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Analog Devices Inc./Maxim Integrated MAX704CPA+
- Part No.:
- MAX704CPA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
MAX704CPA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,999
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Product details
Overview
MAX704CPA+ from Maxim Integrated is a microprocessor supervisory circuit providing active-low reset, battery-backup switching, 1.25V power-fail detection, and manual reset input for +5V systems. It asserts RESET below 4.40V with 200ms pulse width, supports CMOS RAM backup via VOUT, and operates from 0°C to +70°C in 8-pin PDIP packaging. Used in critical μP power monitoring where brownout resilience and low-battery switchover are required.
For engineers reviewing the MAX704CPA+ datasheet, MAX704CPA+ pinout, MAX704CPA+ application, or MAX704CPA+ equivalent, key selection criteria include reset threshold accuracy (4.40V ±150mV), battery-switch hysteresis (40mV), quiescent current (200µA active / 50nA backup mode), guaranteed RESET assertion down to VCC = 1V, and compatibility with lithium batteries (3.0–3.6V) or supercaps.
Technical Context
The MAX704CPA+ integrates four core functions on a single die: a precision bandgap-based voltage monitor with 4.40V reset threshold and 40mV hysteresis; a p-channel MOSFET-based battery switchover circuit with 5Ω (VCC→VOUT) and 80Ω (VBATT→VOUT) on-resistance paths; a 1.25V reference comparator for PFI/PFO power-fail signaling; and a debounced TTL/CMOS-compatible MR input with 250µA internal pullup.
Its architecture ensures fail-safe operation during brownouts: RESET remains asserted as long as VCC stays below 4.40V, and the internal timer restarts on each voltage dip, guaranteeing ≥140ms (min) / 200ms (typ) / 280ms (max) reset pulse width after recovery. In battery-backup mode (VCC < VRST), the substrate connects to VBATT, disabling PFI/PFO/MR and forcing RESET low while VOUT tracks VBATT – 0.1V at 250µA load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.40V (min 4.25V, max 4.50V); ensures reliable μP reset before +5V supply dropout affects logic integrity |
| Reset Pulse Width | 200ms typical; guarantees sufficient time for μP initialization and peripheral stabilization after power recovery |
| Supply Current | 200µA typical at +25°C; enables low-power system monitoring without burdening main supply |
| Battery-Backup Current | 50nA typical; preserves lithium battery life for years in standby memory retention applications |
| VOUT Output Voltage | VCC – 0.025V at 5mA (active mode); minimizes voltage drop to CMOS RAM during normal operation |
| Battery Switchover Hysteresis | 40mV; prevents oscillatory switching between VCC and VBATT during slow VCC decay near threshold |
| Operating Temperature | 0°C to +70°C; validated for commercial-grade embedded controllers and instrumentation |
Pinout & Package
MAX704CPA+ is housed in an 8-pin plastic dual in-line package (PDIP) with 0.3-inch body width and standard through-hole footprint. Pin 1 is marked by a notch or dot; pins are numbered counterclockwise from top-left when viewed from top.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VOUT | Supply output for CMOS RAM | Switches between VCC (via 5Ω p-MOSFET) and VBATT (via 80Ω p-MOSFET) based on reset threshold crossing |
| 2 VCC | +5V supply input | Main system power input; monitored for reset generation and used as reference for all internal circuits |
| 3 GND | Ground reference | Common return path for all currents; must be low-impedance to ensure accurate threshold detection |
| 4 PFI | Power-fail comparator input | Accepts external voltage divider to trigger PFO low when monitored supply falls below 1.25V |
| 5 PFO | Power-fail comparator output | Open-drain output that sinks current when PFI < 1.25V; disabled in 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 open-drain output asserted when VCC < 4.40V or MR pulled low; guaranteed valid down to VCC = 1V |
| 8 VBATT | Backup-battery input | Accepts 3.0–3.6V lithium battery or supercap; enables automatic RAM power switchover during main supply failure |
Key Features
| Feature | Design Value |
|---|---|
| Precision 4.40V reset threshold | Guaranteed ±150mV tolerance over temperature ensures deterministic μP startup timing across 0°C–70°C |
| 200ms reset pulse width | Eliminates need for external RC timing components while meeting μP minimum reset duration requirements |
| 50nA battery-backup quiescent current | Extends 3.6V lithium battery life beyond 10 years in static RAM retention applications |
| Guaranteed RESET assertion to VCC = 1V | Prevents spurious release of reset during deep brownout, ensuring μP remains held until stable supply returns |
| Debounced manual reset input | Internal 250µA pullup and 200ms timer eliminate need for external debounce circuitry on pushbutton switches |
Applications
| Industrial Controllers | Embedded Instrumentation |
|---|---|
Use Scenario: PLCs and motor controllers requiring nonvolatile RAM retention during AC line interruptions. IC Role / Device Role / Timing Role: Supervisory circuit providing battery-backed VOUT and brownout-triggered RESET to preserve program state and prevent erratic actuator behavior. Use Value: Enables seamless switchover to 3.6V lithium battery within 20mV hysteresis window, maintaining RAM voltage above 2.7V for >10 years at 50nA draw. | Use Scenario: Portable multimeters and data loggers needing accurate power-fail warning before shutdown. IC Role / Device Role / Timing Role: Dual-role device: monitors main +5V rail via internal 4.40V detector for RESET, and uses external resistor divider on PFI to generate early PFO interrupt at 1.25V reference. Use Value: Provides two independent voltage thresholds - one for hard reset (4.40V), one for graceful save-and-shutdown (programmable via PFI divider), reducing firmware complexity. |
| Critical μP Power Monitoring | Computers & Workstations |
Use Scenario: Medical diagnostic equipment where unexpected reset could compromise patient safety. IC Role / Device Role / Timing Role: Primary reset supervisor asserting active-low RESET signal to μP during VCC brownout, with guaranteed validity down to VCC = 1V. Use Value: Prevents partial execution of safety-critical routines by holding RESET active until supply recovers fully above 4.40V with 200ms post-recovery holdoff. | Use Scenario: Legacy desktop motherboards using CMOS SRAM for BIOS configuration storage. IC Role / Device Role / Timing Role: Battery switchover controller connecting lithium cell to VOUT pin to maintain SRAM voltage during AC power loss. Use Value: Replaces discrete diode-and-switch solutions with integrated 80Ω VBATT→VOUT path, eliminating forward voltage drop and enabling use of lower-voltage batteries (3.0V). |
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 electrical specs but 8-pin SO package; 5.88mW/°C derating vs. PDIP's 9.09mW/°C | Suitable for surface-mount PCBs with space constraints; requires reflow soldering instead of through-hole assembly | Select MAX704CSA+ for automated SMT production; MAX704CPA+ preferred for prototyping, repair, or high-reliability through-hole designs |
| MAX706CPA+ | No battery backup; 4.40V reset only; adds CE write-protect and watchdog timer not present in MAX704CPA+ | Used where memory protection or software timeout supervision is needed, but battery switchover is unnecessary | Choose MAX706CPA+ if system includes external battery management; MAX704CPA+ is mandatory when RAM backup is required |
Compared with MAX704CSA+, MAX704CPA+ offers identical supervision functionality but in a through-hole PDIP package ideal for manual assembly and thermal robustness in industrial environments; compared with MAX706CPA+, it trades watchdog/CE features for integrated battery switchover-making it the sole choice when CMOS RAM retention during power loss is essential.
Availability
MAX704CPA+ is available at Aetrix Electronics and suitable for industrial controllers, embedded instrumentation, critical μP power monitoring, and legacy computer BIOS applications requiring stable component supply and long-term obsolescence support.
Supply support for MAX704CPA+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.
The MAX703/MAX704 product line was designed specifically for cost-sensitive microprocessor systems needing integrated power monitoring, reset generation, and battery-backed RAM support without external components.
FAQ
What is the exact reset threshold voltage for MAX704CPA+ and how tightly is it specified?
The MAX704CPA+ has a nominal reset threshold of 4.40V, with guaranteed minimum and maximum values of 4.25V and 4.50V respectively across the full 0°C to +70°C operating range. This ±150mV tolerance ensures deterministic reset behavior in +5V systems, preventing premature or delayed reset assertion during supply transients. The threshold is internally generated using a precision bandgap reference and is independent of VCC loading or temperature drift within spec.
Can MAX704CPA+ operate with a 3.0V lithium battery and still assert valid RESET down to low VCC?
Yes, the MAX704CPA+ maintains valid RESET output down to VCC = 1V regardless of VBATT voltage, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. When VCC drops below 4.40V, RESET goes low and remains asserted even as VCC falls to 1V. Below 1V, RESET becomes high-impedance-but since most μPs require only a logic-low signal during power-down, this behavior is compatible with standard reset inputs when paired with a 100kΩ pulldown resistor.
How does the battery switchover hysteresis work in MAX704CPA+ and why is it important?
The MAX704CPA+ implements 40mV hysteresis in its battery switchover comparator: VBATT connects to VOUT when VCC falls 20mV below VBATT, and VCC reconnects when it rises 20mV above VBATT. This prevents rapid toggling between sources during slow VCC decay near the threshold-critical for avoiding RAM voltage glitches. Without hysteresis, noise or ripple near the crossover point could cause repeated switching, degrading battery life and risking data corruption in CMOS RAM.
What is the maximum allowable backup battery voltage for MAX704CPA+ and what happens if exceeded?
The maximum allowable backup battery voltage for MAX704CPA+ is 4.55V, as specified in Table 2 of the datasheet. Exceeding this risks forward biasing internal substrate diode D1 (between VBATT and the die substrate) when VCC is near the reset threshold, causing unwanted current flow from VBATT into the substrate. This can elevate quiescent current, reduce battery life, and potentially damage the device over time. Lithium cells (3.0–3.6V) and properly sized supercaps remain safely within this limit.
Does MAX704CPA+ support power-fail warning for supplies other than +5V, and how is it configured?
Yes, the MAX704CPA+ supports power-fail warning for any DC supply via its PFI (Power-Fail Input) pin, which compares the applied voltage against an internal 1.25V reference. To monitor a non-+5V rail (e.g., +3.3V or –5V), an external resistor divider scales the target voltage so that it equals 1.25V at the desired trip point. For negative supplies, Figure 8 in the datasheet shows an inverting configuration using two resistors. PFO then asserts low when the scaled input falls below 1.25V, providing an interrupt-capable warning signal.
MAX704CPA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Battery Backup Circuit
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.4V
- 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:
- 8-PDIP
MAX704CPA+ FAQ
1.How can I place an order for MAX704CPA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX704CPA+ 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 MAX704CPA+ reliable?
The price and inventory of MAX704CPA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX704CPA+ is usually 5 days.
3.What payment methods are accepted for MAX704CPA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX704CPA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX704CPA+?
MAX704CPA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX704CPA+ 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 MAX704CPA+?
For technical support, including MAX704CPA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX704CPA+ requirements.
6.How does Aetrix verify that MAX704CPA+ is sourced from the original manufacturer or authorized distributors?
All MAX704CPA+ 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 MAX704CPA+ meets industry standards.
7.What is the process for return or replacement of MAX704CPA+?
All MAX704CPA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX704CPA+, 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 MAX704CPA+ part is unused and in its original packaging.
Return procedure for MAX704CPA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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