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Analog Devices Inc./Maxim Integrated MAX704RESA+
- Part No.:
- MAX704RESA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX704RESA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,040
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Product details
Overview
MAX704RESA+ from Maxim Integrated is a 3.0V/3.3V microprocessor supervisory circuit with active-low RESET output, manual reset input (MR), watchdog timer (1.6s timeout), precision reset threshold of 2.625V (±75mV), and battery-backup switchover capability. It monitors VCC supply integrity, asserts reset during brownout or watchdog timeout, and switches VOUT to VBATT when VCC falls below 2.40V - enabling reliable CMOS RAM retention in portable controllers and embedded systems.
For engineers reviewing the MAX704RESA+ datasheet, MAX704RESA+ pinout, MAX704RESA+ application, or MAX704RESA+ equivalent, this page delivers verified functional specifications, validated SO-8 pin mapping, confirmed battery-switching behavior, and real-world design implications for power-fail warning, manual reset timing, and temperature-stable reset assertion down to VCC = 1V.
Technical Context
The MAX704RESA+ integrates a precision voltage comparator with 2.625V reset threshold (VCC rising/falling hysteresis ±10mV), a 1.6-second watchdog timer cleared by WDI edges, and a bidirectional battery switchover circuit that connects VOUT to VBATT when VCC drops below 2.40V (VSW) and VBATT > VCC. Its internal PMOS switch provides 3Ω on-resistance from VCC to VOUT and 140Ω from VBATT to VOUT.
It features a dedicated PFI input referenced to 1.237V ±20mV, enabling external power-supply monitoring; an open-drain PFO output asserted low during power-fail or VCC < VSW; and MR input with 70µA internal pull-up, supporting TTL/CMOS logic or momentary switch activation. RESET remains low for 200ms after VCC recovery or MR release.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 2.625V nominal (VCC falling), ±75mV tolerance - ensures reset assertion before VCC drops below 2.55V, critical for 3.0V ±10% systems. |
| Reset Timeout Period | 200ms typical (140–280ms over temp) - guarantees µP initialization window sufficient for oscillator stabilization and firmware boot. |
| VCC Supply Current | 40–50µA at VCC < 3.6V - enables ultra-low-power operation in battery-backed portable equipment. |
| Battery Supply Current | 0.4–1µA (C/E grade) - minimizes lithium cell drain during long-term backup mode. |
| Watchdog Timeout | 1.6s nominal (1.12–2.24s over temp) - detects µP lockup without requiring software intervention or external timing components. |
| VBATT-to-VOUT On-Resistance | 140Ω typical - limits voltage drop under 250µA load, preserving >2.0V for CMOS RAM data retention. |
| Power-Fail Input Threshold | 1.237V ±20mV - supports accurate undervoltage detection of auxiliary rails via resistor divider. |
Pinout & Package
MAX704RESA+ is housed in an 8-pin SOIC package (SO-8, 150mil width) with RoHS-compliant lead-free finish (+ suffix). Pin spacing is 1.27mm, body dimensions 4.9 × 6.0 × 1.75mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM | Switches between VCC (via 3Ω PMOS) and VBATT (via 140Ω switch); must be decoupled with 0.1µF capacitor. |
| 2 - VCC | Main system supply input | Operates from 2.72V to 5.5V; powers internal circuitry and drives VOUT when above reset threshold. |
| 3 - GND | Ground reference | Common return for VCC, VBATT, and all logic signals; requires low-inductance connection to PCB ground plane. |
| 4 - PFI | Power-fail input | Compares against 1.237V reference; asserts PFO low when input falls below threshold - used for auxiliary rail monitoring. |
| 5 - PFO | Power-fail open-drain output | Active-low signal indicating PFI < VPFT or VCC < VSW; can drive MR on MAX704/806 to trigger reset. |
| 6 - WDI | Watchdog input | Edge-sensitive (rising/falling); clears 1.6s timer on transition; tied high/low causes periodic reset. |
| 7 - RESET | Active-low reset output | Push-pull, guaranteed low for VCC < 2.625V; holds low 200ms after VCC rise/MR release - directly interfaces µP reset pin. |
| 8 - VBATT | Backup battery input | Accepts up to 6.0V; may exceed VCC; connects to VOUT during brownout - enables lithium coin-cell or supercap backup. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1V | Ensures fail-safe reset even during deep brownout, preventing µP execution from corrupted memory or unstable supply. |
| Battery-backup switchover at VSW = 2.40V | Triggers before VOUT drops below 2.0V, preserving CMOS RAM data integrity without external control logic. |
| 200ms reset timeout with restart-on-brownout | Provides deterministic boot window while automatically reasserting reset if VCC dips again - eliminates race conditions. |
| 40µA VCC supply current (typ) | Reduces standby power in always-on embedded controllers, extending battery life in portable instrumentation. |
| 1.237V ±20mV PFI reference | Enables precise monitoring of secondary supplies (e.g., 5V, 12V rails) using standard resistor dividers without calibration. |
Applications
| Battery-Powered Portable Equipment | Embedded Controller Power Monitoring |
|---|---|
|
Use Scenario: Handheld medical meters and industrial data loggers operating from single-cell lithium batteries with intermittent charging. IC Role / Device Role / Timing Role: Supervises main 3.0V rail, triggers reset on battery sag, and switches RAM to backup during charge interruption. Use Value: Prevents data corruption during battery transitions; 0.4–1µA VBATT current extends shelf life beyond 10 years. |
Use Scenario: Programmable logic controllers (PLCs) deployed in factory automation with dual 3.3V/5V supplies and watchdog-critical firmware. IC Role / Device Role / Timing Role: Monitors 3.3V µP supply, asserts RESET on brownout, and uses WDI to detect firmware hangs. Use Value: Eliminates need for discrete reset IC + watchdog timer; 1.6s timeout matches typical µP instruction loop durations. |
| Intelligent Instrumentation | Critical µP Power Monitoring |
|
Use Scenario: Benchtop oscilloscopes and spectrum analyzers requiring nonvolatile RAM retention during AC power loss. IC Role / Device Role / Timing Role: Provides VCC supervision, battery switchover, and PFI-based AC-DC converter monitoring. Use Value: 2.625V reset threshold aligns with 3.0V ±10% spec; PFO-to-MR linkage enables cascaded fault response. |
Use Scenario: Aerospace telemetry modules where supply stability must be verified before command execution. IC Role / Device Role / Timing Role: Guarantees RESET remains asserted until VCC exceeds 2.635V (rising threshold) and holds for 200ms. Use Value: 10mV hysteresis prevents oscillation near threshold; valid reset assertion down to VCC = 1V covers worst-case transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704CESA+ | Higher reset threshold (3.075V), same SO-8 package and pinout | Designed for 3.3V ±5% systems; less tolerant of brownout in 3.0V rails | Select when main supply is regulated 3.3V with tight tolerance and no deep undervoltage events. |
| MAX706RESA+ | No watchdog timer or battery switchover; only RESET/PFI/PFO functions | Lacks WDI and VBATT support; lower quiescent current (25µA) | Choose for cost-sensitive, non-battery-backed applications where watchdog independence is not required. |
Compared with MAX704CESA+, the MAX704RESA+ offers tighter brownout immunity for 3.0V systems but sacrifices compatibility with 3.3V nominal rails; versus MAX706RESA+, it adds critical watchdog and battery backup functionality at the cost of higher complexity and current draw.
Availability
MAX704RESA+ is available at Aetrix Electronics and suitable for battery-powered computers and controllers, embedded controllers, and intelligent instrumentation requiring stable component supply across industrial temperature ranges (-40°C to +85°C).
Supply support for MAX704RESA+ 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 communications markets.
The MAX704 series belongs to Maxim's microprocessor supervisory product line, engineered specifically for robust power-monitoring and fail-safe reset generation in 3.0V/3.3V embedded systems with battery backup requirements.
FAQ
What is the exact reset threshold voltage for MAX704RESA+ and how does it behave during power-up?
The MAX704RESA+ has a nominal reset threshold of 2.625V, with guaranteed minimum of 2.55V and maximum of 2.70V during VCC falling. During power-up, reset is deasserted when VCC rises above 2.635V (rising threshold), then held low for 200ms by the internal timer. This ensures µP reset remains active long enough for clock stabilization and firmware initialization before release.
Can MAX704RESA+ operate without a backup battery, and what modifications are required?
Yes, MAX704RESA+ can operate without a backup battery: connect both VBATT and VOUT pins directly to VCC. This disables battery switchover and configures VOUT as a direct VCC output. Note that PFI and PFO remain functional for auxiliary supply monitoring, and all other supervisory features - including RESET, WDI, and MR - operate unchanged.
How does the watchdog timer in MAX704RESA+ respond to WDI signal transitions?
The MAX704RESA+ watchdog timer resets on any edge (rising or falling) at the WDI pin and begins counting anew. If no edge occurs within 1.6 seconds, RESET is asserted. While RESET is active, the timer is held cleared and does not count. The timer resumes only after RESET deasserts - ensuring reliable detection of µP lockup without false triggers from noise or idle states.
What is the maximum allowable voltage on VBATT relative to VCC in MAX704RESA+?
VBATT may safely exceed VCC in MAX704RESA+ - the device explicitly supports lithium coin cells (e.g., 3.6V) powering RAM while VCC is at 3.0V or 3.3V. Absolute maximum rating is +6.0V on VBATT, and the internal switchover circuit isolates VCC and VBATT paths, preventing backfeed. No external diode is required.
Does MAX704RESA+ provide hysteresis on its reset comparator, and why is it important?
Yes, MAX704RESA+ includes ~10mV typical hysteresis between rising (2.635V) and falling (2.625V) reset thresholds. This prevents oscillatory reset assertion near the trip point during slow-rising or noisy VCC conditions - a critical feature for stable boot in systems with unregulated supplies or long PCB traces.
MAX704RESA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-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:
- 2.625V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX704RESA+ FAQ
1.How can I place an order for MAX704RESA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX704RESA+ 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 MAX704RESA+ reliable?
The price and inventory of MAX704RESA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX704RESA+ is usually 5 days.
3.What payment methods are accepted for MAX704RESA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX704RESA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX704RESA+?
MAX704RESA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX704RESA+ 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 MAX704RESA+?
For technical support, including MAX704RESA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX704RESA+ requirements.
6.How does Aetrix verify that MAX704RESA+ is sourced from the original manufacturer or authorized distributors?
All MAX704RESA+ 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 MAX704RESA+ meets industry standards.
7.What is the process for return or replacement of MAX704RESA+?
All MAX704RESA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX704RESA+, 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 MAX704RESA+ part is unused and in its original packaging.
Return procedure for MAX704RESA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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