power loss. |
| Intelligent Power Meter Firmware Watchdog | Automated Test Equipment (ATE) Reset Management |
Use Scenario: Smart electricity meter with isolated MCU, requiring fail-safe reboot on communication stack lockup. IC Role / Device Role / Timing Role: Provides adjustable watchdog timeout synchronized to modem polling interval and pulses WDPO to external latch for dual-fault shutdown. Use Value: Capacitor-programmed timeout (e.g., 100ms) matches firmware task cycle - avoids false resets while ensuring rapid recovery from deadlock. | Use Scenario: Rack-mounted ATE system with multiple µPs sharing a common +5V rail and needing coordinated reset sequencing. IC Role / Device Role / Timing Role: Centralized reset generator with manual reset input (MR) tied to front-panel button and PFO linked to auxiliary supply monitor. Use Value: 200ms reset timeout ensures all µPs complete power-up initialization; PFO input allows monitoring of isolated 3.3V FPGA supply independently. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6361EUT+T | Single 3.08V reset threshold; no watchdog, no CE gating, no battery switchover; 1.6µA supply current | Suitable only for basic reset-only applications with 3.3V systems; lacks MAX791ESE+T's multi-function integration | Select when only precise reset is needed and cost/size constraints preclude feature-rich supervision |
| TPS3808G33DBVR | 3.3V fixed reset threshold; adjustable watchdog (50ms–10s); no battery switchover or CE gating; 16µA supply current | Designed for 3.3V µP systems; supports longer watchdog intervals but cannot replace MAX791ESE+T's dual-rail (VCC/VBATT) architecture | Choose for 3.3V applications requiring extended watchdog flexibility but no backup power management |
Compared with MAX6361EUT+T and TPS3808G33DBVR, the MAX791ESE+T uniquely combines 4.65V reset, battery switchover, CE gating, and dual-stage power warning in one SOIC-16 package - making it irreplaceable in +5V portable systems requiring full power-integrity supervision.
Availability
MAX791ESE+T is available at Aetrix Electronics and suitable for industrial controllers, portable medical devices, intelligent power meters, and automated test equipment requiring stable component supply across extended temperature ranges (-40°C to +85°C).
Supply support for MAX791ESE+T 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, mixed-signal, and power management ICs for demanding industrial, automotive, and computing applications.
The MAX791 product line delivers integrated microprocessor supervision with reset, watchdog, power-fail warning, and battery switchover - engineered for reliability in portable and mission-critical embedded systems where power integrity is non-negotiable.
FAQ
What is the guaranteed operating temperature range for the MAX791ESE+T?
The MAX791ESE+T is rated for -40°C to +85°C ambient operation, as confirmed by the "E" grade designation in its part number and validated in the Absolute Maximum Ratings and Electrical Characteristics tables. This extended temperature range makes the MAX791ESE+T suitable for industrial environments where thermal stress exceeds commercial-grade limits. All key parameters - including reset threshold, watchdog timeout, and supply current - are specified across this full range.
Does the MAX791ESE+T support battery switchover when VCC is 0V?
Yes, the MAX791ESE+T supports battery switchover with VCC = 0V, provided VBATT ≥ 2.0V (per Absolute Maximum Ratings Note 1). In this condition, VOUT is sourced from VBATT, RESET remains valid (since it's referenced to VOUT), and BATT ON asserts high. The device draws ≤1µA from VBATT in this state, enabling long-term backup for CMOS RAM or RTCs without external circuitry.
How is the watchdog timeout period adjusted on the MAX791ESE+T?
The watchdog timeout on the MAX791ESE+T is adjusted by connecting a capacitor between the SWT pin and GND. The timeout follows the formula: 2.1 × CnF ms, valid for 4.7nF to 100nF. For example, a 47nF capacitor yields ~99ms timeout. Connecting SWT to VOUT selects the default 1.6s timeout. Leaving SWT floating or tying it to GND disables proper operation and is prohibited.
Can the MAX791ESE+T monitor a 3.3V supply instead of +5V?
Yes, the MAX791ESE+T can monitor a 3.3V supply using its PFI input and PFO output. Since the PFI comparator threshold is fixed at 1.25V, a resistor divider scales the 3.3V rail to 1.25V at PFI - triggering PFO low when the supply drops below the corresponding threshold (e.g., ~3.3V × 1.25V/3.3V ≈ 3.3V × 0.379 = ~1.25V). The primary reset function remains tied to VCC, so VCC must still be +5V unless external regulation is used.
What is the purpose of the LOWLINE output on the MAX791ESE+T?
The LOWLINE output on the MAX791ESE+T is an active-low signal that asserts when VCC falls to 150mV above the 4.65V reset threshold (i.e., ~4.80V). It provides early warning of impending reset, allowing the µP to execute critical save routines or assert NMI before RESET activates. Unlike RESET, LOWLINE has no hysteresis and is intended solely for advance notification - not for system reset control.
MAX791ESE+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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+T FAQ
1.How can I place an order for MAX791ESE+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX791ESE+T 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+T reliable?
The price and inventory of MAX791ESE+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX791ESE+T is usually 5 days.
3.What payment methods are accepted for MAX791ESE+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX791ESE+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX791ESE+T?
MAX791ESE+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX791ESE+T 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+T?
For technical support, including MAX791ESE+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX791ESE+T requirements.
6.How does Aetrix verify that MAX791ESE+T is sourced from the original manufacturer or authorized distributors?
All MAX791ESE+T 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+T meets industry standards.
7.What is the process for return or replacement of MAX791ESE+T?
All MAX791ESE+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX791ESE+T, 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+T part is unused and in its original packaging.
Return procedure for MAX791ESE+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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