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Analog Devices Inc./Maxim Integrated MAX6728KASHD3+T
- Part No.:
- MAX6728KASHD3+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX6728KASHD3+T.pdf
- Description:
- MAX6728KASHD3+T
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Product details
Overview
MAX6728KASHD3+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 and open-drain PFO outputs, and guaranteed reset validity down to VCC1 or VCC2 = 0.8V - used in telecom power management and industrial multivoltage systems.
For engineers reviewing the MAX6728KASHD3+T datasheet, MAX6728KASHD3+T pinout, MAX6728KASHD3+T application, or MAX6728KASHD3+T equivalent, key selection factors include its dual-supply monitoring capability with factory-trimmed thresholds, integrated power-fail comparator with PFO output, watchdog timer support, manual reset input, and operation across –40°C to +85°C.
Technical Context
The MAX6728KASHD3+T implements independent voltage monitoring for primary (VCC1), secondary (VCC2), and auxiliary (PFI) rails using precision bandgap references and hysteresis-controlled comparators. Its reset logic asserts active-low RST when any monitored voltage falls below its threshold and holds for a fixed 210ms timeout after recovery.
It integrates a power-fail comparator with 2µs propagation delay from PFI to PFO, supports manual reset via MR with internal 50kΩ pullup, and guarantees valid reset state even when VCC1 or VCC2 drops to 0.8V - enabling robust brownout detection in battery-backed and distributed power systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Reset Threshold | 4.625V (factory-trimmed, ±125mV tolerance) - sets precise brownout point for main system rail |
| VCC2 Reset Threshold | 3.075V (factory-trimmed, ±75mV tolerance) - monitors secondary supply such as I/O or memory voltage |
| PFI Input Threshold | 626.5mV (internal reference) - enables external resistor-divider to monitor third supply down to 0.62V |
| Reset Timeout Period | 210ms (min) - ensures sufficient hold time for processor initialization and peripheral stabilization |
| Supply Current | 14µA (typ at 3.6V) - ultra-low quiescent current extends battery life in portable equipment |
| Operating Temperature | –40°C to +85°C - qualified for industrial and telecom environments without derating |
| Reset Output Type | Push-pull RST, open-drain PFO - eliminates need for external pullups on RST; PFO requires external pullup |
Pinout & Package
MAX6728KASHD3+T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm), optimized for high-density PCB layouts and reflow-compatible assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low push-pull reset output - drives low during fault; no external pullup required |
| 2 | GND | Ground reference for all internal circuits and comparators |
| 3 | MR | Active-low manual reset input with internal 50kΩ pullup to VCC1 - debounced by design |
| 4 | PFO | Active-low open-drain power-fail output - requires external pullup; asserts when PFI < 626.5mV |
| 5 | VCC2 | Secondary supply input (0.9V–3.3V range) - powers internal VCC2 comparator and sets RST2 reference |
| 6 | VCC1 | Primary supply input (1.8V–5.0V range) - powers core logic and sets RST reference |
| 7 | PFI | Power-fail monitor input - high-impedance node for resistor-divider network to set custom trip point |
| 8 | NC | No connect - internally unused; must be left floating or tied to GND per layout best practice |
Key Features
| Feature | Design Value |
|---|---|
| Triple-voltage supervision | Simultaneous monitoring of VCC1, VCC2, and PFI with independent thresholds - eliminates need for multiple discrete supervisors |
| Guaranteed reset validity to 0.8V | Ensures reliable reset assertion even during deep brownout conditions where VCC1 or VCC2 dips near 0.8V |
| Integrated power-fail comparator | 2µs PFI-to-PFO delay with 3mV hysteresis - enables fast, noise-immune early warning of supply collapse |
| Manual reset with internal pullup | 50kΩ internal MR pullup to VCC1 - simplifies board design by removing external resistor |
| Low supply current | 14µA typical at 3.6V - reduces system-level power budget impact in always-on monitoring applications |
Applications
| Telecom Power Sequencing | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Monitoring primary 4.8V DC-DC output, secondary 3.3V FPGA I/O rail, and backup battery voltage in LTE base station power management. IC Role / Device Role / Timing Role: Triple-supply supervisor asserting synchronized reset and PFO interrupt to enable graceful shutdown before battery depletion. Use Value: Prevents firmware corruption during brownout by holding reset for 210ms while ensuring PFO triggers host MCU interrupt within 2µs of PFI crossing threshold. |
Use Scenario: Supervising 24V field bus supply (via resistor divider), 5V logic rail, and 3.3V microcontroller core in modular PLC backplane. IC Role / Device Role / Timing Role: Fault detector providing isolated reset signaling and power-fail alert to safety controller via PFO. Use Value: Enables deterministic response to undervoltage events with 210ms reset hold time and sub-3µs PFI-to-PFO latency - meeting IEC 61508 functional safety timing constraints. |
| Medical Diagnostic Imaging | Network Edge Router |
Use Scenario: Validating 12V analog sensor supply, 5V ADC reference rail, and 3.3V SoC core voltage in portable ultrasound subsystem. IC Role / Device Role / Timing Role: System integrity guardian asserting RST and PFO to halt imaging acquisition and preserve calibration data during supply sag. Use Value: Guarantees reset remains valid down to 0.8V on any monitored rail - critical for maintaining safe state during transient line disturbances. |
Use Scenario: Monitoring 48V PoE input (via PFI divider), 12V intermediate rail, and 1.8V CPU core in compact edge router. IC Role / Device Role / Timing Role: Multirail supervisor coordinating power sequencing and triggering PFO-based NMI to initiate firmware rollback on PoE interruption. Use Value: Combines 4.625V/3.075V factory-trimmed thresholds with 210ms timeout to meet IEEE 802.3af/bt power-loss recovery requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6729KASHD3+T | Push-pull PFO output (vs. open-drain in MAX6728KASHD3+T); identical VCC1/VCC2 thresholds and timeout | Eliminates need for external PFO pullup resistor; better suited for direct interface to CMOS inputs | Select MAX6729KASHD3+T when PFO must drive CMOS logic without external components |
| TPS3808G33DBVR | Dual-supply only (VDD, VDDIO), no PFI input; 3.3V fixed VDD threshold, 200ms timeout, 1.6µA supply current | Lacks third-voltage monitoring and power-fail functionality; optimized for ultra-low-power single-rail systems | Choose TPS3808G33DBVR only if triple-monitoring is unnecessary and sub-2µA quiescent current is mandatory |
Compared with MAX6728KASHD3+T, MAX6729KASHD3+T offers identical supervision accuracy and timing but adds push-pull PFO for simplified interfacing, while TPS3808G33DBVR trades third-rail capability for lower power - making MAX6728KASHD3+T optimal for applications requiring PFI-based auxiliary monitoring with minimal BOM overhead.
Availability
MAX6728KASHD3+T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial control, medical diagnostics, and network edge equipment requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to +85°C.
Supply support for MAX6728KASHD3+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, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.
The MAX6715–MAX6729 family delivers ultra-low-voltage, multirail supervision in miniature SOT23 packages - engineered specifically for space-constrained, multivoltage systems needing reliable power-up sequencing and brownout protection.
FAQ
What is the exact reset timeout period for MAX6728KASHD3+T?
The MAX6728KASHD3+T has a minimum reset timeout period of 210ms, as indicated by the "D3" suffix in its part number. This value is factory-trimmed and guaranteed over temperature (–40°C to +85°C) and supply voltage (0.8V to 5.5V). The actual timeout may vary slightly due to process and temperature, but remains ≥210ms under all specified operating conditions - ensuring sufficient hold time for processor initialization sequences.
Does MAX6728KASHD3+T support monitoring a negative supply voltage?
Yes, MAX6728KASHD3+T can monitor a negative supply using the PFI input with an appropriate resistor-divider configuration as shown in Figure 3b of the datasheet. When the negative supply is valid, PFO asserts low; as the supply collapses, PFO deasserts. Accuracy depends on PFI threshold tolerance (±15.5mV), resistor matching, and VCC stability - and the device guarantees correct operation down to VCC1 or VCC2 = 0.8V during this monitoring.
What is the function of Pin 8 (NC) on MAX6728KASHD3+T?
Pin 8 on MAX6728KASHD3+T is a no-connect (NC) terminal - it is not bonded internally and serves no electrical function. Per Maxim's layout guidance, it should be left unconnected or tied to GND to improve thermal dissipation and reduce noise coupling. It must never be connected to VCC or driven externally, as this could compromise ESD robustness or cause undefined behavior in adjacent pins.
Can MAX6728KASHD3+T be used without connecting the MR pin?
Yes, MAX6728KASHD3+T can operate without external connection to the MR pin because it features an internal 50kΩ pullup resistor to VCC1. Leaving MR unconnected defaults it to logic-high, disabling manual reset. If MR is unused, no external components are required - though in noisy environments, a 0.1µF capacitor from MR to GND is recommended for added immunity against false resets.
How does the PFI-to-PFO propagation delay affect system response time in MAX6728KASHD3+T?
The PFI-to-PFO propagation delay in MAX6728KASHD3+T is 2µs (typical), measured from PFI crossing 626.5mV to PFO transitioning low. This sub-microsecond latency enables rapid power-fail detection - critical for initiating controlled shutdowns in systems like telecom equipment or medical devices. The delay remains stable across temperature and supply voltage, supporting deterministic real-time response without software intervention.
MAX6728KASHD3+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:
- -
MAX6728KASHD3+T FAQ
1.How can I place an order for MAX6728KASHD3+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6728KASHD3+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 MAX6728KASHD3+T reliable?
The price and inventory of MAX6728KASHD3+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6728KASHD3+T is usually 5 days.
3.What payment methods are accepted for MAX6728KASHD3+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6728KASHD3+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6728KASHD3+T?
MAX6728KASHD3+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6728KASHD3+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 MAX6728KASHD3+T?
For technical support, including MAX6728KASHD3+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6728KASHD3+T requirements.
6.How does Aetrix verify that MAX6728KASHD3+T is sourced from the original manufacturer or authorized distributors?
All MAX6728KASHD3+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 MAX6728KASHD3+T meets industry standards.
7.What is the process for return or replacement of MAX6728KASHD3+T?
All MAX6728KASHD3+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6728KASHD3+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 MAX6728KASHD3+T part is unused and in its original packaging.
Return procedure for MAX6728KASHD3+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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