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Analog Devices Inc./Maxim Integrated MAX6391KA26-T
- Part No.:
- MAX6391KA26-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6391KA26-T.pdf
- Description:
- IC SUPERVISOR 2 CHANNEL SOT23-8
- Quantity:
- Payment:
- Shipping:
Inventory:10,000
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Product details
Overview
MAX6391KA26-T from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced active-low open-drain reset outputs, factory-set VCC reset threshold of 2.63V, 140ms minimum RESET1 timeout, and adjustable RESET2 timeout via CSRT pin. It monitors master (VCC) and slave (RESET IN2) supplies in multi-rail systems to enforce power-up sequencing between primary and secondary processors or peripherals.
For engineers reviewing the MAX6391KA26-T datasheet, MAX6391KA26-T pinout, MAX6391KA26-T application, or MAX6391KA26-T equivalent, key selection criteria include guaranteed reset validity down to VCC = 1V, internal 47kΩ pullup resistors on both RESET outputs, immunity to short negative VCC transients, and support for dual-supply monitoring with independent timing control.
Technical Context
The MAX6391KA26-T implements two independent voltage comparators: one fixed-threshold (2.63V) comparator for VCC monitoring driving RESET1, and a second 625mV reference comparator for RESET IN2 driving RESET2. RESET1 deasserts 140ms (min) after VCC exceeds 2.63V; RESET2 deasserts either 140ms (min) after both VCC and RESET IN2 exceed thresholds (CSRT tied to VCC), or after a capacitor-adjustable delay (CSRT to ground).
RESET2 always asserts before RESET1 during power-down and deasserts after RESET1 during power-up, enforcing strict sequencing. The device uses BiCMOS process (810 transistors), operates from 1.2V to 5.5V supply, draws 15µA typical supply current, and guarantees functional reset behavior down to VCC = 1.0V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Reset Threshold | 2.63V (factory-fixed; ensures reliable reset assertion when main supply drops below nominal 2.7V rail) |
| RESET IN2 Threshold | 625mV (fixed internal reference; enables monitoring of secondary supplies as low as 0.625V via external resistor divider) |
| RESET1 Timeout | 140ms min (internally fixed; provides stable, temperature-compensated reset hold time for primary processor) |
| RESET2 Timeout | 140ms min (fixed mode) or user-adjustable (capacitor mode); enables flexible sequencing delay for secondary subsystems |
| Supply Current | 15µA typical (ultra-low quiescent current; minimizes impact on battery-backed or low-power systems) |
| Reset Validity Range | VCC ≥ 1.0V (guaranteed operation down to brownout levels; supports robust reset during deep undervoltage conditions) |
| Output Type | Open-drain RESET1 & RESET2 (allows level-shifting to external VOH voltages via internal 47kΩ pullups R1/R2) |
Pinout & Package
MAX6391KA26-T is housed in an 8-pin SOT23-8 package (3.00mm × 1.75mm × 1.30mm body, 0.65mm pitch), specified for -40°C to +85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - RESET IN2 | Secondary supply monitor input | High-impedance node for external resistor divider; sets RESET2 activation threshold for slave rails (e.g., 1.2V, 1.8V) |
| 2 - VCC | Main supply input & power rail | Primary monitored voltage (2.63V threshold) and device power source; asserts all resets when falling |
| 3 - CSRT | RESET2 timeout configuration | Connect to VCC for fixed 140ms delay; connect to capacitor for user-defined delay (e.g., 3.1ms with 1500pF) |
| 4 - GND | Ground reference | Analog/digital common return; required for comparator reference stability and output sink paths |
| 5 - RESET2 | Secondary reset output | Active-low open-drain output; asserts before RESET1 on power-down, deasserts after RESET1 on power-up |
| 6 - R2 | Internal pullup connection for RESET2 | 47kΩ resistor tied internally to RESET2; connect to external VOH (e.g., 3.3V) for level-shifted high-state drive |
| 7 - RESET1 | Primary reset output | Active-low open-drain output; controls master processor reset with fixed 140ms hold time |
| 8 - R1 | Internal pullup connection for RESET1 | 47kΩ resistor tied internally to RESET1; enables independent VOH setting without external components |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent voltage monitoring | Simultaneous VCC (2.63V) and RESET IN2 (625mV ref) supervision enables true multi-rail sequencing without external comparators |
| Guaranteed reset operation at low VCC | Functional down to VCC = 1.0V ensures valid reset signaling even during severe brownout conditions |
| Internal pullup resistors | 47kΩ R1/R2 eliminate need for external pullups and allow RESET outputs to interface with higher VOH rails (e.g., 3.3V/5V) |
| Transient immunity | Immunity to short negative VCC glitches (<100ns at 100mV overdrive) prevents spurious resets in noisy power environments |
| Low quiescent current | 15µA typical ICC enables use in always-on monitoring circuits without significant battery drain |
Applications
| Industrial PLC Power Sequencing | Multi-Rail FPGA Configuration |
|---|---|
Use Scenario: Programmable logic controller with separate 2.5V I/O and 1.2V core supplies requiring controlled power-up order. IC Role / Device Role / Timing Role: MAX6391KA26-T acts as dual-supply supervisor, asserting RESET2 on 1.2V rail first, then RESET1 on 2.5V rail after 140ms delay to ensure core logic initializes before I/O. Use Value: Eliminates risk of latch-up or undefined state by enforcing strict voltage sequencing per FPGA vendor requirements. | Use Scenario: FPGA-based embedded vision system using 3.3V peripheral interface and 1.8V processing core. IC Role / Device Role / Timing Role: MAX6391KA26-T monitors 3.3V VCC (2.63V threshold) for RESET1 and 1.8V rail via RESET IN2 divider for RESET2, ensuring peripherals are ready before core boot. Use Value: Prevents configuration failure by guaranteeing 1.8V rail stabilizes and holds reset for defined period before releasing FPGA core. |
| Server Board Dual-Voltage Monitoring | Medical Imaging Sensor Module |
Use Scenario: Rack-mount server motherboard with 12V-to-3.3V and 12V-to-1.0V DC/DC converters powering CPU and memory subsystems. IC Role / Device Role / Timing Role: MAX6391KA26-T uses VCC = 3.3V (2.63V threshold) for RESET1 and 1.0V rail via RESET IN2 divider for RESET2, coordinating reset release across voltage domains. Use Value: Ensures memory controller resets only after CPU voltage is stable, preventing bus contention and data corruption during boot. | Use Scenario: Portable ultrasound sensor module with battery-backed 3.3V analog front-end and 1.2V digital signal processor. IC Role / Device Role / Timing Role: MAX6391KA26-T monitors main 3.3V rail (2.63V threshold) for RESET1 and 1.2V DSP supply (via divider on RESET IN2) for RESET2, enabling safe power-down sequencing. Use Value: Guarantees DSP completes shutdown sequence before analog section powers off, preserving calibration integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6392KA26-T | Includes active-low manual reset (MR) input and push-pull RESET1; lacks R1 pullup resistor | Required where hardware-initiated reset (e.g., front-panel button) is needed; not drop-in compatible due to MR pin and output type change | Select MAX6392KA26-T only if manual reset functionality is mandatory and PCB layout accommodates MR routing and push-pull drive |
| TPS3808G33DBVR | Single-supply supervisor (3.3V threshold only); no secondary monitor input or sequenced outputs | Suitable for single-rail systems only; cannot replace dual-monitoring or sequencing function of MAX6391KA26-T | Use TPS3808G33DBVR only for cost-sensitive, single-voltage applications where RESET2 sequencing is unnecessary |
Compared with MAX6392KA26-T, the MAX6391KA26-T offers simpler open-drain outputs with internal pullups but no manual reset; compared with TPS3808G33DBVR, it provides unique dual-supply monitoring and enforced power-up/down sequencing essential for multi-rail reliability.
Availability
MAX6391KA26-T is available at Aetrix Electronics and suitable for industrial PLCs, FPGA configuration boards, server motherboards, and medical sensor modules requiring stable component supply with guaranteed long-term availability.
Supply support for MAX6391KA26-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, computing, and communications applications.
The MAX6391/MAX6392 product line delivers dual-voltage microprocessor supervisory circuits with sequenced reset outputs, targeting systems requiring reliable power-up/down coordination across multiple supply rails.
FAQ
What is the factory-set VCC reset threshold voltage for MAX6391KA26-T?
The MAX6391KA26-T has a factory-set VCC reset threshold of 2.63V (minimum 2.55V, maximum 2.70V across temperature). This value is laser-trimmed during production and applies specifically to the KA26 variant, enabling precise supervision of 2.7V nominal rails. The threshold is fixed and non-adjustable; other variants (e.g., KA46 = 4.63V) require different part numbers. MAX6391KA26-T guarantees reset assertion whenever VCC falls below this threshold and maintains reset for at least 140ms after recovery.
How does the CSRT pin configure RESET2 timeout behavior on MAX6391KA26-T?
The CSRT pin on MAX6391KA26-T determines RESET2 timeout mode: connecting CSRT to VCC selects a fixed 140ms (minimum) delay, while connecting CSRT to an external capacitor (to ground) enables user-adjustable timing based on C × ΔV/I (ΔV = 1.25V, I = 600nA). For example, a 1500pF capacitor yields ~3.1ms delay. The MAX6391KA26-T internally detects the CSRT connection state and configures its timing circuitry accordingly-no external logic or configuration registers are involved. This dual-mode flexibility supports both simple fixed-delay and precision-timed sequencing needs.
Does MAX6391KA26-T support monitoring of supply voltages lower than 1.0V?
No, MAX6391KA26-T does not support direct monitoring of supply voltages below 1.0V. Its RESET IN2 input uses a fixed 625mV internal reference, but the minimum valid input voltage for reliable comparator operation is constrained by the device's VCC operating range (1.2V to 5.5V) and specification that reset functionality is guaranteed only down to VCC = 1.0V. While the 625mV reference allows setting thresholds for secondary supplies as low as ~0.625V using an external resistor divider (e.g., monitoring a 1.2V rail at 0.9V), the monitored rail itself must be ≥1.2V to power the IC. Voltages below 1.0V cannot be reliably supervised by MAX6391KA26-T.
Can MAX6391KA26-T be used in systems with 3.3V and 1.8V rails?
Yes, MAX6391KA26-T is explicitly designed for such dual-rail systems. Configure VCC = 3.3V (within 1.2V–5.5V range) to trigger RESET1 at 2.63V, and use an external resistor divider on RESET IN2 to scale the 1.8V rail down to 625mV (e.g., R3 = 1.4MΩ, R4 = 500kΩ). This ensures RESET2 asserts when the 1.8V rail drops below ~1.5V. The device enforces sequencing: RESET2 deasserts after RESET1 during power-up, preventing the 1.8V domain from initializing before the 3.3V domain is stable. MAX6391KA26-T's guaranteed operation down to VCC = 1.0V further enhances robustness during brownout transitions between these rails.
What is the purpose of the R1 and R2 pins on MAX6391KA26-T?
The R1 and R2 pins on MAX6391KA26-T provide dedicated connections to internal 47kΩ pullup resistors tied to RESET1 and RESET2 outputs, respectively. Unlike standard open-drain supervisors requiring external pullups, these pins let designers connect R1/R2 directly to any desired VOH voltage (e.g., 3.3V, 5V, or 1.8V) to set the high-state level of each reset signal independently. This eliminates external components, supports mixed-voltage system interfacing, and ensures clean logic-level compatibility with diverse downstream devices-all while maintaining the open-drain flexibility of MAX6391KA26-T's reset outputs.
MAX6391KA26-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:
- Multi-Voltage Supervisor
- Number of Voltages Monitored:
- 2
- Voltage - Threshold:
- 2.63V, Adj
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- 140ms/Adjustable Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-8
MAX6391KA26-T FAQ
1.How can I place an order for MAX6391KA26-T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6391KA26-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 MAX6391KA26-T reliable?
The price and inventory of MAX6391KA26-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6391KA26-T is usually 5 days.
3.What payment methods are accepted for MAX6391KA26-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6391KA26-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6391KA26-T?
MAX6391KA26-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6391KA26-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 MAX6391KA26-T?
For technical support, including MAX6391KA26-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6391KA26-T requirements.
6.How does Aetrix verify that MAX6391KA26-T is sourced from the original manufacturer or authorized distributors?
All MAX6391KA26-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 MAX6391KA26-T meets industry standards.
7.What is the process for return or replacement of MAX6391KA26-T?
All MAX6391KA26-T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6391KA26-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 MAX6391KA26-T part is unused and in its original packaging.
Return procedure for MAX6391KA26-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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