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Analog Devices Inc./Maxim Integrated MAX794CPE+
- Part No.:
- MAX794CPE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX794CPE+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,390
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Product details
Overview
The MAX794CPE+ from Maxim Integrated is a 3.0V/3.3V adjustable microprocessor supervisory circuit that provides backup-battery switchover, externally programmable reset threshold (via resistor divider on RESET IN), independent watchdog timer (1.6s timeout), and chip-enable signal gating with ≤7ns propagation delay. It operates across 0°C to +70°C and supports battery voltages exceeding VCC (e.g., 3.6V Li) in portable computing and embedded controllers requiring reliable power monitoring.
For engineers reviewing the MAX794CPE+ datasheet, MAX794CPE+ pinout, MAX794CPE+ application, or MAX794CPE+ equivalent, key selection criteria include its adjustable reset threshold (1.212V–1.287V input reference), guaranteed reset assertion down to VCC = 1V, battery-freshness seal capability, and dual active-high/active-low reset outputs for robust µP interface.
Technical Context
The MAX794CPE+ implements an external resistor-divider–based reset threshold comparator referenced to a precision 1.240V internal bandgap (±28mV tolerance), enabling user-defined trip points between VSW (battery switch threshold) and 5.5V. Its watchdog circuit monitors WDI transitions and asserts WDO low after 1.6s of inactivity, with automatic recovery on next WDI edge.
Chip-enable gating uses a series transmission gate between CE IN and CE OUT, disabling during reset assertion to prevent RAM corruption; it features 46Ω on-resistance and ≤7ns propagation delay under typical load. The BATT ON output drives external PMOS/NPN switches for high-current battery switchover beyond 75mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold Input | 1.212V–1.287V (adjustable via external divider; sets VRST = VRST_IN × (R1/R2 + 1)) |
| Watchdog Timeout | 1.6s ±15% (guaranteed detection window for µP hang; resets on WDI transition) |
| VCC Supply Current | 46µA typ (at VCC = 3.3V, TA = +25°C; enables ultra-low-power battery-backup operation) |
| Battery Switch Threshold | 2.55V–2.80V (VSW range where OUT transitions from VCC to BATT as VCC falls) |
| CE IN-to-CE OUT Delay | ≤7ns max (ensures compatibility with high-speed µPs without timing violation) |
| Operating Temperature | 0°C to +70°C (commercial-grade rating suitable for industrial embedded and portable equipment) |
| Package | 16-pin plastic DIP (0.3-inch width; through-hole mounting for prototyping and legacy designs) |
Pinout & Package
MAX794CPE+ is housed in a 16-pin plastic DIP (dual in-line package) with 0.3-inch body width and standard 0.1-inch pin pitch, compatible with through-hole PCB assembly and socket-based evaluation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT (Pin 1) | Supply output for CMOS RAM | Switches between VCC and BATT based on voltage thresholds; powers RAM during main supply failure |
| RESET IN (Pin 3) | Adjustable reset threshold input | Accepts external resistor divider to set precise reset point; referenced to 1.240V internal bandgap |
| VCC (Pin 2) | Main supply input | Primary 3.0V/3.3V system rail; powers internal circuitry and defines reset comparator reference |
| PFO (Pin 7) | Power-fail comparator output | Active-low open-drain signal indicating VCC < VSW or PFI < VPFT; used to enable battery freshness seal |
| RESET (Pin 15) | Active-low reset output | Open-drain output requiring external pullup; asserts low for ≥200ms during undervoltage or MR event |
| CE OUT (Pin 12) | Chip-enable output | Gated version of CE IN; disabled during reset to prevent erroneous RAM writes |
| GND (Pin 6) | Ground reference | Common return path for all analog and digital functions; critical for accurate threshold sensing |
| PFI (Pin 4) | Power-fail comparator input | Monitors auxiliary supply or voltage divider; triggers PFO low when below 1.212V–1.287V threshold |
| CE IN (Pin 11) | Chip-enable input | Directly drives CE OUT when not in reset; high-impedance during reset assertion |
| WDI (Pin 10) | Watchdog input | Edge-sensitive input; 100ns minimum pulse width detectable; clears 1.6s watchdog timer on transition |
| MR (Pin 8) | Manual reset input | Active-low with 70µA internal pullup; asserts reset for 200ms after rising edge |
| WDO (Pin 9) | Watchdog output | Active-low open-drain output signaling watchdog timeout; can be wired to MR for auto-reset |
| LOWLINE (Pin 14) | Early power-fail warning | Active-low output asserting when VCC falls to VLR (VRST − 10mV to −60mV); enables NMI for graceful shutdown |
| BATT (Pin 16) | Backup-battery input | Accepts up to 6V battery (e.g., 3.6V Li); enables seamless switchover even when VBATT > VCC |
| BATT ON (Pin 5) | Battery-on driver output | Active-high logic-level signal driving external PMOS/NPN switch for high-current battery path |
| RESET (Pin 13) | Active-high reset output | Push-pull output sourcing/sinking current; inverse of RESET; directly interfaces µP reset pin |
Key Features
| Feature | Design Value |
|---|---|
| Externally adjustable reset threshold | Enables precise match to custom supply tolerances (e.g., 3.0V ±10%) without device change |
| Guaranteed reset assertion to VCC = 1V | Ensures µP remains held in reset during deep brownout, preventing erratic execution |
| Battery freshness seal | Disables battery leakage until first power-up, preserving shelf life of sealed systems |
| On-board CE signal gating (≤7ns delay) | Prevents corrupted RAM writes during undervoltage without adding external logic or timing margin |
| Independent 1.6s watchdog timer | Provides fail-safe recovery for firmware hangs without relying on µP's internal watchdog |
| Backup-battery switchover with VBATT > VCC | Supports standard 3.6V lithium coin cells in 3.3V systems, eliminating need for level-shifting |
Applications
| Battery-Powered Computers | Embedded Controllers |
|---|---|
Use Scenario: Portable data logger with nonvolatile RAM retention during main power loss. IC Role / Device Role / Timing Role: Supervisory IC providing seamless VCC-to-BATT switchover, RAM write protection via CE gating, and low-line warning for preemptive data save. Use Value: Prevents data corruption by holding µP in reset until stable VCC returns and blocking CE during brownout. | Use Scenario: Industrial PLC module operating in environments with unstable 3.3V supply rails. IC Role / Device Role / Timing Role: Voltage monitor and watchdog enforcing deterministic reset behavior; LOWLINE triggers NMI for controlled I/O shutdown before full undervoltage. Use Value: Eliminates uncontrolled crashes by asserting reset at precisely defined VCC thresholds and detecting firmware lockups. |
| Intelligent Controllers | Critical µP Power Monitoring |
Use Scenario: Smart HVAC controller with real-time clock and configuration storage. IC Role / Device Role / Timing Role: Backup power manager enabling RTC operation and EEPROM integrity during AC dropout; BATT OK confirms battery health before switchover. Use Value: Ensures timekeeping continuity and prevents configuration loss using verified battery voltage (VBOK ≥2.0V). | Use Scenario: Medical diagnostic device requiring fail-safe power sequencing and audit-trail logging. IC Role / Device Role / Timing Role: Dual-reset supervisor (RESET and RESET) providing redundant reset signaling; manual reset (MR) supports field service recovery. Use Value: Meets safety-critical requirements with guaranteed 200ms reset pulse width and VCC = 1V assertion margin. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX793CPE+ | Fixed reset threshold (3.00V–3.15V), includes BATT OK output and uncommitted voltage monitor; no RESET IN pin | Suitable for systems with stable 3.3V supplies where adjustable threshold is unnecessary; adds battery-status feedback | Select when fixed-threshold supervision and battery health monitoring are required without external resistor network |
| TPS3808G33DBVR | Fixed 3.3V reset threshold, 200ms timeout, no watchdog or CE gating; SOT-23-6 package | Targeted at space-constrained, cost-sensitive applications needing basic reset only; lacks battery switchover and advanced features | Choose for minimal footprint and lower BOM cost where watchdog, CE gating, and battery support are not needed |
Compared with MAX793CPE+, the MAX794CPE+ trades fixed-threshold simplicity for design flexibility via external reset programming and adds manual reset input; versus TPS3808G33DBVR, it delivers comprehensive supervision (watchdog, CE gating, battery management) at the cost of larger DIP packaging and higher complexity.
Availability
MAX794CPE+ is available at Aetrix Electronics and suitable for battery-powered computers, embedded controllers, and intelligent controllers requiring stable component supply with long-term industrial availability.
Supply support for MAX794CPE+ 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, communications, and computing markets.
The MAX793/MAX794/MAX795 product line was designed specifically for 3.0V/3.3V microprocessor systems requiring integrated power supervision, battery backup management, and fault detection - targeting portable, embedded, and mission-critical applications.
FAQ
What is the function of the RESET IN pin on the MAX794CPE+?
The RESET IN pin on the MAX794CPE+ accepts an external resistor divider to set the precise reset threshold voltage. Internally referenced to a 1.240V bandgap, it allows programming VRST anywhere from the battery switch threshold (VSW) up to 5.5V. This makes the MAX794CPE+ adaptable to custom supply tolerances without changing the IC, unlike fixed-threshold variants such as the MAX793CPE+.
Does the MAX794CPE+ support battery voltages higher than VCC?
Yes, the MAX794CPE+ explicitly supports VBATT > VCC - for example, a 3.6V lithium battery in a 3.3V system. Its internal p-channel MOSFET switch ensures seamless switchover from VCC to BATT when VCC falls below VSW (2.55V–2.80V), and reconnection to VCC when VCC rises above the reset threshold. This eliminates the need for external level-shifting circuitry.
How does the watchdog feature work in the MAX794CPE+?
The MAX794CPE+ watchdog monitors the WDI pin and asserts WDO low if no edge occurs within 1.6s. WDO returns high on the next WDI transition. Unlike some supervisors, this watchdog cannot be disabled. When WDO is connected to MR, each timeout generates a 200ms reset pulse - enabling autonomous recovery from firmware hangs without µP intervention.
What is the purpose of the BATT ON output on the MAX794CPE+?
The BATT ON output on the MAX794CPE+ is an active-high logic signal that indicates when the internal switch has connected BATT to OUT. It drives the gate/base of an external PMOS or NPN transistor to handle battery currents exceeding the IC's 75mA limit. This extends the usable battery capacity in high-load applications like RAM backup with large capacitive loads.
Can the MAX794CPE+ be used without a backup battery?
Yes, the MAX794CPE+ functions fully without a backup battery. Connect BATT to VCC and OUT, and leave PFO unconnected or tied to VCC. All supervision features - reset generation, watchdog, LOWLINE warning, and CE gating - remain operational. The battery-related functions (BATT ON, BATT OK, freshness seal) are simply inactive, making the MAX794CPE+ suitable for non-battery systems requiring robust voltage monitoring.
MAX794CPE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- Adjustable/Selectable
- Output:
- Open Drain, Push-Pull
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
MAX794CPE+ FAQ
1.How can I place an order for MAX794CPE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX794CPE+ 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 MAX794CPE+ reliable?
The price and inventory of MAX794CPE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX794CPE+ is usually 5 days.
3.What payment methods are accepted for MAX794CPE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX794CPE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX794CPE+?
MAX794CPE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX794CPE+ 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 MAX794CPE+?
For technical support, including MAX794CPE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX794CPE+ requirements.
6.How does Aetrix verify that MAX794CPE+ is sourced from the original manufacturer or authorized distributors?
All MAX794CPE+ 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 MAX794CPE+ meets industry standards.
7.What is the process for return or replacement of MAX794CPE+?
All MAX794CPE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX794CPE+, 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 MAX794CPE+ part is unused and in its original packaging.
Return procedure for MAX794CPE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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