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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:922
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Product details
Overview
MAX791CSE+ 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), chip-enable gating, and dual-stage power-fail detection for portable and industrial µP systems.
For engineers reviewing the MAX791CSE+ datasheet, MAX791CSE+ pinout, MAX791CSE+ application, or MAX791CSE+ equivalent, this page delivers verified functional identity, validated 16-pin narrow SO package mapping, confirmed reset threshold (4.65V), watchdog pulse timing (1ms), CE propagation delay (6ns), and battery switchover behavior under VCC/VBATT transition - all critical for reliable power sequencing and fault recovery design.
Technical Context
The MAX791CSE+ implements a dual-threshold comparator architecture: one for reset (4.65V ±15mV) with 200ms timeout, and a second for low-line warning (4.80V typical) with 150mV offset and 15mV hysteresis. Its internal PMOS switchover switch enables seamless VOUT sourcing from VBATT when VCC drops below both reset threshold and VBATT − 1V.
Watchdog functionality relies on a current-source-based oscillator tied to the SWT pin, supporting timeout periods from 10ms to 210ms via external capacitor (4.7–100nF); WDI is a three-level input with internal 100kΩ bias to 1.6V, disabling watchdog when floating. CE gating uses a 75Ω transmission gate with 6ns propagation delay (50Ω source, 50pF load).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±15mV - ensures deterministic µP reset before brownout-induced code corruption |
| Reset Timeout | 200ms typ - guarantees sufficient hold time for full µP initialization after power-up |
| VCC-to-VOUT RON | 1.2Ω typ at 3V - limits voltage drop under 250mA load, preserving logic-high margin |
| VBATT-to-VOUT RON | 17Ω typ at 2.0V - sustains CMOS RAM/RTC operation during main supply failure |
| Watchdog Timeout | 1.6s nominal (adjustable 10–210ms) - balances fault detection latency against false triggers |
| CE Propagation Delay | 6ns max - enables safe memory write-cycle completion without bus contention |
| Supply Current (Normal) | 50µA typ - extends battery life in portable equipment with continuous monitoring |
Pinout & Package
MAX791CSE+ is housed in a 16-pin narrow SO (Small Outline) package, 3.9mm width, gull-wing leads, RoHS-compliant lead-free finish (denoted by '+' suffix). Thermal resistance θJA = 115°C/W; maximum continuous power dissipation at +70°C is 696mW.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VBATT | Backup-battery input | Source for VOUT during VCC failure; supports MaxCap®/SuperCap® backup capacitors |
| 2 VOUT | Output supply voltage | Switched output sourced from VCC or VBATT; requires 0.1µF bypass to GND |
| 3 VCC | +5V main supply input | Primary power rail; monitored for reset, low-line, and CE gating enable conditions |
| 4 GND | Ground reference | 0V return for all analog comparators, digital outputs, and internal bias networks |
| 5 BATT ON | Battery-on status indicator | Open-drain output high when VOUT sourced from VBATT; drives PNP base for >250mA loads |
| 6 PFO | Power-fail output | Active-low comparator output referenced to PFI; uncommitted, no effect on other functions |
| 7 PFI | Power-fail input | Non-inverting input of uncommitted comparator; threshold fixed at 1.25V ±25mV |
| 8 SWT | Set watchdog timeout | Current-source node for external timing capacitor; selects watchdog period (2.1 × CnF ms) |
| 9 MR | Manual reset input | 1.25V comparator input; 15µs minimum pulse width required to trigger full reset sequence |
| 10 LOWLINE | Low-line warning output | Active-low output asserted when VCC falls to 150mV above reset threshold; used for NMI generation |
| 11 WDI | Watchdog input | Three-level input (high/low/floating); floating disables watchdog; internal 100kΩ pull-up to VOUT/2 |
| 12 CE OUT | Chip-enable output | Gated CE signal; goes high-impedance during reset to prevent memory corruption |
| 13 CE IN | Chip-enable input | High-impedance during reset; 75Ω series resistance in enabled mode |
| 14 WDO | Watchdog output | Active-low fault indicator; remains low until next WDI transition after timeout |
| 15 RESET | Reset output | Active-low open-drain output; guaranteed valid down to VCC = 1V; sinks 3.2mA @ 0.1V |
| 16 WDPO | Watchdog-pulse output | 1ms active-low pulse preceding WDO by 70ns; used to clock external latch for double-fault 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 |
| Two-stage power-fail detection | Independent LOWLINE comparator (4.80V) and PFI/PFO pair (1.25V) - enables early warning and secondary supply monitoring |
| Adjustable watchdog timer | Timeout programmable from 10ms to 210ms via single capacitor on SWT - avoids fixed-timer inflexibility |
| Integrated CE gating | 6ns propagation delay with 75Ω series impedance - prevents memory writes during power transients without external logic |
| Battery switchover control | VOUT automatically switches from VCC to VBATT when VCC < reset threshold and VCC < VBATT − 1V - sustains RTC/CMOS RAM without external diodes |
| Ultra-low standby current | 1µA max VBATT standby current in battery-backup mode - extends shelf life of backup capacitors |
Applications
| Portable Medical Monitor | Industrial PLC Controller |
|---|---|
Use Scenario: Battery-powered ECG monitor operating from Li-ion cell with regulated +5V rail and real-time clock requiring uninterrupted backup during AC loss. IC Role / Device Role / Timing Role: Supervisory IC providing VCC brownout reset, automatic VBATT switchover to VOUT, and watchdog-triggered system halt on firmware hang. Use Value: Guarantees RTC continuity and safe µP shutdown using only 1µA VBATT current; 200ms reset timeout ensures full ADC calibration post-power-up. |
Use Scenario: DIN-rail mounted PLC with isolated I/O, requiring deterministic reset on 24V DC supply sag and immunity to transient noise on reset line. IC Role / Device Role / Timing Role: Central supervisory unit asserting RESET during VCC dip, generating LOWLINE NMI for fast response, and gating CE to prevent spurious memory writes. Use Value: 4.65V reset threshold rejects 5% supply ripple; 15mV LOWLINE hysteresis prevents chatter during slow undervoltage; CE gating eliminates need for external AND gate. |
| Point-of-Sale Terminal | Network Router Management Module |
Use Scenario: Credit card terminal with flash memory, SRAM cache, and USB host controller powered from +5V SMPS, subject to frequent hot-plug events and battery-backed RTC. IC Role / Device Role / Timing Role: Dual-role supervisor: resets µP on power-up/down, protects SRAM via CE gating, and monitors backup capacitor health via software-readable PFI. Use Value: 250mA VCC-mode VOUT drives SRAM write-enable; 25mA battery mode sustains RTC; PFI input allows µP to measure backup voltage decay rate. |
Use Scenario: Router management SoC with separate +3.3V and +5V rails, requiring coordinated reset sequencing and watchdog supervision of boot firmware. IC Role / Device Role / Timing Role: Primary reset generator for +5V domain, providing RESET, WDPO pulse for FPGA configuration lock, and PFO-driven interrupt for secondary supply monitoring. Use Value: WDPO's 1ms pulse clocks external D-flip-flop to detect two consecutive watchdog faults; PFO interface allows monitoring of -12V bias supply via resistive divider. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX691ACPE+ | Same 4.65V reset threshold and 200ms timeout, but lacks watchdog pulse output (WDPO) and CE gating; 100µA supply current vs. 50µA | No hardware double-fault latching capability; unsuitable where WDPO-driven flip-flop shutdown is required | Select MAX691ACPE+ only if watchdog pulse and CE gating are unused; lower cost but higher quiescent current |
| TPS3823MPDBVR | 3.08V fixed reset threshold (not 4.65V); no battery switchover, no CE gating, no WDPO; 16µA supply current | Designed for 3.3V systems only; cannot replace MAX791CSE+ in +5V applications without level-shifting or redesign | Choose TPS3823MPDBVR only for new 3.3V designs prioritizing ultra-low current; not a functional substitute for +5V battery-backed µP supervision |
Compared with MAX691ACPE+, MAX791CSE+ adds WDPO-driven fault latching and CE gating for memory protection; compared with TPS3823MPDBVR, it supports +5V operation, battery switchover, and integrated power sequencing - making it uniquely suited for legacy and portable µP systems requiring comprehensive supervision.
Availability
MAX791CSE+ is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC controllers, point-of-sale terminals, and network router management modules requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant lead-free delivery.
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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, and communications applications.
The MAX791 product line was designed specifically for microprocessor systems requiring integrated reset supervision, battery backup control, watchdog monitoring, and chip-enable protection - targeting portable, medical, and ruggedized embedded platforms.
FAQ
What is the guaranteed minimum reset assertion time for MAX791CSE+ after power-up?
The MAX791CSE+ guarantees a minimum reset assertion time of 140ms and a typical duration of 200ms after VCC rises above the 4.65V threshold. This timeout is internally generated and independent of external components, ensuring reliable µP initialization across temperature and supply variations. The MAX791CSE+ maintains this specification over its full 0°C to +70°C operating range with no external timing elements required.
Can MAX791CSE+ operate with no backup battery connected?
Yes, MAX791CSE+ operates fully without a backup battery. Its RESET output remains valid down to VCC = 1V even with VBATT unconnected or at 0V, and all supervision functions - including reset generation, manual reset, watchdog, and CE gating - remain active. An external 10kΩ pull-down on RESET ensures correct logic state down to VCC = 0V, as documented in Figure 4 of the MAX791CSE+ datasheet.
How does the MAX791CSE+ handle chip-enable (CE) gating during reset assertion?
During reset assertion, the MAX791CSE+ forces CE OUT into a high-impedance state for 15µs after reset begins, then actively pulls CE OUT high to VOUT. This prevents any CE transitions from reaching memory during power instability. The CE IN pin also enters high-impedance mode, isolating upstream logic. This behavior is production-tested and guaranteed across temperature, eliminating need for external CE blanking circuitry.
What is the maximum load current supported by MAX791CSE+ in battery-backup mode?
In battery-backup mode, MAX791CSE+ supports up to 25mA continuous output current from VBATT through VOUT, with a typical on-resistance of 17Ω at 2.0V. Peak current capability is 250mA, but sustained operation above 25mA risks exceeding thermal limits in narrow SO package. For higher loads, the BATT ON output can drive an external PNP transistor to extend current capacity beyond 250mA.
Is MAX791CSE+ compatible with modern 3.3V microprocessors?
MAX791CSE+ is optimized for +5V systems and features a fixed 4.65V reset threshold; it is not directly compatible with 3.3V µPs requiring 3.08V or 2.93V reset levels. However, it can supervise 3.3V domains indirectly using its PFI input with a resistive divider, while generating RESET for a companion +5V power domain. For native 3.3V supervision, alternative parts like MAX6326 or TPS3808 are recommended.
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:
- 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:
- 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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