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Analog Devices Inc./Maxim Integrated MAX703CSA+
- Part No.:
- MAX703CSA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX703CSA+.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,566
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Product details
Overview
MAX703CSA+ from Maxim Integrated is a microprocessor supervisory circuit designed for power-supply monitoring and battery-backup switching in +5V μP systems. It provides active-low reset assertion below 4.65V, 200ms reset pulse width, 1.25V power-fail comparator input, debounced manual reset input, and automatic switchover to backup battery (VBATT) when VCC drops below reset threshold - used in embedded controllers requiring reliable brownout protection and CMOS RAM retention.
For engineers reviewing the MAX703CSA+ datasheet, MAX703CSA+ pinout, MAX703CSA+ application, or MAX703CSA+ equivalent, key selection criteria include guaranteed RESET assertion down to VCC = 1V, 5Ω VOUT switch resistance under VCC supply, 80Ω switch resistance in battery-backup mode, quiescent current of 200µA (normal) and 50nA (backup), and compatibility with lithium batteries (3.0–3.6V) or supercaps as backup sources.
Technical Context
The MAX703CSA+ integrates four core functions: precision supply-voltage monitoring with 4.65V reset threshold and 40mV hysteresis; battery-switchover logic that connects VBATT to VOUT only when VCC falls below VRST and VBATT exceeds VCC by ≥20mV; a 1.25V reference-based power-fail comparator (PFI/PFO); and TTL/CMOS-compatible manual reset input with internal 250µA pullup.
Its internal architecture includes a p-channel MOSFET power switch (5Ω on-resistance in VCC mode, 80Ω in VBATT mode), a reset timer with 140–280ms pulse width (typ. 200ms), and automatic disable of PFI comparator and MR functionality during battery-backup mode - ensuring minimal current draw (<1µA) when VCC is >1V below VBATT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V ±150mV - asserts active-low RESET when VCC drops below this level; enables reliable brownout detection for +5V systems. |
| Reset Pulse Width | 200ms typ. - ensures μP completes full initialization before release; minimum 140ms guarantees timing margin across temperature. |
| VOUT Switch Resistance | 5Ω (VCC mode), 80Ω (VBATT mode) - determines voltage drop under load: <25mV at 5mA (VCC), <200mV at 250µA (VBATT). |
| Quiescent Current | 200µA (normal operation), 50nA (battery-backup mode) - enables multi-year battery life in RAM-retention applications. |
| Power-Fail Comparator Threshold | 1.25V ±50mV - allows external resistor divider to monitor unregulated supplies or negative rails with predictable trip point. |
| Manual Reset Input | TTL/CMOS-compatible, 0.8V low threshold, 250µA internal pullup - supports direct pushbutton or logic-level assertion without external components. |
| Operating Temperature | 0°C to +70°C - specified for commercial-grade industrial and computing applications with stable thermal environments. |
Pinout & Package
MAX703CSA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant (indicated by '+' suffix), with 1.27mm lead pitch and surface-mount land pattern 90-0096 per Maxim document 21-0041.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VOUT | Supply output for CMOS RAM or low-power logic | Switched between VCC (via 5Ω p-MOSFET) or VBATT (via 80Ω p-MOSFET) depending on supply status; maintains memory power during brownout. |
| 2 - VCC | +5V main supply input | Primary power source; monitored for reset generation; powers internal circuitry unless in battery-backup mode. |
| 3 - GND | Circuit ground reference | Common return path for all analog and digital functions; substrate connection point in normal operation. |
| 4 - PFI | Power-fail comparator input | Monitors external voltage divider; triggers PFO low when input falls below 1.25V - used for early power-fail warning or negative rail monitoring. |
| 5 - PFO | Power-fail comparator output | Active-low open-drain output; disabled and forced low during battery-backup mode to prevent spurious interrupts. |
| 6 - MR | Manual reset input | Active-low TTL/CMOS-compatible input; internally pulled up to ~2.5V; debounced by 200ms reset timer - eliminates need for external RC network. |
| 7 - RESET | Reset output signal | Active-low push-pull output; asserted while VCC < 4.65V or MR is low; guaranteed functional down to VCC = 1V; sinks 3.2mA min. |
| 8 - VBATT | Backup battery input | Accepts 2.8–4.8V lithium or supercap source; enables automatic switchover when VCC fails; draws <1µA if VCC < VBATT −1V. |
Key Features
| Feature | Design Value |
|---|---|
| Battery-backup switchover | Automatic, hysteresis-controlled (±20mV) switching between VCC and VBATT at VOUT - prevents oscillation during slow VCC decay and preserves RAM data without software intervention. |
| Precision reset threshold | 4.65V ±150mV over 0°C to +70°C - eliminates need for external voltage reference or trimming in cost-sensitive μP systems. |
| Guaranteed RESET down to VCC = 1V | Ensures valid reset signaling even during deep brownout; avoids undefined μP states when supply collapses gradually. |
| Low-quiescent-current battery mode | 50nA typical supply current when VCC = 0V and VBATT = 2.8V - extends lithium battery life beyond 10 years in static RAM applications. |
| Integrated power-fail comparator | 1.25V internal reference with <25nA input bias - enables accurate undervoltage detection of auxiliary supplies using only two external resistors. |
Applications
| Industrial Controllers | Embedded Data Loggers |
|---|---|
Use Scenario: Programmable logic controllers (PLCs) operating in factory environments with fluctuating 5V rail stability. IC Role / Device Role / Timing Role: Supervisory circuit providing brownout reset, RAM backup switchover, and early power-fail warning via PFI/PFO. Use Value: Prevents corrupted control state during line sags; retains configuration and runtime variables using onboard lithium battery without external supervision logic. |
Use Scenario: Battery-powered environmental sensors logging temperature/humidity at fixed intervals over months. IC Role / Device Role / Timing Role: Ensures clean μP startup after wake-up from deep sleep; maintains SRAM contents during main supply interruption. Use Value: Enables zero-software overhead RAM retention with <50nA backup current - extends operational lifetime beyond 5 years on a single CR2032 cell. |
| Medical Diagnostic Equipment | Point-of-Sale Terminals |
Use Scenario: Portable ultrasound or ECG units requiring deterministic boot sequence and nonvolatile parameter storage. IC Role / Device Role / Timing Role: Generates 200ms reset pulse synchronized to VCC rise; switches VOUT to VBATT during AC adapter disconnect. Use Value: Guarantees μP enters known state before firmware execution; preserves calibration coefficients and patient history in SRAM during hot-swap battery changes. |
Use Scenario: Retail terminals powered from wall adapters with occasional grid instability or cable disconnection. IC Role / Device Role / Timing Role: Monitors +5V rail for brownout; asserts RESET and activates battery-backed VOUT to sustain real-time clock and transaction buffer. Use Value: Eliminates transaction loss during brief outages; avoids EEPROM wear from frequent save operations by retaining volatile buffers in battery-backed RAM. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX704CSA+ | 4.40V reset threshold (vs. 4.65V), identical pinout, timing, and features | Suitable for systems with tighter +5V tolerance (±10%) or lower dropout regulators | Select MAX704CSA+ when main supply nominal is 5.0V ±10% and brownout must trigger earlier than 4.65V. |
| MAX705CPA+ | No battery backup; adds watchdog timer and CE write-protect; 8-pin PDIP only | Used where RAM retention is unnecessary but system-level fault recovery (watchdog timeout) is required | Choose MAX705CPA+ for cost-optimized designs needing watchdog reset but no VBATT support - requires PCB redesign due to DIP vs. SO package. |
Compared with MAX703CSA+, MAX704CSA+ offers earlier reset activation for wider supply tolerances but identical reliability and battery management; MAX705CPA+ trades battery switchover for watchdog functionality and uses a through-hole package, limiting suitability for space-constrained SMT layouts.
Availability
MAX703CSA+ is available at Aetrix Electronics and suitable for industrial controllers, embedded data loggers, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MAX703CSA+ 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, mixed-signal, and power-management ICs for industrial, computing, and communications applications.
The MAX703/MAX704 product line delivers low-cost, integrated supervisory solutions targeting μP-based systems needing reliable power monitoring, battery-backed RAM retention, and minimal external components - optimized for commercial-temperature embedded control.
FAQ
What is the guaranteed reset assertion voltage range for MAX703CSA+?
The MAX703CSA+ guarantees RESET assertion while VCC remains below 4.65V ±150mV across 0°C to +70°C. Crucially, it continues to drive RESET low down to VCC = 1V, ensuring deterministic behavior during deep brownout conditions where many supervisors lose output control. This specification is confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables of the official datasheet.
Can MAX703CSA+ be used with a 3.6V lithium battery without additional circuitry?
Yes, MAX703CSA+ supports direct connection of 3.0V–3.6V lithium batteries to the VBATT pin. Its internal switchover comparator and 80Ω p-MOSFET switch enable seamless transition to battery power when VCC drops below 4.65V. The device draws only 50nA in battery-backup mode, making it ideal for multi-year operation on a single CR2032 cell - no diodes, regulators, or charge controllers required.
How does the power-fail comparator (PFI/PFO) function in MAX703CSA+?
The MAX703CSA+ PFI input compares against a precise 1.25V internal reference. When PFI voltage falls below 1.25V, PFO goes low - enabling early warning of power failure before VCC reaches the 4.65V reset threshold. In battery-backup mode, the comparator is disabled and PFO is forced low to prevent false interrupts. This dual-mode operation ensures robustness across both main and backup power states.
What is the maximum allowable backup-battery voltage for MAX703CSA+?
The maximum allowable backup-battery voltage for MAX703CSA+ is 4.80V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1 in Figure 3) when VCC is near the reset threshold, causing unwanted current flow from VBATT to VCC and potential damage or erratic behavior. For supercapacitor use, this limit constrains charging voltage to ≤4.80V.
Does MAX703CSA+ require external components for manual reset functionality?
No, MAX703CSA+ includes an internal 250µA pullup current on the MR pin, making it fully functional with only a momentary switch to ground. The 200ms minimum reset pulse width inherently debounces mechanical switch bounce, eliminating the need for external RC filters or Schmitt-trigger circuits. This simplifies board layout and reduces BOM count while maintaining robust reset initiation.
MAX703CSA+ 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:
- 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:
- 8-SOIC
MAX703CSA+ FAQ
1.How can I place an order for MAX703CSA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX703CSA+ 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 MAX703CSA+ reliable?
The price and inventory of MAX703CSA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX703CSA+ is usually 5 days.
3.What payment methods are accepted for MAX703CSA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX703CSA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX703CSA+?
MAX703CSA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX703CSA+ 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 MAX703CSA+?
For technical support, including MAX703CSA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX703CSA+ requirements.
6.How does Aetrix verify that MAX703CSA+ is sourced from the original manufacturer or authorized distributors?
All MAX703CSA+ 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 MAX703CSA+ meets industry standards.
7.What is the process for return or replacement of MAX703CSA+?
All MAX703CSA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX703CSA+, 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 MAX703CSA+ part is unused and in its original packaging.
Return procedure for MAX703CSA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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