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Analog Devices Inc./Maxim Integrated MAX791CSE
- Part No.:
- MAX791CSE
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX791CSE.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,470
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Product details
Overview
MAX791CSE from Maxim Integrated is a microprocessor supervisory circuit providing precision 4.65V reset monitoring, 200ms reset timeout, dual-stage power-fail warning (PFI/LOWLINE), battery switchover (25mA backup mode), and adjustable watchdog timer - all in a 16-pin narrow SO package. It ensures reliable µP reset during power-up, brownout, and VCC drop to 1V, with CE gating for memory write-cycle completion in portable and industrial control systems.
For engineers reviewing the MAX791CSE datasheet, MAX791CSE pinout, MAX791CSE application, or MAX791CSE equivalent, this page delivers verified functional specifications, validated pin roles, confirmed battery-backup behavior, exact watchdog timing dependencies on SWT capacitance, and real-world use cases in critical µP power monitoring and intelligent instrumentation.
Technical Context
The MAX791CSE integrates a precision 4.65V reset comparator with 15mV hysteresis, a separate 4.80V low-line comparator (150mV above reset threshold), and an independent 1.25V PFI comparator for flexible power-fail detection. Its internal PMOS switchover path supports seamless transition from VCC to VBATT when VCC falls below both the reset threshold and VBATT.
Watchdog functionality uses a current-source-based oscillator tied to the SWT pin, enabling programmable timeout periods from 10ms to 210ms via external capacitor (4.7–100nF). CE gating operates as a transmission gate with 6ns propagation delay (50Ω source, 50pF load) and 75Ω on-resistance, actively disabling CE OUT during reset assertion to prevent memory corruption.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±15mV - guarantees deterministic µP reset initiation at nominal +5V rail collapse |
| Reset Timeout | 200ms typ - ensures full µP initialization before release from reset state |
| VCC Supply Current | 50µA typ - enables long battery life in portable equipment with no compromise on supervision fidelity |
| Battery-Backup Output | 25mA continuous - sustains CMOS RAM or RTC operation during main supply failure |
| CE Propagation Delay | 6ns max - preserves high-speed memory access timing integrity during normal operation |
| Watchdog Timeout Range | 10ms–210ms - selectable via 4.7–100nF capacitor on SWT pin for software fault detection tuning |
| Low-Line Threshold | 4.80V (4.65V + 150mV) - provides early NMI warning before reset assertion for graceful shutdown |
| VBATT Standby Current | 1µA max - minimizes battery drain during extended backup operation |
Pinout & Package
MAX791CSE is housed in a 16-pin narrow SO (Small Outline) package, 3.9mm width, compliant with JEDEC MS-012AC, with gull-wing leads and standard 1.27mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Connects to external battery/capacitor; powers VOUT when VCC fails and enables switchover logic |
| 2 VOUT | Output supply voltage | Switched output delivering either VCC or VBATT; requires 0.1µF decoupling to GND |
| 3 VCC | Main supply input | +5V regulated input; monitored for reset, LOWLINE, and switchover decisions |
| 4 GND | Ground reference | 0V return for all analog comparators, digital outputs, and internal biasing |
| 5 BATT ON | Battery-on status indicator | Open-drain output asserted high when VOUT is sourced from VBATT - used to drive PNP switch for >250mA loads |
| 6 PFO | Power-fail output | Active-low comparator output tied to PFI; sinks 3.2mA at 0.1V - signals external supply collapse |
| 7 PFI | Power-fail input | Noninverting input of uncommitted comparator; threshold = 1.25V - monitors auxiliary supplies or unregulated rails |
| 8 SWT | Set watchdog timeout | Current-source input controlling watchdog period; connect capacitor to GND for custom timeout (2.1 × CnF ms) |
| 9 MR | Manual-reset input | 1.25V-threshold active-low input; resets internal timers and asserts RESET for ≥15µs pulse width |
| 10 LOWLINE | Low-line comparator output | Active-low output asserting at VCC = 4.80V; provides early NMI before reset for controlled shutdown |
| 11 WDI | Watchdog input | Three-level input (high/mid/low); toggling required within timeout period to prevent WDO/WDPO assertion |
| 12 CE OUT | Chip-enable output | Gated CE signal; goes high-impedance during reset to block spurious memory writes |
| 13 CE IN | Chip-enable input | High-impedance during reset; 75Ω series resistance in enabled mode - interfaces directly with µP CE |
| 14 WDO | Watchdog output | Active-low fault indicator; remains low until next WDI transition after timeout - used for system-level fault recovery |
| 15 RESET | Reset output | Active-low open-drain output; guaranteed valid down to VCC = 1V - drives µP reset with 3.2mA sink capability |
| 16 WDPO | Watchdog-pulse output | 1ms active-low pulse preceding WDO by 70ns - clocks external flip-flop for two-fault latching shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Precision reset monitoring | 4.65V threshold with ±15mV tolerance over 0°C to +70°C - eliminates need for external resistor divider calibration |
| Dual-stage power-fail warning | Independent LOWLINE (4.80V) and PFI (1.25V) comparators - enables both early warning and secondary supply monitoring |
| Adjustable watchdog timer | Timeout set by external capacitor on SWT pin (4.7–100nF) - supports software validation across diverse execution cycles |
| Battery switchover with status flag | Automatic VCC→VBATT transition plus BATT ON output - simplifies backup power management without external logic |
| Memory write-cycle protection | 6ns CE gating with automatic disable during reset - prevents partial writes to CMOS RAM during power instability |
| Guaranteed reset validity to 1V | RESET output functional with VCC ≥1V (no battery) - ensures fail-safe behavior even under severe brownout |
Applications
| Computers | Critical µP Power Monitoring |
|---|---|
Use Scenario: Desktop motherboard power sequencing with +5V rail supervision and NMI-based graceful shutdown. IC Role / Device Role / Timing Role: Primary reset generator and low-line interrupt source; asserts RESET at 4.65V and LOWLINE at 4.80V. Use Value: Prevents data corruption during AC dropout by triggering OS-level save routines 150mV before reset activation. | Use Scenario: Industrial PLC controller requiring guaranteed boot integrity after brownout events. IC Role / Device Role / Timing Role: Supervisory hub managing reset, watchdog, and battery-backed RTC power. Use Value: Maintains RTC time and RAM contents via 25mA VBATT path while asserting RESET until VCC stabilizes for 200ms. |
| Intelligent Instruments | Portable/Battery-Powered Equipment |
Use Scenario: Handheld multimeter with EEPROM configuration storage and auto-power-off. IC Role / Device Role / Timing Role: Memory write protector and watchdog supervisor; gates CE during power transitions. Use Value: Ensures EEPROM write completion before power loss using 6ns CE propagation and 200ms reset hold time. | Use Scenario: Portable medical sensor logging vital signs to flash memory on lithium coin cell. IC Role / Device Role / Timing Role: Low-quiescent supervisor enabling 50µA VCC operation and 1µA VBATT standby. Use Value: Extends battery life >2 years in sleep mode while maintaining instant wake-up readiness and 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 |
|---|---|---|---|
| MAX691CSE | No watchdog function; fixed 200ms reset timeout; lacks CE gating and LOWLINE output | Suitable only for basic reset-only systems without software fault detection or memory write protection | Select MAX691CSE only if watchdog, CE control, and dual-stage warning are unnecessary |
| TPS3823DBVR | Single 3.08V reset threshold; no battery switchover; no PFI/LOWLINE comparators; 350ms min reset timeout | Designed for fixed-voltage embedded systems without backup power or multi-rail monitoring | Choose TPS3823DBVR for cost-sensitive +3.3V applications where battery backup and flexible thresholds are not required |
Compared with MAX691CSE and TPS3823DBVR, the MAX791CSE uniquely combines precision 4.65V reset, adjustable watchdog, battery switchover, and dual-comparator power-fail warning in one narrow SO package - making it irreplaceable for portable and industrial µP systems demanding comprehensive power supervision.
Availability
MAX791CSE is available at Aetrix Electronics and suitable for critical µP power monitoring, intelligent instrumentation, portable/battery-powered equipment, industrial controllers, and computer motherboards requiring stable component supply and long-term lifecycle support.
Supply support for MAX791CSE 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 power management, sensing, and interface applications in industrial, automotive, and computing markets.
The MAX791 product line delivers integrated microprocessor supervisory functions - including reset generation, watchdog timing, battery switchover, and multi-rail power-fail detection - specifically for systems requiring robust, low-power, and space-constrained power supervision.
FAQ
What is the guaranteed minimum reset timeout duration for the MAX791CSE?
The MAX791CSE guarantees a minimum reset timeout of 140ms and a typical value of 200ms after VCC rises above the 4.65V threshold or after manual reset release. This duration ensures sufficient time for power supply stabilization and µP internal initialization before releasing the reset signal. The MAX791CSE reset timeout is internally generated and temperature-compensated, maintaining consistency across its 0°C to +70°C operating range.
Can the MAX791CSE operate without a backup battery connected?
Yes, the MAX791CSE operates fully without a backup battery. Its RESET output remains valid down to VCC = 1V, and all supervision functions - including reset assertion, LOWLINE warning, PFI comparison, and watchdog timing - function normally with only VCC applied. The battery-related features (VBATT input, VOUT switchover, BATT ON flag) are simply inactive when VBATT is unconnected or at 0V.
How does the MAX791CSE handle chip-enable (CE) gating during power-down?
During power-down, when VCC crosses the 4.65V reset threshold, the MAX791CSE disables the CE transmission gate within 15µs, forcing CE OUT high-impedance. This prevents spurious memory writes during unstable supply conditions. CE IN also enters high-impedance mode, limiting leakage to ±1µA. The MAX791CSE resumes CE pass-through only after VCC stabilizes above threshold and the 200ms reset timeout completes.
What is the maximum recommended capacitor value for the SWT pin to achieve longest watchdog timeout on MAX791CSE?
The MAX791CSE supports a maximum SWT capacitor of 100nF, yielding a watchdog timeout of 210ms (2.1 × 100). Exceeding 100nF violates the specified operating range and may cause timing inaccuracy or failure to trigger. The device's internal ±100nA current source is characterized only for 4.7–100nF; values outside this range are not guaranteed. For timeouts beyond 210ms, external timing circuitry must be used instead of relying on the MAX791CSE's built-in watchdog.
Does the MAX791CSE provide any protection against false reset assertion during fast VCC transients?
Yes, the MAX791CSE incorporates hysteresis in both its primary reset comparator (15mV) and LOWLINE comparator (15mV), preventing chatter during noisy or slowly recovering VCC edges. Additionally, its internal reset timeout circuit enforces a minimum 140ms deassertion delay after VCC exceeds threshold, ensuring transient spikes do not prematurely release reset. These features make the MAX791CSE robust against typical power rail noise encountered in industrial and portable environments.
MAX791CSE 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:
- Obsolete
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX791CSE FAQ
1.How can I place an order for MAX791CSE through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX791CSE 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 MAX791CSE reliable?
The price and inventory of MAX791CSE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX791CSE is usually 5 days.
3.What payment methods are accepted for MAX791CSE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX791CSE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX791CSE?
MAX791CSE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX791CSE 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 MAX791CSE?
For technical support, including MAX791CSE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX791CSE requirements.
6.How does Aetrix verify that MAX791CSE is sourced from the original manufacturer or authorized distributors?
All MAX791CSE 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 MAX791CSE meets industry standards.
7.What is the process for return or replacement of MAX791CSE?
All MAX791CSE units undergo pre-shipment inspection (PSI). If there is an issue with MAX791CSE, 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 MAX791CSE part is unused and in its original packaging.
Return procedure for MAX791CSE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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