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Analog Devices Inc./Maxim Integrated MAX6729KASHD3+
- Part No.:
- MAX6729KASHD3+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6729KASHD3+.pdf
- Description:
- IC SUPERVISOR 3 CHANNEL SOT23-8
- Quantity:
- Payment:
- Shipping:
Inventory:732
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Product details
Overview
MAX6729KASHD3+ 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 an auxiliary supply via RSTIN (626.5mV reference). It provides push-pull active-low reset output, power-fail input/output (PFI/PFO), manual reset input (MR), and watchdog timer with 35s startup / 1.12s normal timeout. Used in multivoltage telecom and industrial systems requiring reliable brownout detection and orderly shutdown.
For engineers reviewing the MAX6729KASHD3+ datasheet, MAX6729KASHD3+ pinout, MAX6729KASHD3+ application, or MAX6729KASHD3+ equivalent, key selection factors include its triple-supply monitoring capability, guaranteed reset validity down to VCC1/VCC2 = 0.8V, push-pull RST and PFO outputs referenced to VCC1, and factory-trimmed dual-threshold configuration with 210ms (min) reset timeout.
Technical Context
The MAX6729KASHD3+ integrates three independent voltage monitors: primary (VCC1), secondary (VCC2), and auxiliary (RSTIN), each with dedicated comparators and hysteresis. Its reset logic asserts RST low when any monitored voltage falls below its threshold and holds for a minimum 210ms after all voltages recover - a fixed timeout set by the 'D3' suffix.
This device implements a dual-mode watchdog timer: 35s minimum initial period after reset to accommodate system boot, followed by 1.12s minimum normal operation timeout triggered by WDI edge transitions. The PFI/PFO path operates independently of reset timing, deasserting PFO immediately upon PFI recovery without delay.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC1 Threshold | 4.625V (factory-trimmed, falling edge; ensures reliable reset assertion during 5V rail brownout) |
| VCC2 Threshold | 3.075V (factory-trimmed, falling edge; matches common 3.3V I/O supply tolerance) |
| RSTIN Reference | 626.5mV (internal bandgap reference; enables monitoring of supplies as low as 0.62V via resistor divider) |
| Reset Timeout | 210ms (minimum; guarantees µP reset hold time sufficient for full firmware initialization) |
| Supply Current | 14µA (typ at 3.6V; enables use in battery-backed or ultra-low-power standby modes) |
| Operating Temp | -40°C to +85°C (industrial grade; supports deployment in telecom equipment and embedded controllers) |
| Watchdog Period | 35s min startup / 1.12s min normal (dual-mode architecture prevents false resets during boot while ensuring rapid fault response in runtime) |
Pinout & Package
MAX6729KASHD3+ is housed in an 8-pin SOT23-8 package (3.0mm × 1.6mm × 1.1mm), optimized for space-constrained PCB layouts in portable and telecom equipment.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low push-pull reset output referenced to VCC1; drives high to ≥0.8×VCC1 when not asserted, low to ≤0.4V when asserted (ISINK = 3.2mA) |
| 2 | GND | System 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 required to trigger reset |
| 4 | PFO | Active-low push-pull power-fail output referenced to VCC1; asserts immediately when PFI < 626.5mV, deasserts with no timeout |
| 5 | VCC2 | Secondary supply input (0.9V–3.3V range); powers internal circuitry when > VCC1 and sets VCC2 monitor threshold |
| 6 | VCC1 | Primary supply input (1.8V–5.0V range); powers device when > VCC2 and sets VCC1 monitor threshold |
| 7 | PFI | Power-fail comparator noninverting input; high-impedance (±25nA) node for external resistor-divider monitoring of third supply |
| 8 | WDI | Watchdog input; rising/falling edge clears dual-mode timer; requires CMOS/TTL-compatible levels (VIH = 0.7×VCC1, VIL = 0.3×VCC1) |
Key Features
| Feature | Design Value |
|---|---|
| Triple-voltage supervision | Simultaneous monitoring of VCC1 (4.625V), VCC2 (3.075V), and auxiliary supply via PFI with 626.5mV reference |
| Push-pull RST and PFO outputs | No external pullup required; outputs actively drive high/low, simplifying interface to µP reset pins and interrupt lines |
| Dual-mode watchdog timer | 35s startup window accommodates full system boot; 1.12s runtime timeout ensures rapid processor hang detection |
| Guaranteed reset validity | Reset output remains logically valid even when VCC1 or VCC2 drops to 0.8V - critical for last-gasp shutdown sequencing |
| Immunity to VCC transients | Withstands negative-going glitches ≤20µs (at 100mV overdrive), preventing spurious resets in noisy power environments |
Applications
| Telecom Power Management | Industrial PLC Controller |
|---|---|
|
Use Scenario: Monitoring primary 48V DC-DC converter output (5V), isolated 3.3V I/O rail, and backup battery voltage in a cellular base station shelf controller. IC Role / Device Role / Timing Role: MAX6729KASHD3+ asserts RST to halt CPU execution and PFO to trigger battery-switchover logic before main rail collapse. Use Value: Prevents data corruption during brownout by enforcing 210ms reset hold and enabling controlled transition to backup power via PFI-triggered PFO. |
Use Scenario: Supervising 24V field bus supply, 5V logic rail, and 3.3V FPGA core voltage in an industrial programmable logic controller. IC Role / Device Role / Timing Role: MAX6729KASHD3+ uses MR for operator-initiated emergency stop and WDI to detect firmware lockup in safety-critical control loops. Use Value: Dual-mode watchdog ensures safe recovery from both boot failures (35s window) and runtime hangs (1.12s response), meeting SIL-2 functional safety requirements. |
| Network Switch ASIC Power Sequencing | Medical Diagnostic Equipment |
|
Use Scenario: Coordinating power-up sequence of multi-rail ASIC supply (1.2V core, 1.8V I/O, 3.3V analog) in a 10G Ethernet switch line card. IC Role / Device Role / Timing Role: MAX6729KASHD3+ monitors VCC1 (3.3V), VCC2 (1.8V), and RSTIN (1.2V via divider) to gate RST release only after all rails stabilize. Use Value: Factory-trimmed thresholds eliminate calibration overhead; 210ms timeout ensures ASIC internal state machines complete initialization before release. |
Use Scenario: Ensuring fail-safe shutdown of imaging subsystems (5V detector bias, 3.3V sensor interface, 1.8V ADC core) during AC mains interruption in MRI console. IC Role / Device Role / Timing Role: MAX6729KASHD3+ uses PFI to monitor battery-backed 3.3V rail and asserts PFO to initiate image save-to-flash before VCC1 collapse. Use Value: Immediate PFO assertion (no timeout) enables sub-millisecond warning to host processor, preserving diagnostic integrity during power loss. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6728KAHD3+ | Same pinout and thresholds, but open-drain PFO output instead of push-pull | Requires external pullup on PFO; unsuitable where active drive to µP interrupt pin is needed | Select MAX6728KAHD3+ only if PFO load requires open-drain compatibility or level-shifting |
| TPS3808G33DBVR | Dual-supply monitor (VDD, VDDIO) only; no PFI/PFO or WDI; 3.3V fixed VDD threshold; 200ms timeout | Lacks auxiliary voltage monitoring and power-fail signaling; no watchdog capability | Choose TPS3808G33DBVR for cost-sensitive dual-rail systems without PFI/WDT requirements |
Compared with MAX6729KASHD3+, MAX6728KAHD3+ offers identical supervision functionality but requires external pullup for PFO, while TPS3808G33DBVR reduces feature set to basic dual-rail monitoring - making MAX6729KASHD3+ the only option supporting simultaneous triple-supply monitoring, push-pull PFO, and dual-mode watchdog in SOT23-8.
Availability
MAX6729KASHD3+ is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, network switches, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX6729KASHD3+ 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 connectivity applications, with deep expertise in supervisory and power-management solutions.
The MAX6715–MAX6729 family delivers ultra-low-voltage, multi-rail supervision for space-constrained systems where reliability under brownout, transient immunity, and flexible reset timing are critical design requirements.
FAQ
What is the exact reset threshold voltage for VCC1 and VCC2 on the MAX6729KASHD3+?
The MAX6729KASHD3+ has factory-trimmed reset thresholds: VCC1 = 4.625V (±125mV) and VCC2 = 3.075V (±75mV), as defined by the 'SH' suffix per Maxim's Reset Voltage Threshold Suffix Guide. These values are guaranteed over -40°C to +85°C and ensure precise brownout detection for 5V and 3.3V rails without external calibration.
Does the MAX6729KASHD3+ support monitoring a third voltage below 1.0V?
Yes, the MAX6729KASHD3+ supports monitoring auxiliary supplies as low as 0.62V using the PFI input and its internal 626.5mV reference. By connecting an external resistor divider between the target supply and GND, with PFI at the divider midpoint, the device triggers PFO when the supply falls below the calculated trip point - enabling sub-1V rail supervision.
How does the watchdog timer behave after power-on versus during normal operation for the MAX6729KASHD3+?
The MAX6729KASHD3+ implements a dual-mode watchdog: after any reset event (power-up, MR, or timeout), it enters a 35s minimum startup mode to allow full system boot; once WDI receives its first valid edge, it switches to 1.12s minimum normal mode. This prevents false timeouts during initialization while ensuring rapid fault detection during runtime.
Can the MAX6729KASHD3+ generate a reset if only VCC2 drops out while VCC1 remains valid?
Yes, the MAX6729KASHD3+ asserts RST whenever either VCC1 or VCC2 falls below its respective threshold - independent of the other rail's status. Since VCC2 threshold is 3.075V, a drop below that level (e.g., 3.0V) will trigger reset even if VCC1 remains at 4.6V, ensuring protection for secondary supply-dependent peripherals.
What is the maximum load current the MAX6729KASHD3+ RST output can sink in push-pull mode?
The MAX6729KASHD3+ RST output can sink up to 3.2mA while maintaining VOL ≤ 0.4V (at VCC1 ≥ 4.5V), per its Electrical Characteristics table. This drive strength supports direct connection to most µP reset inputs without series resistance, and exceeds typical MCU reset pin leakage requirements by >10×.
MAX6729KASHD3+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-8
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Multi-Voltage Supervisor
- Number of Voltages Monitored:
- 3
- Voltage - Threshold:
- 1.313V, 2.925V, Adj
- Output:
- Push-Pull, Totem Pole
- 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
MAX6729KASHD3+ FAQ
1.How can I place an order for MAX6729KASHD3+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6729KASHD3+ 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 MAX6729KASHD3+ reliable?
The price and inventory of MAX6729KASHD3+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6729KASHD3+ is usually 5 days.
3.What payment methods are accepted for MAX6729KASHD3+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6729KASHD3+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6729KASHD3+?
MAX6729KASHD3+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6729KASHD3+ 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 MAX6729KASHD3+?
For technical support, including MAX6729KASHD3+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6729KASHD3+ requirements.
6.How does Aetrix verify that MAX6729KASHD3+ is sourced from the original manufacturer or authorized distributors?
All MAX6729KASHD3+ 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 MAX6729KASHD3+ meets industry standards.
7.What is the process for return or replacement of MAX6729KASHD3+?
All MAX6729KASHD3+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6729KASHD3+, 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 MAX6729KASHD3+ part is unused and in its original packaging.
Return procedure for MAX6729KASHD3+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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