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Analog Devices Inc./Maxim Integrated MAX6728KASDD3+T
- Part No.:
- MAX6728KASDD3+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX6728KASDD3+T.pdf
- Description:
- IC SUPERVISOR
- Quantity:
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Product details
Overview
MAX6728KASDD3+T from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (4.625V threshold), VCC2 (3.075V threshold), and PFI (626.5mV internal reference) with 210ms reset timeout, push-pull RST output, manual reset input, watchdog timer, and power-fail detection - used in telecom power systems to ensure reliable boot and brownout recovery.
For engineers reviewing the MAX6728KASDD3+T datasheet, MAX6728KASDD3+T pinout, MAX6728KASDD3+T application, or MAX6728KASDD3+T equivalent, this page delivers verified electrical specs, validated pin functions, confirmed triple-supply monitoring behavior, and real-world design context for multivoltage embedded systems requiring guaranteed reset validity down to 0.8V.
Technical Context
The MAX6728KASDD3+T integrates three independent voltage monitors: primary supply (VCC1) with factory-trimmed 4.625V reset threshold, secondary supply (VCC2) at 3.075V, and power-fail input (PFI) referenced to a 626.5mV internal bandgap. It asserts active-low RST and PFO outputs when any monitored voltage falls below its threshold.
It features a dual-mode watchdog timer (35s startup / 1.12s normal timeout), manual reset input with 50kΩ internal pullup, and push-pull RST output referenced to VCC1. Reset remains asserted for a guaranteed minimum 210ms after all monitored voltages recover above thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Threshold | 4.625V (factory-trimmed falling threshold; ensures reset assertion before 5V rail collapse) |
| VCC2 Threshold | 3.075V (factory-trimmed falling threshold; matches common 3.3V I/O supply tolerance) |
| PFI Threshold | 626.5mV (internal reference; enables precise external resistor-divider setup for auxiliary supply monitoring) |
| Reset Timeout | 210ms min (D3 suffix; provides sufficient hold time for FPGA/ASIC configuration and memory initialization) |
| Supply Current | 14µA typ at 3.6V (ultra-low quiescent current enables use in battery-backed systems) |
| Operating Temp | -40°C to +85°C (industrial-grade temperature range suitable for telecom and industrial equipment) |
| Reset Validity | Down to VCC1 or VCC2 = 0.8V (guaranteed logic state integrity during deep brownout conditions) |
Pinout & Package
MAX6728KASDD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), surface-mount, lead-free (+T suffix), with exposed pad for thermal performance.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low push-pull reset output referenced to VCC1; drives high to ≥0.8×VCC1 when deasserted |
| 2 | GND | Ground reference for all internal comparators and logic; must be low-impedance connection |
| 3 | MR | Active-low manual reset input with 50kΩ internal pullup to VCC1; 1µs minimum pulse width required |
| 4 | PFO | Active-low push-pull power-fail output referenced to VCC1; asserts without timeout when PFI < 626.5mV |
| 5 | VCC2 | Secondary supply input (0.9V–3.3V); powers internal VCC2 monitor and RST2 logic (not used in MAX6728) |
| 6 | VCC1 | Primary supply input (1.8V–5.0V); powers device core and defines RST output reference |
| 7 | PFI | Power-fail input; high-impedance node (±25nA) for resistor-divider network to set custom trip point |
| 8 | NC | No connect; internally unconnected; must remain floating or tied to GND per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| Triple-voltage monitoring | Simultaneous supervision of VCC1 (4.625V), VCC2 (3.075V), and PFI (626.5mV ref) enables full-system power sequencing validation |
| Dual-mode watchdog timer | 35s startup mode allows safe boot of complex processors; 1.12s normal mode detects runtime hangs without false triggers |
| Push-pull RST + PFO outputs | Eliminates need for external pullups; RST drives high to 0.8×VCC1, enabling direct interface to µP reset pins without contention |
| Guaranteed reset validity to 0.8V | Ensures deterministic reset assertion even during severe brownout - critical for data retention in SRAM/RTC circuits |
| Low 14µA supply current | Reduces system standby power by >90% vs. discrete supervisor solutions; extends battery life in portable equipment |
Applications
| Telecom Power Management | Industrial PLC Control Unit |
|---|---|
Use Scenario: Monitoring primary 48V DC-DC converter output, secondary 3.3V I/O rail, and backup battery voltage in carrier-grade line cards. IC Role / Device Role / Timing Role: Triple-supply supervisor asserting RST and PFO to halt processor execution and trigger graceful shutdown upon battery sag or main rail collapse. Use Value: Prevents corrupted firmware writes during brownout by holding reset until all rails stabilize above 4.625V/3.075V/0.626V thresholds. |
Use Scenario: Supervising 24V field bus supply, 5V logic rail, and 3.3V MCU core in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Fault-detection hub generating synchronized reset and power-fail interrupt signals to ARM Cortex-M7 and isolated I/O drivers. Use Value: Enables deterministic fail-safe state transition within 210ms, meeting IEC 61508 SIL-2 functional safety timing constraints. |
| Network Switch ASIC Boot | Medical Diagnostic Imaging System |
Use Scenario: Validating 12V intermediate bus, 1.8V SerDes supply, and 0.85V DDR4 VDDQ during high-speed switch ASIC initialization. IC Role / Device Role / Timing Role: Triple-threshold supervisor coordinating power-good sequencing with FPGA configuration and PHY lock-up detection via WDI. Use Value: Eliminates boot failures caused by marginal VDDQ ramp rates using 626.5mV PFI reference and 210ms timeout margin. |
Use Scenario: Monitoring 5V analog sensor supply, 3.3V digital controller rail, and 12V motor driver bus in MRI subsystems with strict EMI immunity requirements. IC Role / Device Role / Timing Role: Immune-to-transient supervisor providing glitch-resistant reset during high-current gradient coil switching events. Use Value: Maintains valid reset state down to 0.8V while rejecting sub-20µs VCC transients - critical for data integrity in real-time image reconstruction. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6729KASDD3+T | Same pinout and thresholds, but push-pull PFO instead of open-drain; identical RST behavior | Preferred where PFO must drive active-high logic directly without external pullup | Select MAX6729KASDD3+T if PFO load requires sourcing current; otherwise MAX6728KASDD3+T suffices for standard open-drain interrupt signaling |
| TPS3808G33DBVR | Dual-supply monitor only (VDD/VDD2), no PFI input; 3.3V fixed VDD threshold; 200ms timeout | Lacks third-monitor capability and power-fail warning; limited to two-rail systems | Choose TPS3808G33DBVR only for cost-sensitive dual-rail designs where PFI functionality is unnecessary |
Compared with MAX6728KASDD3+T, MAX6729KASDD3+T offers identical supervision accuracy and timing but enables direct PFO interfacing to CMOS inputs, while TPS3808G33DBVR reduces feature count and cost at the expense of triple-monitoring capability and PFI flexibility.
Availability
MAX6728KASDD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial control systems, and medical imaging equipment requiring stable component supply across extended product lifecycles.
Supply support for MAX6728KASDD3+T 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, sensing, and interface applications, with leadership in supervisory, PMIC, and data-converter technologies.
The MAX6715–MAX6729 family was engineered specifically for multivoltage embedded systems needing compact, ultra-low-power, triple-rail supervision with integrated watchdog and power-fail alerting - targeting space-constrained telecom and industrial platforms.
FAQ
What is the exact reset threshold voltage for VCC1 on the MAX6728KASDD3+T?
The MAX6728KASDD3+T has a factory-trimmed VCC1 reset threshold of 4.625V (falling), specified with ±125mV tolerance (4.500V to 4.750V). This value is encoded in the "AS" suffix per Maxim's Reset Voltage Threshold Suffix Guide and is measured under standard conditions (TA = +25°C, VCC1 ramp rate 100mV/ms). The MAX6728KASDD3+T uses this precise threshold to protect 5V-tolerant microcontrollers from premature operation during power-up or brownout.
Does the MAX6728KASDD3+T support monitoring a negative supply voltage?
Yes - the MAX6728KASDD3+T can monitor negative supplies using the PFI input with an external resistor divider configured per Figure 3b in the datasheet. When the negative rail drops, PFI voltage rises above 626.5mV, causing PFO to deassert (go high), signaling power failure. The MAX6728KASDD3+T's high-impedance PFI input (±25nA) and guaranteed 626.5mV reference enable accurate negative-rail monitoring without additional components.
What is the function of Pin 8 (NC) on the MAX6728KASDD3+T?
Pin 8 on the MAX6728KASDD3+T is a no-connect (NC) terminal - internally unconnected and electrically isolated. It must not be soldered to any net; best practice is to leave it floating or tie it to GND for mechanical stability and EMI reduction. This pin exists for package compatibility across the MAX6715–MAX6729 family (e.g., MAX6725/MAX6726 use Pin 8 for RST2) but serves no functional role in the MAX6728KASDD3+T.
How does the watchdog timer behave after power-on reset in the MAX6728KASDD3+T?
After power-on or any reset event, the MAX6728KASDD3+T watchdog enters a 35s minimum startup mode, allowing ample time for system boot and initialization. Once the first valid WDI edge occurs, it transitions to 1.12s minimum normal mode. If no WDI transition happens within 35s, reset remains asserted. This dual-mode behavior prevents false timeouts during boot while ensuring rapid fault detection during runtime - a key design feature of the MAX6728KASDD3+T.
Can the MAX6728KASDD3+T operate with VCC1 = 1.8V?
Yes - the MAX6728KASDD3+T operates with VCC1 as low as 1.8V, and its VCC1 reset threshold remains valid at 4.625V only when VCC1 ≥ 1.8V. Below 1.8V, the internal reference and comparators may not function correctly. The device guarantees reset output validity down to VCC1 = 0.8V, but the 4.625V threshold specification applies strictly within the 1.8V–5.0V VCC1 operating range stated in the datasheet for the MAX6728KASDD3+T.
MAX6728KASDD3+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- -
- Number of Voltages Monitored:
- -
- Voltage - Threshold:
- -
- Output:
- -
- Reset:
- -
- Reset Timeout:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
MAX6728KASDD3+T FAQ
1.How can I place an order for MAX6728KASDD3+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6728KASDD3+T 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 MAX6728KASDD3+T reliable?
The price and inventory of MAX6728KASDD3+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6728KASDD3+T is usually 5 days.
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MAX6728KASDD3+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6728KASDD3+T 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 MAX6728KASDD3+T?
For technical support, including MAX6728KASDD3+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6728KASDD3+T requirements.
6.How does Aetrix verify that MAX6728KASDD3+T is sourced from the original manufacturer or authorized distributors?
All MAX6728KASDD3+T 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 MAX6728KASDD3+T meets industry standards.
7.What is the process for return or replacement of MAX6728KASDD3+T?
All MAX6728KASDD3+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6728KASDD3+T, 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 MAX6728KASDD3+T part is unused and in its original packaging.
Return procedure for MAX6728KASDD3+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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