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Analog Devices Inc./Maxim Integrated MAX791CPE+
- Part No.:
- MAX791CPE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX791CPE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:212
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Product details
Overview
MAX791CPE+ 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, implements a 1.6s (adjustable) watchdog timer, and supports chip-enable gating with 6ns propagation delay - used in portable/battery-powered µP systems requiring reliable power-fail warning and CMOS RAM backup.
For engineers reviewing the MAX791CPE+ datasheet, MAX791CPE+ pinout, MAX791CPE+ application, or MAX791CPE+ equivalent, this page details its verified reset threshold (4.65V), battery switchover behavior, dual-stage power-fail detection, manual-reset timing (15µs min pulse), and CE-gating functionality for memory write-cycle completion in embedded control and intelligent instrumentation.
Technical Context
The MAX791CPE+ integrates a precision 4.65V reset comparator with 15mV hysteresis, a separate low-line comparator set 150mV above reset threshold, and an uncommitted 1.25V power-fail comparator (PFI/PFO). Its watchdog timer uses an internal current source charging an external capacitor at SWT to generate timeout periods from 10ms to 210ms (4.7–100nF).
It features bidirectional power-path control: VOUT connects to VCC when VCC > VBATT and VCC > reset threshold; switches to VBATT when VCC falls below both conditions. The BATT ON output signals switchover, while CE IN/CE OUT provide active-low gated chip-enable with 75Ω series resistance and 6ns propagation delay under 50Ω/50pF test conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V (typ), guaranteed valid down to VCC = 1V - ensures deterministic µP reset during brownout even without battery. |
| Watchdog Timeout | 1.6s nominal (preset via SWT-to-VOUT); adjustable 10–210ms via 4.7–100nF capacitor - enables software fault detection with advance pulse warning. |
| VCC-to-VOUT On-Resistance | 1.2Ω (typ at VCC = 3V) - supports 250mA continuous output with <1mV/mA droop for stable RAM/RTC supply. |
| VBATT-to-VOUT On-Resistance | 17Ω (typ at VBATT = 2.0V) - enables 25mA battery-backup mode with minimal voltage drop for CMOS RAM retention. |
| Chip-Enable Propagation Delay | 6ns (measured at 50% points, 50Ω source, 50pF load) - preserves high-speed memory access timing during power transitions. |
| Supply Current (Normal Mode) | 50µA (typ) - extends battery life in portable equipment without compromising supervision accuracy. |
| Power-Fail Input Threshold | 1.25V (typ), ±25nA leakage - allows monitoring of non-5V rails (e.g., 3.3V, -5V via divider) with negligible loading. |
Pinout & Package
MAX791CPE+ is supplied in a 16-pin plastic DIP package (0°C to +70°C operating range), with through-hole mounting and industry-standard 0.3" width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Connects to external battery/capacitor; enables switchover when VCC falls below reset threshold and VBATT. |
| 2 VOUT | Output supply voltage | Switched output tied to VCC or VBATT; powers RAM/RTC; requires 0.1µF bypass to GND. |
| 3 VCC | +5V main supply input | Primary power rail; monitored for reset, low-line, and watchdog enable/disable logic. |
| 4 GND | Ground reference | 0V reference for all analog comparators and digital outputs; must be low-impedance. |
| 5 BATT ON | Battery-on status output | Active-high signal indicating VOUT is sourced from VBATT; drives PNP base for >250mA loads. |
| 6 PFO | Power-fail output | Open-drain output asserting low when PFI < 1.25V; sinks 3.2mA at 0.1V for NMI generation. |
| 7 PFI | Power-fail input | Non-inverting comparator input; monitors auxiliary supplies; connect to GND if unused. |
| 8 SWT | Set watchdog timeout | Capacitor connection point for adjustable timeout; internal ±100nA current source sets period. |
| 9 MR | Manual-reset input | 1.25V-threshold input; 15µs min pulse resets watchdog and initiates 200ms reset timeout. |
| 10 LOWLINE | Low-line comparator output | Asserts low when VCC drops to 4.80V (4.65V + 150mV); generates NMI on unregulated supply failure. |
| 11 WDI | Watchdog input | Three-level input (high/mid/low); transition resets timer; floating disables watchdog (biased to 1.6V). |
| 12 CE OUT | Chip-enable output | Gated CE signal; goes high-impedance during reset to prevent memory corruption; 75Ω series impedance. |
| 13 CE IN | Chip-enable input | Accepts system CE signal; high-impedance during reset; 75Ω series path to CE OUT in enabled mode. |
| 14 WDO | Watchdog output | Active-low fault indicator; asserts 70ns after WDPO pulse; remains low until next WDI transition. |
| 15 RESET | Reset output | Active-low open-drain reset; sinks 3.2mA at 0.1V; guaranteed valid to VCC = 1V with 10kΩ pull-down. |
| 16 WDPO | Watchdog-pulse output | Pulses low for ≥1ms before WDO assertion; clocks external flip-flop for two-fault shutdown latching. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET validity to VCC = 1V | Enables robust reset assertion in deep brownout scenarios without battery dependency - critical for fail-safe embedded controllers. |
| Dual-stage power-fail detection | Combines 1.25V PFI comparator (for early warning) and 4.80V LOWLINE output (for NMI-triggered response) - supports layered power-integrity monitoring. |
| Adjustable watchdog timeout (10–210ms) | Allows precise alignment with software execution windows using only a single external capacitor - eliminates need for external timing ICs. |
| On-board CE gating with 6ns delay | Prevents memory write corruption during power transitions by disabling CE path within 6ns of reset assertion - meets fast µP timing requirements. |
| MaxCap®/SuperCap® compatibility | Supports direct connection to large-value backup capacitors (e.g., 0.47F) without external charge-control circuitry - simplifies battery-free backup design. |
| 250mA VCC-mode / 25mA battery-backup output | Delivers sufficient current for real-time clocks, SRAM, and low-power logic in both primary and backup modes - eliminates need for external regulators. |
Applications
| Portable Data Logger | Industrial PLC Controller |
|---|---|
Use Scenario: Battery-powered environmental sensor node logging temperature/humidity every 10 seconds, retaining data in CMOS RAM during mains loss. IC Role / Device Role / Timing Role: Supervisory IC providing VCC monitoring, battery switchover, and watchdog supervision to ensure clean restart and data integrity. Use Value: 50µA quiescent current extends battery life; 25mA battery-backup output sustains RAM for >72 hours; 200ms reset timeout prevents spurious boot. |
Use Scenario: DIN-rail mounted programmable logic controller with nonvolatile memory, requiring immunity to factory power sags and brownouts. IC Role / Device Role / Timing Role: Power supervisor generating hardware reset, low-line NMI, and CE gating to protect I/O register writes during voltage transients. Use Value: 4.65V reset threshold with 15mV hysteresis rejects noise-induced resets; LOWLINE output triggers firmware-initiated safe shutdown before VCC collapse. |
| Medical Infusion Pump | Point-of-Sale Terminal |
Use Scenario: Life-critical infusion device with real-time clock and EEPROM storing dosage history, needing fail-safe power monitoring per IEC 62304. IC Role / Device Role / Timing Role: Dual-redundant supervision element asserting RESET and pulsing WDPO to latch safety state on software hang. Use Value: WDPO's 1ms pulse precedes WDO by 70ns, enabling external D-flip-flop to detect two consecutive faults - satisfies Class C software safety requirements. |
Use Scenario: Retail terminal with flash memory and secure element, subject to frequent AC cycling and USB power interruptions. IC Role / Device Role / Timing Role: Supervisor managing VCC/VBATT switchover, write-protection of EEPROM during power loss, and CE gating during reset. Use Value: CE IN-to-CE OUT 6ns delay preserves memory timing margins; PFI input monitors 3.3V I/O rail independently to prevent corrupted transaction commits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACPE+ | No watchdog timer; fixed 200ms reset timeout; no CE gating; 100µA supply current. | Suitable only for basic reset-only applications without software supervision or memory protection needs. | Select MAX691ACPE+ only if watchdog and CE gating are unnecessary and lower cost is prioritized over feature completeness. |
| TPS3823MPWPT | Single 3.08V reset threshold; no battery switchover; no PFI/PFO; 16-pin TSSOP only; 12µA supply current. | Designed for fixed-voltage systems without backup power; lacks low-line comparator and dual-supply capability. | Choose TPS3823MPWPT for cost-sensitive 3.3V-only designs where battery backup and multi-rail monitoring are irrelevant. |
Compared with MAX691ACPE+ and TPS3823MPWPT, the MAX791CPE+ uniquely combines adjustable watchdog, battery switchover, CE gating, and dual-stage power-fail detection in a single 16-pin DIP - making it the only option for portable µP systems requiring coordinated power integrity, memory protection, and software fault recovery.
Availability
MAX791CPE+ is available at Aetrix Electronics and suitable for portable/battery-powered equipment, industrial PLC controllers, medical infusion pumps, and point-of-sale terminals requiring stable component supply across extended production lifecycles.
Supply support for MAX791CPE+ 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 computing applications.
The MAX791 belongs to Maxim's microprocessor supervisory product line, designed specifically to consolidate power monitoring, reset generation, battery backup control, and watchdog supervision into a single IC for space-constrained embedded systems.
FAQ
What is the guaranteed minimum reset timeout duration for MAX791CPE+?
The MAX791CPE+ guarantees a minimum reset timeout of 140ms and a typical value of 200ms after VCC rises above the 4.65V threshold or after the manual reset input (MR) returns high. This timing is internally generated and independent of external components, ensuring consistent µP initialization across temperature and supply variations. The MAX791CPE+ datasheet specifies this parameter under all operating conditions from 0°C to +70°C.
Can MAX791CPE+ monitor a 3.3V supply instead of +5V?
Yes, the MAX791CPE+ can monitor a 3.3V supply using its dedicated PFI input, which has a fixed 1.25V threshold and ±25nA leakage. By connecting PFI to a resistor divider from the 3.3V rail, the comparator asserts PFO when the divided voltage falls below 1.25V - enabling accurate power-fail detection without modifying the primary VCC connection. The MAX791CPE+ does not require VCC to be 5V for PFI operation.
How does MAX791CPE+ handle the transition between VCC and VBATT power sources?
The MAX791CPE+ automatically switches VOUT from VCC to VBATT when both conditions are met: VCC falls below the 4.65V reset threshold and VCC drops below VBATT. During switchover, BATT ON asserts high, and internal PMOS switches engage with 17Ω typical on-resistance. The MAX791CPE+ maintains RESET assertion throughout the transition and guarantees VOUT stability to support CMOS RAM retention without interruption.
Is MAX791CPE+ compatible with supercapacitors for battery backup?
Yes, the MAX791CPE+ is explicitly designed for MaxCap® and SuperCap® compatibility, supporting direct connection of large-value backup capacitors (e.g., 0.47F) to VBATT. Its low 1µA standby current in battery-backup mode and controlled switchover thresholds minimize self-discharge and ensure reliable long-term RAM retention - a key feature confirmed in the MAX791CPE+ datasheet and application notes.
What happens to CE IN and CE OUT during reset assertion in MAX791CPE+?
During reset assertion, CE IN enters high-impedance state within 15µs, and CE OUT is actively pulled to VOUT (not tri-stated), preventing spurious memory writes. The transmission gate disconnects, and the 75Ω series path is disabled. This behavior is guaranteed across the full 0°C to +70°C range and is integral to the MAX791CPE+'s memory write-cycle completion function - verified in timing diagrams and electrical characteristics tables.
MAX791CPE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
MAX791CPE+ FAQ
1.How can I place an order for MAX791CPE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX791CPE+ 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 MAX791CPE+ reliable?
The price and inventory of MAX791CPE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX791CPE+ is usually 5 days.
3.What payment methods are accepted for MAX791CPE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX791CPE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX791CPE+?
MAX791CPE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX791CPE+ 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 MAX791CPE+?
For technical support, including MAX791CPE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX791CPE+ requirements.
6.How does Aetrix verify that MAX791CPE+ is sourced from the original manufacturer or authorized distributors?
All MAX791CPE+ 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 MAX791CPE+ meets industry standards.
7.What is the process for return or replacement of MAX791CPE+?
All MAX791CPE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX791CPE+, 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 MAX791CPE+ part is unused and in its original packaging.
Return procedure for MAX791CPE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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