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Analog Devices Inc./Maxim Integrated MAX791CUE+
- Part No.:
- MAX791CUE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
MAX791CUE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:959
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Product details
Overview
MAX791CUE+ 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, features adjustable watchdog timeout (1–250ms), and supports chip-enable gating for CMOS RAM protection in portable and industrial embedded systems.
For engineers reviewing the MAX791CUE+ datasheet, MAX791CUE+ pinout, MAX791CUE+ application, or MAX791CUE+ equivalent, this page delivers verified functional identity, validated 16-pin TSSOP package mapping, confirmed reset threshold (4.65V), battery switchover behavior, and two documented alternative supervisory ICs with explicit technical and application differences.
Technical Context
The MAX791CUE+ integrates a precision 4.65V reset comparator with 15mV hysteresis, a separate low-line comparator set 150mV above reset threshold, and a dual-mode watchdog timer with preset 1.6s timeout or capacitor-adjustable range (4.7–100nF → 10–210ms). Its internal PMOS switchover path enables seamless transition between VCC and VBATT supplies.
Chip-enable gating uses a transmission gate with 6ns propagation delay (50Ω source, 50pF load) and 75Ω on-resistance; the BATT ON output drives external PNP transistors for >250mA backup loads. All outputs are VOUT-referenced, ensuring valid logic levels during battery-backup mode when VCC = 0V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±15mV - guarantees reliable µP reset initiation at nominal +5V rail collapse |
| Reset Timeout Delay | 200ms typ - ensures stable power-up before code execution resumes |
| VCC-to-VOUT On-Resistance | 1.2Ω typ at 3V - minimizes dropout and power loss during main supply operation |
| VBATT-to-VOUT On-Resistance | 17Ω typ at 2.0V - enables efficient low-voltage battery backup for real-time clocks and RAM |
| Supply Current (Normal Mode) | 50µA typ - extends battery life in portable equipment without compromising supervision speed |
| Watchdog Timeout Range | 1.6s fixed or 10–210ms adjustable via SWT capacitor - supports both default safety timing and custom firmware watchdog intervals |
| CE Propagation Delay | 6ns max - preserves high-speed memory access integrity during power transitions |
| RESET Validity Limit | VCC ≥ 1V - maintains reset assertion even during deep brownout, critical for fail-safe shutdown |
Pinout & Package
MAX791CUE+ is housed in a 16-pin TSSOP (Thin Shrink Small Outline Package) with 0.65mm pitch, JEDEC MO-153 compliant, lead-free (RoHS), and rated for 0°C to +70°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Connects to external Li-ion, coin cell, or supercap; enables switchover when VCC falls below reset threshold and VBATT > VCC |
| 2 VOUT | Output supply voltage | Switched output tied to VCC or VBATT; powers RESET, CE OUT, WDO, WDPO, and LOWLINE internally |
| 3 VCC | +5V main supply input | Primary power rail monitored for reset; must be ≥4.65V for normal operation |
| 4 GND | Ground reference | 0V return for all analog comparators, digital outputs, and internal biasing networks |
| 5 BATT ON | Battery-on status indicator | Open-drain output pulled high by VOUT; signals active battery-backup mode for external driver control |
| 6 PFO | Power-fail output | Active-low uncommitted comparator output; asserts when PFI < 1.25V, usable for NMI or system-level warning |
| 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 | Connect to VOUT for 1.6s default; connect capacitor to GND for adjustable timeout (2.1 × CnF ms) |
| 9 MR | Manual-reset input | Active-low TTL/CMOS-compatible input; 15µs minimum pulse width required to trigger full reset sequence |
| 10 LOWLINE | Low-line warning output | Active-low comparator output triggered at VCC = 4.80V (4.65V + 150mV); generates NMI before reset assertion |
| 11 WDI | Watchdog input | Three-level input (high/mid/low); toggling within timeout period resets watchdog; floating disables function |
| 12 CE OUT | Chip-enable output | Gated CE signal; disabled during reset to prevent memory corruption; 6ns propagation delay preserves timing margins |
| 13 CE IN | Chip-enable input | High-impedance when RESET active; 75Ω series resistance in enabled mode matches standard memory interface drive |
| 14 WDO | Watchdog output | Active-low fault indicator; remains low until next WDI transition after timeout; high during battery-backup mode |
| 15 RESET | Reset output | Active-low open-drain output; sinks 3.2mA at 0.1V; guaranteed valid down to VCC = 1V with external 10kΩ pull-down |
| 16 WDPO | Watchdog-pulse output | 1ms active-low pulse preceding WDO by 70ns; used to clock external latch for two-fault shutdown sequencing |
Key Features
| Feature | Design Value |
|---|---|
| Two-stage power-fail detection | Independent LOWLINE comparator (4.80V threshold) provides early warning 150mV above RESET threshold (4.65V), enabling NMI-triggered graceful shutdown before reset |
| VOUT-referenced outputs | All digital outputs (RESET, WDO, WDPO, CE OUT, LOWLINE, PFO, BATT ON) tie to VOUT-not VCC-ensuring correct logic levels and drive strength during battery-backup mode (VCC = 0V) |
| Software-monitored battery voltage | PFI input allows µP to read VBATT via ADC using resistor divider; combined with PFO, enables programmable low-battery alerts and charge management |
| Write-protection gating | CE IN/CE OUT transmission gate blocks memory writes during power failure or reset, preventing data corruption in CMOS RAM or EEPROM without external logic |
| MaxCap®/SuperCap® compatibility | Internal switchover circuitry supports high-capacitance backup sources (e.g., 0.47F) with controlled inrush and low on-resistance (<17Ω), eliminating need for external diodes or MOSFETs |
| Guaranteed reset validity to 1V | RESET output remains asserted and electrically valid (≤0.4V saturation with 10kΩ pull-down) even as VCC collapses to 1V, ensuring deterministic µP halt during brownout |
Applications
| Portable Medical Devices | Industrial PLC Controllers |
|---|---|
Use Scenario: Battery-powered glucose meters and handheld diagnostic tools requiring fail-safe shutdown during low-battery or supply sag. IC Role / Device Role / Timing Role: Supervisory circuit providing VCC monitoring, manual reset, battery switchover, and watchdog-triggered data save before power loss. Use Value: 50µA quiescent current extends single-cell CR2032 life beyond 5 years; 1V reset validity prevents erratic behavior during final battery discharge. |
Use Scenario: DIN-rail mounted programmable logic controllers operating in harsh factory environments with fluctuating 24VDC supplies. IC Role / Device Role / Timing Role: Dual-supply supervisor managing primary 5V rail and backup supercap, with LOWLINE NMI for predictive maintenance alerts. Use Value: 250mA VCC-mode output drives multiple isolation buffers; 150mV low-line hysteresis rejects noise while detecting true undervoltage events. |
| Smart Energy Meters | Embedded Network Routers |
Use Scenario: ANSI C12.20-compliant electricity meters with tamper detection, real-time clock, and flash memory logging. IC Role / Device Role / Timing Role: Power monitor coordinating RTC backup, EEPROM write-protection, and secure boot reset sequencing during AC mains dropout. Use Value: CE gating prevents partial writes during brownout; WDPO-driven D-flip-flop latches two consecutive faults to disable RF transmission during unsafe states. |
Use Scenario: Carrier-class Ethernet routers with redundant power inputs and persistent configuration storage. IC Role / Device Role / Timing Role: System-level supervisor verifying 5V rail stability, asserting reset on PFI-detected PoE voltage sag, and protecting DDR SDRAM initialization. Use Value: 6ns CE propagation delay meets DDR2/3 timing budgets; PFI comparator monitors auxiliary 3.3V LDO for secondary fault detection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6326UT46D3+ | Single-function 4.63V reset IC; no watchdog, no CE gating, no battery switchover; 1.6µA supply current | Suitable only for basic reset-only applications; lacks MAX791CUE+'s multi-function integration for RAM backup and fault escalation | Select when cost and footprint are critical and only reset supervision is needed-no battery or watchdog functionality required |
| TPS3808G33DBVR | 3.3V-specific supervisor; 200ms reset delay; no battery switchover; no CE gating; 16-pin WSON package | Designed for 3.3V systems only; incompatible with 5V VCC monitoring or VBATT backup paths of MAX791CUE+ | Choose for new 3.3V designs where MAX791CUE+'s 5V focus and dual-supply architecture are unnecessary |
Compared with MAX6326UT46D3+ and TPS3808G33DBVR, the MAX791CUE+ uniquely combines 5V reset supervision, battery-backed RAM support, adjustable watchdog, and CE signal gating in one 16-pin TSSOP-making it irreplaceable in portable or industrial systems requiring coordinated power-fail response and data integrity assurance.
Availability
MAX791CUE+ is available at Aetrix Electronics and suitable for portable medical devices, industrial PLC controllers, smart energy meters, and embedded network routers requiring stable component supply across extended temperature and lifecycle requirements.
Supply support for MAX791CUE+ 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 markets.
The MAX791 product line delivers integrated microprocessor supervision with battery switchover, watchdog, and memory protection-designed specifically for portable, battery-backed, and mission-critical embedded systems demanding reliability under voltage stress.
FAQ
What is the exact reset threshold voltage of the MAX791CUE+ and how does it vary with temperature?
The MAX791CUE+ has a nominal reset threshold of 4.65V with ±15mV tolerance over temperature. According to the datasheet's Typical Operating Characteristics graph (Figure MAX791-07), the threshold drifts less than ±5mV from –40°C to +85°C, and remains within 4.60V–4.70V across its specified 0°C to +70°C operating range. This tight stability ensures consistent reset behavior in thermally varying environments without external calibration.
Can the MAX791CUE+ operate without a backup battery connected to VBATT?
Yes, the MAX791CUE+ functions fully without a battery on VBATT. The RESET output remains guaranteed down to VCC = 1V, and all supervision features-including power-on reset, manual reset, watchdog, and LOWLINE-operate normally. The battery switchover path is disabled when VBATT ≤ VCC – 1V, and the device draws only 50µA from VCC in normal mode. No external components are required for battery-less operation.
How is the watchdog timeout period adjusted on the MAX791CUE+ and what is the valid capacitor range?
The MAX791CUE+ watchdog timeout is adjusted by connecting a capacitor from the SWT pin to GND. The timeout follows the formula: 2.1 × CnF ms. Valid capacitor values range from 4.7nF (10ms timeout) to 100nF (210ms timeout), as verified in the Watchdog Timeout vs. Timing Capacitor graph (Figure MAX791-11). Connecting SWT to VOUT selects the default 1.6s timeout; leaving SWT floating is prohibited and may cause undefined behavior.
What is the purpose of the CE IN and CE OUT pins on the MAX791CUE+, and how do they protect memory?
The CE IN and CE OUT pins implement hardware-enforced chip-enable gating. During normal operation, CE IN passes directly to CE OUT with 6ns delay. When RESET is asserted-due to power failure, brownout, or manual reset-the CE path is disabled, forcing CE OUT high (VOUT-referenced) and blocking memory writes. This prevents partial or corrupted writes to CMOS RAM or EEPROM during unstable power conditions, eliminating the need for software-based write-protection schemes.
Does the MAX791CUE+ support negative voltage monitoring, and if so, how is it implemented?
Yes, the MAX791CUE+ supports negative voltage monitoring via the PFI (Power-Fail Input) pin, which is an uncommitted comparator input with 1.25V threshold. To monitor a negative rail like –12V, connect PFI to ground through a resistor divider that scales the negative voltage to a positive voltage at PFI. For example, a 120kΩ–10kΩ divider converts –12V to +1.0V at PFI, triggering PFO when the negative rail sags below –10.2V. The PFI input leakage is ±25nA, ensuring minimal loading on the divider network.
MAX791CUE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
MAX791CUE+ FAQ
1.How can I place an order for MAX791CUE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX791CUE+ 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 MAX791CUE+ reliable?
The price and inventory of MAX791CUE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX791CUE+ is usually 5 days.
3.What payment methods are accepted for MAX791CUE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX791CUE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX791CUE+?
MAX791CUE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX791CUE+ 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 MAX791CUE+?
For technical support, including MAX791CUE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX791CUE+ requirements.
6.How does Aetrix verify that MAX791CUE+ is sourced from the original manufacturer or authorized distributors?
All MAX791CUE+ 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 MAX791CUE+ meets industry standards.
7.What is the process for return or replacement of MAX791CUE+?
All MAX791CUE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX791CUE+, 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 MAX791CUE+ part is unused and in its original packaging.
Return procedure for MAX791CUE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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