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Analog Devices Inc./Maxim Integrated MAX704EPA+
- Part No.:
- MAX704EPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX704EPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,011
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Product details
Overview
MAX704EPA+ from Maxim Integrated is a microprocessor supervisory circuit providing active-low reset, battery-backup switching, 1.25V power-fail detection, and manual reset input in an 8-pin PDIP package. It asserts reset below 4.40V VCC, delivers 200ms reset pulse width, draws 200µA supply current, and supports CMOS RAM backup during brownout. It is used in industrial controllers and intelligent instruments requiring reliable power monitoring.
For engineers reviewing the MAX704EPA+ datasheet, MAX704EPA+ pinout, MAX704EPA+ application, or MAX704EPA+ equivalent, key selection factors include its −40°C to +85°C operating range, guaranteed RESET assertion down to VCC = 1.2V, battery switchover hysteresis of 40mV, and compatibility with lithium batteries (3.0–3.6V) and supercapacitor backup sources.
Technical Context
The MAX704EPA+ integrates four core functions: a precision voltage monitor with 4.40V ±40mV threshold, a battery switchover circuit using p-channel MOSFETs (5Ω in VCC mode, 80Ω in VBATT mode), a 1.25V reference-based power-fail comparator with TTL/CMOS-compatible PFO output, and a debounced manual reset input with 250µA internal pullup.
Its reset generator guarantees valid low-state output even as VCC falls to 1.2V, and its battery-backup mode disables PFI/PFO while forcing RESET low and connecting VBATT to VOUT - all with quiescent current reduced to 5.0µA across full temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V ±40mV - ensures deterministic μP reset initiation during +5V supply brownout |
| Reset Pulse Width | 140–280ms (typ. 200ms) - provides sufficient time for μP initialization before release | Supply Current | 200–500µA (−40°C to +85°C) - enables low-power system monitoring without burdening supply |
| Battery-Backup Current | 5.0µA max (full temp range) - preserves backup battery life for years in standby |
| VOUT Output Drop | VCC − 0.25V at 50mA - maintains stable RAM supply under load during VCC failure |
| MR Input Threshold | 0.8V (low), 2.0V (high) - ensures robust TTL/CMOS switch or logic-level compatibility |
| PFI Threshold | 1.25V ±50mV - enables accurate power-fail warning or low-battery detection via external divider |
Pinout & Package
MAX704EPA+ uses an 8-pin plastic dual in-line package (PDIP) with 0.3-inch body width, through-hole mounting, and RoHS-compliant lead(Pb)-free finish (indicated by '+' suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | RAM supply output | Switches between VCC (via 5Ω p-MOSFET) and VBATT (via 80Ω p-MOSFET) based on reset threshold crossing |
| 2 - VCC | +5V main supply input | Primary power source; powers internal circuitry and enables VOUT connection when above 4.40V |
| 3 - GND | Ground reference | Common return for all analog and digital functions; substrate must remain unconnected |
| 4 - PFI | Power-fail comparator input | Monitors external voltage divider; triggers PFO low when input falls below 1.25V |
| 5 - PFO | Power-fail comparator output | Active-low open-drain output; disabled and forced low during battery-backup mode |
| 6 - MR | Manual reset input | Active-low TTL/CMOS-compatible input with 250µA internal pullup; debounced by reset timer |
| 7 - RESET | Reset output | Active-low push-pull output; asserted low during power-up, brownout, or MR activation |
| 8 - VBATT | Battery backup input | Accepts 2.8–4.55V lithium or supercap source; enables automatic RAM switchover when VCC fails |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET assertion to VCC = 1.2V | Ensures fail-safe reset hold-down even during deep brownout, preventing μP runaway |
| 40mV battery switchover hysteresis | Prevents oscillatory switching between VCC and VBATT when supply decays slowly near threshold |
| 50nA quiescent current in battery-backup mode | Extends 3.6V lithium battery life beyond 10 years in typical static RAM applications |
| 200ms minimum reset pulse width | Meets μP reset timing requirements for Intel 80Cxx, Motorola 68xxx, and compatible architectures |
| 1.25V precision reference for PFI | Enables accurate undervoltage detection of non-+5V rails (e.g., +3.3V, −5V) using external resistor networks |
Applications
| Industrial Controllers | Intelligent Instruments |
|---|---|
Use Scenario: PLCs and remote I/O modules operating in harsh environments with fluctuating 5V supplies. IC Role / Device Role / Timing Role: Supervisory circuit ensuring deterministic μP reset and RAM retention during line sags or interruptions. Use Value: Prevents firmware corruption and data loss by asserting RESET before VCC drops below 4.40V and switching RAM to VBATT within 200ms. | Use Scenario: Portable multimeters and calibration equipment requiring long-term memory retention without mains power. IC Role / Device Role / Timing Role: Battery switchover controller and power-fail warning generator for SRAM-backed configuration storage. Use Value: Enables >10-year battery life using 3.6V lithium cells while delivering 1.25V-referenced low-battery alerts via PFO. |
| Critical μP Power Monitoring | Computers |
Use Scenario: Embedded systems where unexpected reset could cause safety-critical state errors (e.g., medical devices, avionics support units). IC Role / Device Role / Timing Role: Primary reset supervisor with guaranteed operation down to VCC = 1.2V and manual reset override capability. Use Value: Eliminates need for external reset timers or discrete comparators, reducing BOM count and layout area by 30%. | Use Scenario: Legacy desktop motherboards and embedded PC/104 systems using +5V-tolerant μPs and CMOS RAM. IC Role / Device Role / Timing Role: Dual-function IC providing both reset generation and battery-backed RAM supply switching. Use Value: Replaces discrete diode-OR + reset IC solutions, cutting board space by 40% and improving switchover accuracy to ±20mV. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704CSA | Same functionality and electrical specs, but 8-pin SO package and 0°C to +70°C temperature range | Suitable for commercial-grade PCBs with surface-mount assembly; lacks extended temperature qualification | Select MAX704CSA only if ambient operating temperature stays within 0°C–70°C and SO packaging is preferred. |
| MAX706ESA | No battery backup; includes watchdog timer and CE write-protect; 4.40V reset threshold; 8-pin SO | Used where RAM backup is unnecessary but system-level watchdog supervision is required | Choose MAX706ESA when system reliability depends on periodic watchdog timeout rather than battery-backed memory retention. |
Compared with MAX704CSA, MAX704EPA+ offers extended temperature operation and through-hole mounting for ruggedized designs; compared with MAX706ESA, it prioritizes battery switchover over watchdog functionality - making it optimal for static RAM preservation in field-deployed instrumentation.
Availability
MAX704EPA+ is available at Aetrix Electronics and suitable for industrial controllers, intelligent instruments, critical μP power monitoring, and legacy computer systems requiring stable component supply across −40°C to +85°C operation.
Supply support for MAX704EPA+ 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 is a semiconductor company specializing in analog and mixed-signal ICs for power management, interface, sensing, and reliability-critical applications.
The MAX703/MAX704 product line was designed specifically for cost-sensitive microprocessor systems needing integrated reset, battery switchover, and power-fail warning - eliminating discrete solutions in industrial and instrumentation markets.
FAQ
What is the guaranteed minimum reset pulse width for MAX704EPA+?
The MAX704EPA+ guarantees a reset pulse width of at least 140ms, with a typical value of 200ms and maximum of 280ms. This timing is internally generated and independent of external components, ensuring consistent μP initialization across temperature and supply variations. The pulse begins when VCC rises above 4.40V or when MR transitions from low to high, and remains active for the full duration before releasing RESET high. This behavior is confirmed in the Electrical Characteristics table on page 2 of the MAX704 datasheet.
Can MAX704EPA+ operate with a 3.3V main supply?
No, MAX704EPA+ is specified only for +5V nominal operation (VCC = +4.5V to +5.5V). Its 4.40V reset threshold and internal circuitry require VCC ≥ 4.5V to function correctly; operation below this violates Absolute Maximum Ratings and invalidates all guaranteed specifications. For 3.3V systems, consider the MAX6326 series or MAX708, which offer 3.08V or adjustable thresholds. The MAX704EPA+ datasheet explicitly states VCC operating range and does not support 3.3V rail monitoring.
What is the maximum allowable backup battery voltage for MAX704EPA+?
The maximum allowable backup battery voltage for MAX704EPA+ is 4.55V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing internal substrate diodes (D1 in Figure 3), causing unwanted current flow from VBATT to VCC when supplies are near threshold. This can degrade reset accuracy and increase quiescent current. Lithium cells (3.0–3.6V) and properly sized supercaps (≤4.55V after charging) comply safely. The 4.55V limit is strictly enforced across the full −40°C to +85°C temperature range.
Does MAX704EPA+ support watchdog timer functionality?
No, MAX704EPA+ does not include a watchdog timer. It provides only four core functions: reset generation, battery switchover, power-fail detection (PFI/PFO), and manual reset (MR). Watchdog capability is present in other Maxim supervisory ICs like MAX706, MAX791, or MAX693A - but not in the MAX703/MAX704 family. The datasheet's Feature list, Block Diagram (Figure 1), and Table 3 ("Maxim Microprocessor Supervisory Products") confirm absence of WDI input or watchdog timeout period specification for MAX704EPA+.
How does MAX704EPA+ behave during battery replacement while VCC is active?
MAX704EPA+ allows safe battery replacement while VCC remains valid (≥4.40V). Because battery-backup mode activates only when VCC falls below the reset threshold, the device continues normal operation with VCC powering VOUT - and RESET remains deasserted. Floating VBATT during replacement causes no reset assertion, unlike older switchover ICs that trigger on VCC/VBATT proximity. This behavior is explicitly documented in the "Replacing the Backup Battery" section (page 6), confirming zero risk of unintended reset during maintenance.
MAX704EPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.4V
- Output:
- Push-Pull, Totem Pole
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
MAX704EPA+ FAQ
1.How can I place an order for MAX704EPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX704EPA+ 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 MAX704EPA+ reliable?
The price and inventory of MAX704EPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX704EPA+ is usually 5 days.
3.What payment methods are accepted for MAX704EPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX704EPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX704EPA+?
MAX704EPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX704EPA+ 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 MAX704EPA+?
For technical support, including MAX704EPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX704EPA+ requirements.
6.How does Aetrix verify that MAX704EPA+ is sourced from the original manufacturer or authorized distributors?
All MAX704EPA+ 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 MAX704EPA+ meets industry standards.
7.What is the process for return or replacement of MAX704EPA+?
All MAX704EPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX704EPA+, 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 MAX704EPA+ part is unused and in its original packaging.
Return procedure for MAX704EPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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