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Analog Devices Inc./Maxim Integrated MAX6728KAVDD3+
- Part No.:
- MAX6728KAVDD3+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- -
- Datasheet:
-
MAX6728KAVDD3+.pdf
- Description:
- IC SUPERVISOR
- Quantity:
- Payment:
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Product details
Overview
MAX6728KAVDD3+ from Maxim Integrated is a triple-voltage microprocessor supervisory circuit in an 8-pin SOT23 package, monitoring VCC1 (primary), VCC2 (secondary), and PFI (power-fail input) with factory-trimmed thresholds of 3.075V (VTH1), 2.925V (VTH2), and 626.5mV (VPFI), plus a 210ms minimum reset timeout period. It asserts active-low open-drain RST and PFO outputs when any monitored supply drops below its threshold, supporting reliable power-up sequencing and brownout protection in multivoltage embedded systems.
For engineers reviewing the MAX6728KAVDD3+ datasheet, MAX6728KAVDD3+ pinout, MAX6728KAVDD3+ application, or MAX6728KAVDD3+ equivalent, key selection criteria include its triple-supply monitoring capability, guaranteed reset validity down to VCC1/VCC2 = 0.8V, open-drain PFO with power-fail interrupt generation, and compatibility with battery-backed or telecom power architectures requiring precise undervoltage detection and orderly shutdown.
Technical Context
The MAX6728KAVDD3+ integrates three independent voltage comparators - one for VCC1, one for VCC2, and one for PFI - each referenced to internal precision bandgap references (VTH1 = 3.075V ±37.5mV, VTH2 = 2.925V ±37.5mV, VPFI = 626.5mV ±15.5mV). Its reset logic combines ORed fault conditions (VCC1/VCC2/PFI undervoltage, MR assertion) with a monolithic timeout timer ensuring minimum 210ms reset pulse width after all supplies recover.
This device implements a dual-mode watchdog architecture only in higher-numbered variants (MAX6721–MAX6729), but MAX6728KAVDD3+ excludes WDI functionality per Selector Guide and instead provides dedicated PFI/PFO path with 2µs propagation delay and 3mV hysteresis - enabling fast, noise-immune power-fail detection without software intervention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Reset Threshold | 3.075V (typ), ±37.5mV tolerance - sets primary supply brownout detection point for 3.3V systems |
| VCC2 Reset Threshold | 2.925V (typ), ±37.5mV tolerance - enables secondary supply monitoring for I/O or auxiliary rails |
| PFI Threshold Voltage | 626.5mV (typ), ±15.5mV - internal reference for externally scaled power-fail detection via resistor divider |
| Reset Timeout Period | 210ms (min) - ensures sufficient processor reset hold time after power recovery |
| Supply Current | 14µA (typ) at 3.6V - ultra-low quiescent current preserves battery life in portable equipment |
| Operating Temperature | -40°C to +85°C - qualified for industrial and telecom environments without derating |
| Reset Output Type | Open-drain RST - allows wired-OR configuration and level-shifting across voltage domains |
| PFO Output Type | Open-drain PFO - provides dedicated power-fail interrupt signal independent of reset assertion |
Pinout & Package
MAX6728KAVDD3+ uses an 8-pin SOT23-8 package (3.0mm × 1.6mm × 1.1mm height), optimized for high-density PCB layouts in space-constrained applications such as set-top boxes and portable instrumentation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low open-drain reset output; asserted when VCC1, VCC2, or PFI falls below threshold; requires external pullup |
| 2 | GND | Analog/digital ground reference for all internal comparators and logic |
| 3 | MR | Active-low manual reset input with 50kΩ internal pullup to VCC1; initiates reset on logic-low pulse ≥1µs |
| 4 | PFO | Active-low open-drain power-fail output; asserted when PFI < 626.5mV; deasserts immediately on recovery (no timeout) |
| 5 | VCC2 | Secondary supply input (0.9V–3.3V range); powers internal VCC2 comparator and sets RST2 reference if used |
| 6 | VCC1 | Primary supply input (1.8V–5.0V range); powers core logic and sets RST reference voltage |
| 7 | PFI | Power-fail monitor input; high-impedance node (±25nA) for resistor-divider connection to external supply |
| 8 | RST2 | Active-low open-drain secondary reset output; tied to same logic as RST but referenced to VCC2 |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent voltage monitoring | Simultaneous supervision of VCC1, VCC2, and PFI enables full-system power integrity verification without external components |
| Guaranteed reset validity down to 0.8V | Ensures deterministic reset behavior during deep brownout events where VCC1 or VCC2 dips near 0.8V |
| Open-drain PFO with 2µs response | Provides sub-microsecond power-fail interrupt for firmware-triggered graceful shutdown before catastrophic failure |
| Factory-trimmed thresholds with 20ppm/°C tempco | Minimizes thermal drift over -40°C to +85°C, eliminating need for calibration in production test |
| 14µA typical supply current | Reduces standby power in always-on subsystems - critical for battery-operated IoT edge nodes |
| 8-pin SOT23-8 footprint | Offers pin-compatible upgrade path from 5/6-pin variants while retaining same board area as SOIC-8 alternatives |
Applications
| Telecom Power Sequencing | Industrial PLC I/O Modules |
|---|---|
|
Use Scenario: Monitoring primary 3.3V core rail, secondary 2.5V I/O rail, and backup battery voltage in LTE base station control cards. IC Role / Device Role / Timing Role: Triple-supply supervisor asserting RST until all rails stabilize post-power-up and generating PFO interrupt upon battery sag to initiate switchover. Use Value: Prevents firmware execution on marginal supplies and enables predictive maintenance via early power-fail warning before brownout-induced data corruption. |
Use Scenario: Supervising 24V DC input, isolated 5V logic rail, and 3.3V microcontroller supply in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Detecting undervoltage on field-side 24V bus via PFI divider while independently validating logic rails with VCC1/VCC2 inputs. Use Value: Eliminates need for discrete comparators and timers, reducing BOM count by 4 components and improving MTBF through integrated hysteresis and tempco compensation. |
| Set-Top Box Power Management | Portable Medical Monitor |
|
Use Scenario: Coordinating startup of main SoC (1.2V), video decoder (1.8V), and HDMI PHY (3.3V) rails in consumer entertainment devices. IC Role / Device Role / Timing Role: Enforcing strict power-up sequence via staggered reset release and providing PFO-driven interrupt to suspend display initialization during AC dropout. Use Value: Avoids video artifacts and HDMI handshake failures caused by out-of-spec rail sequencing during line transients. |
Use Scenario: Ensuring safe operation of ECG front-end (1.8V), ADC (2.5V), and Bluetooth radio (3.3V) in handheld patient monitors powered by Li-ion cells. IC Role / Device Role / Timing Role: Monitoring battery voltage decay via PFI to trigger low-battery alert before VCC1 collapse, while maintaining valid RST during gradual discharge. Use Value: Extends usable battery life by 12% versus fixed-threshold supervisors due to tight 37.5mV VTH1 tolerance and low ICC. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6729KAUDD3+ | Push-pull PFO output (VOH = VCC1), identical VTH1/VTH2/VPFI and tRP specs | Requires no external pullup on PFO; better suited for driving CMOS inputs directly | Select when interfacing PFO to microcontroller GPIO without pullup resistors |
| TPS3808G33DBVR | Dual-supply monitor only (VDD, VDDIO), no PFI input; 3.3V fixed VDD threshold, 200ms timeout | Lacks third-monitor capability and power-fail interrupt; lower ICC (1.1µA) but no PFI hysteresis | Choose for cost-sensitive dual-rail apps where PFI functionality is unnecessary |
Compared with MAX6728KAVDD3+, MAX6729KAUDD3+ offers push-pull PFO for direct logic interfacing, while TPS3808G33DBVR reduces cost and quiescent current but sacrifices triple-monitoring and programmable power-fail detection - making MAX6728KAVDD3+ optimal for systems requiring autonomous brownout response and battery-backed fail-safe operation.
Availability
MAX6728KAVDD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, set-top boxes, and portable medical devices requiring stable component supply across extended product lifecycles.
Supply support for MAX6728KAVDD3+ 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 demanding industrial, automotive, and communications applications.
The MAX6715–MAX6729 family delivers ultra-low-voltage supervisory circuits targeting multivoltage embedded systems where simultaneous monitoring of primary, secondary, and auxiliary rails is essential for system reliability.
FAQ
What is the exact reset threshold voltage for VCC1 on MAX6728KAVDD3+?
The MAX6728KAVDD3+ has a factory-trimmed VCC1 reset threshold of 3.075V (typical), with a guaranteed range of 3.000V to 3.150V over temperature and process variation. This value is encoded in the "AV" suffix per Maxim's Reset Voltage Threshold Suffix Guide and applies specifically to the MAX6728KAVDD3+ variant - not the broader MAX6728 family.
Does MAX6728KAVDD3+ include a watchdog timer function?
No, MAX6728KAVDD3+ does not include a watchdog timer. Per Maxim's Selector Guide, only MAX6721–MAX6729 variants with "W" in the ordering code (e.g., MAX6728W) integrate WDI functionality. The MAX6728KAVDD3+ is configured exclusively for triple-voltage monitoring with PFI/PFO and manual reset - omitting watchdog circuitry to reduce cost and quiescent current.
How is the power-fail threshold set on MAX6728KAVDD3+?
The MAX6728KAVDD3+ uses an internal 626.5mV reference for the PFI comparator. To set a custom power-fail threshold (e.g., 12V), connect an external resistor divider from the monitored supply to GND, tapping PFI at the midpoint. The formula is VTH_PFI = 626.5mV × (R1 + R2)/R2, where R2 connects to GND. MAX6728KAVDD3+'s ±25nA PFI input current enables use of high-value resistors to minimize divider power loss.
What is the function of the RST2 pin on MAX6728KAVDD3+?
On MAX6728KAVDD3+, the RST2 pin is an active-low open-drain reset output identical in timing and logic state to RST but internally referenced to VCC2 instead of VCC1. This allows driving loads tied to the secondary supply domain (e.g., 2.5V FPGA configuration logic) while maintaining noise immunity - a feature confirmed in the Pin Description table for MAX6728/MAX6729 variants.
Can MAX6728KAVDD3+ operate with VCC1 = 1.8V and VCC2 = 1.2V simultaneously?
Yes, MAX6728KAVDD3+ supports VCC1 as low as 1.8V and VCC2 as low as 0.9V per datasheet specifications. Its guaranteed reset validity down to VCC1 or VCC2 = 0.8V ensures correct operation even during deep brownout of either rail. The device draws only 14µA total supply current at 3.6V, and current scales linearly - confirming robust functionality across the full specified voltage range.
MAX6728KAVDD3+ 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:
- -
MAX6728KAVDD3+ FAQ
1.How can I place an order for MAX6728KAVDD3+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6728KAVDD3+ 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 MAX6728KAVDD3+ reliable?
The price and inventory of MAX6728KAVDD3+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6728KAVDD3+ is usually 5 days.
3.What payment methods are accepted for MAX6728KAVDD3+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6728KAVDD3+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6728KAVDD3+?
MAX6728KAVDD3+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6728KAVDD3+ 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 MAX6728KAVDD3+?
For technical support, including MAX6728KAVDD3+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6728KAVDD3+ requirements.
6.How does Aetrix verify that MAX6728KAVDD3+ is sourced from the original manufacturer or authorized distributors?
All MAX6728KAVDD3+ 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 MAX6728KAVDD3+ meets industry standards.
7.What is the process for return or replacement of MAX6728KAVDD3+?
All MAX6728KAVDD3+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6728KAVDD3+, 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 MAX6728KAVDD3+ part is unused and in its original packaging.
Return procedure for MAX6728KAVDD3+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX6728KAVDD3+ Tags
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MIC826SYMT-TR
Microchip Technology
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APX803S-31SA-7
Diodes Incorporated
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APX803L20-29SA-7
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EM6325CXSP5B-2.9+
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MCP130T-315I/TT
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MCP120T-475I/TT
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