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Analog Devices Inc./Maxim Integrated MAX6728KALTD3-T
- Part No.:
- MAX6728KALTD3-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6728KALTD3-T.pdf
- Description:
- IC SUPERVISOR MPU
- Quantity:
- Payment:
- Shipping:
Inventory:6,900
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Product details
Overview
MAX6728KALTD3-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 minimum reset timeout, 14µA typical supply current at 3.6V, and guaranteed reset validity down to VCC1 or VCC2 = 0.8V - used in telecom power sequencing and industrial multivoltage systems.
For engineers reviewing the MAX6728KALTD3-T datasheet, MAX6728KALTD3-T pinout, MAX6728KALTD3-T application, or MAX6728KALTD3-T equivalent, key selection criteria include its dual-supply monitoring capability, integrated power-fail comparator with open-drain PFO output, manual reset input with 50kΩ internal pullup, watchdog timer with 35s startup/1.12s normal mode, and compatibility with low-voltage core/logic rails (0.9V–5.0V).
Technical Context
The MAX6728KALTD3-T implements three independent voltage monitoring paths: primary (VCC1), secondary (VCC2), and auxiliary power-fail (PFI), each feeding dedicated comparators referenced to factory-trimmed thresholds. Its reset logic asserts active-low RST and PFO outputs when any monitored rail falls below its threshold, maintaining assertion for a fixed 210ms timeout after recovery.
It integrates a dual-mode watchdog timer (35s min startup, 1.12s min normal), manual reset input with glitch rejection (100ns), and push-pull RST output referenced to VCC1 - all operating across –40°C to +85°C with supply current stable under temperature variation (14µA typ at +25°C, ≤18µA max over full range).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Reset Threshold | 4.625V (factory-trimmed, ±125mV tolerance) - sets reliable brownout detection for 5V system rails |
| VCC2 Reset Threshold | 3.075V (factory-trimmed, ±75mV tolerance) - monitors 3.3V I/O or intermediate supply with hysteresis |
| PFI Threshold Voltage | 626.5mV (internal reference, ±15.5mV) - enables precise external resistor-divider setup for custom power-fail trip points |
| Reset Timeout Period | 210ms (minimum) - ensures sufficient hold time for processor initialization and peripheral stabilization |
| Supply Current | 14µA (typical at 3.6V, +25°C) - supports ultra-low-power battery-backed or always-on monitoring applications |
| Operating Temperature | –40°C to +85°C - qualified for industrial and telecom equipment deployed in uncontrolled environments |
| Reset Output Type | Push-pull RST, open-drain PFO - eliminates need for external pullups on RST while allowing flexible PFO interfacing |
Pinout & Package
MAX6728KALTD3-T is housed in an 8-pin SOT23-8 package (2.0mm × 2.1mm × 1.25mm body, 0.65mm pitch), optimized for high-density PCB layouts in space-constrained telecom and portable systems.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low push-pull reset output referenced to VCC1; asserts when VCC1/VCC2/PFI fault or MR low; holds for 210ms post-recovery |
| 2 | GND | Analog/digital ground reference for all internal comparators, timers, and output drivers |
| 3 | MR | Active-low manual reset input with 50kΩ internal pullup to VCC1; 1µs minimum pulse width; immune to <100ns glitches |
| 4 | PFO | Active-low open-drain power-fail output; asserts immediately (2µs delay) when PFI < 626.5mV; no timeout, deasserts synchronously |
| 5 | VCC2 | Secondary supply input (0.9V–3.3V range); powers internal circuitry when > VCC1 and sets VCC2 reset threshold |
| 6 | VCC1 | Primary supply input (1.8V–5.0V range); powers device when > VCC2 and sets VCC1 reset threshold |
| 7 | PFI | Power-fail monitor input; high-impedance (±25nA) node for resistor-divider network; triggers PFO when voltage drops below 626.5mV |
| 8 | NC | No-connect pin - left unconnected per datasheet; not internally bonded |
Key Features
| Feature | Design Value |
|---|---|
| Triple-voltage supervision | Simultaneous monitoring of VCC1 (4.625V), VCC2 (3.075V), and PFI (626.5mV) enables robust power sequencing in multirail SoC systems |
| Integrated power-fail comparator | Dedicated PFI/PFO path provides immediate, timeout-free power-fail signaling for orderly shutdown or backup activation |
| Dual-mode watchdog timer | 35s startup window allows full system boot before enabling 1.12s normal watchdog - prevents false resets during initialization |
| Guaranteed reset validity to 0.8V | Ensures clean, predictable reset assertion even during deep brownout conditions where VCC1 or VCC2 dips near 0.8V |
| Low quiescent current | 14µA typical ICC at 3.6V enables years of operation on coin-cell batteries in always-on monitoring nodes |
Applications
| Telecom Power Sequencing | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Monitoring 48V DC-DC converter output (VCC1), isolated 3.3V logic rail (VCC2), and backup battery voltage (via PFI) in remote radio units. IC Role / Device Role / Timing Role: Triple-supply supervisor enforcing strict power-up order, detecting undervoltage on critical rails, and triggering PFO-driven battery switchover within 2µs. Use Value: Prevents firmware corruption during AC mains dropout by asserting RST before VCC1 collapses below 4.625V and initiating graceful fallback via PFO interrupt. |
Use Scenario: Supervising 24V field bus supply (VCC1), 5V controller rail (VCC2), and 12V analog sensor excitation (via PFI) in modular I/O chassis. IC Role / Device Role / Timing Role: Fault detector that latches reset until all three supplies stabilize above thresholds, with PFO signaling analog supply degradation prior to digital failure. Use Value: Enables predictive maintenance by using PFI voltage trend analysis (via µP ADC) to flag aging power supplies before catastrophic failure occurs. |
| Network Switch ASIC Power Management | Medical Diagnostic Imaging Subsystem |
|
Use Scenario: Coordinating power sequencing for multi-core switch ASIC (VCC1 = 1.2V core, VCC2 = 1.8V I/O) and auxiliary 3.3V management rail (PFI). IC Role / Device Role / Timing Role: System-level reset arbiter ensuring ASIC core powers up fully before I/O and management interfaces are enabled. Use Value: Eliminates timing race conditions between voltage ramps by enforcing 210ms interlock between VCC1/VCC2 stabilization and RST deassertion. |
Use Scenario: Monitoring FPGA core (VCC1 = 1.0V), I/O bank (VCC2 = 2.5V), and high-voltage X-ray detector bias supply (via PFI) in portable ultrasound units. IC Role / Device Role / Timing Role: Safety-critical supervisor asserting RST if any rail deviates, while PFO triggers immediate HV shutdown to prevent patient exposure risk. Use Value: Meets IEC 62304 Class C software safety requirements by providing hardware-enforced fail-safe response to power anomalies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6729KAUTD3-T | Push-pull PFO output instead of open-drain; identical VCC1/VCC2 thresholds, timeout, and pinout except PFO drive strength | Requires no external pullup on PFO; better suited for driving CMOS inputs directly without level-shifting | Select MAX6729KAUTD3-T when PFO must source current or interface directly to µP GPIO without pullup resistor |
| TPS3808G33DBVR | Dual-supply monitor only (no PFI/PFO); 3.3V fixed VDD threshold; 200ms timeout; SOT23-6 package | Lacks third-voltage monitoring and power-fail alerting; lower integration but smaller footprint and lower cost | Choose TPS3808G33DBVR for cost-sensitive dual-rail applications where PFI functionality is unnecessary |
Compared with MAX6728KALTD3-T, MAX6729KAUTD3-T offers enhanced PFO drive capability at identical supervision accuracy and timing, while TPS3808G33DBVR reduces BOM count and board area in simpler dual-supply designs - neither is pin-compatible, requiring layout revision.
Availability
MAX6728KALTD3-T is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and medical imaging subsystems requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to +85°C.
Supply support for MAX6728KALTD3-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 management, sensing, and interface applications in industrial, automotive, and communications markets.
The MAX6715–MAX6729 family delivers ultra-low-voltage, triple-supply supervision with integrated watchdog and power-fail detection - engineered specifically for reliability-critical multirail systems where simultaneous rail monitoring and deterministic reset behavior are mandatory.
FAQ
What is the exact reset threshold voltage for VCC1 on the MAX6728KALTD3-T?
The MAX6728KALTD3-T has a factory-trimmed VCC1 reset threshold of 4.625V (minimum 4.500V, maximum 4.750V) with ±0.5% hysteresis. This value is encoded in the "AL" suffix per Maxim's Reset Voltage Threshold Suffix Guide and is verified across –40°C to +85°C with 20ppm/°C tempco.
Does the MAX6728KALTD3-T support monitoring a negative supply voltage?
Yes - the MAX6728KALTD3-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, PFO asserts high (open-drain, pulled up externally), enabling detection of -5V, -12V, or other negative voltages down to –6V absolute rating.
What is the function of Pin 8 (NC) on the MAX6728KALTD3-T?
Pin 8 on the MAX6728KALTD3-T is a no-connect (NC) terminal - it is not bonded internally and must remain unconnected on the PCB. Routing traces or placing vias on this pad violates Maxim's layout guidelines and may compromise ESD immunity or thermal performance of the SOT23-8 package.
How does the watchdog timer behave after power-up on the MAX6728KALTD3-T?
Upon power-up or reset, the MAX6728KALTD3-T watchdog enters a 35s minimum startup period before transitioning to the 1.12s normal timeout mode. The first valid WDI edge (rising or falling) terminates the startup period early, allowing systems with fast boot sequences to engage tight watchdog supervision immediately.
Can the MAX6728KALTD3-T operate with VCC1 = 1.8V and VCC2 = 1.2V simultaneously?
Yes - the MAX6728KALTD3-T is fully specified to operate with VCC1 as low as 1.8V and VCC2 as low as 0.9V. At these levels, the device guarantees reset assertion integrity, 14µA supply current, and correct logic states on RST and PFO, making it suitable for modern ultra-low-voltage SoC power domains.
MAX6728KALTD3-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-8
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Power Supply Monitor
- Number of Voltages Monitored:
- 3
- Voltage - Threshold:
- 3.075V, 4.625V, Adj
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-8
MAX6728KALTD3-T FAQ
1.How can I place an order for MAX6728KALTD3-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6728KALTD3-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 MAX6728KALTD3-T reliable?
The price and inventory of MAX6728KALTD3-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6728KALTD3-T is usually 5 days.
3.What payment methods are accepted for MAX6728KALTD3-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6728KALTD3-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6728KALTD3-T?
MAX6728KALTD3-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6728KALTD3-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 MAX6728KALTD3-T?
For technical support, including MAX6728KALTD3-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6728KALTD3-T requirements.
6.How does Aetrix verify that MAX6728KALTD3-T is sourced from the original manufacturer or authorized distributors?
All MAX6728KALTD3-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 MAX6728KALTD3-T meets industry standards.
7.What is the process for return or replacement of MAX6728KALTD3-T?
All MAX6728KALTD3-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6728KALTD3-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 MAX6728KALTD3-T part is unused and in its original packaging.
Return procedure for MAX6728KALTD3-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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