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Analog Devices Inc./Maxim Integrated MAX6391KA44+
- Part No.:
- MAX6391KA44+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6391KA44+.pdf
- Description:
- IC SUPERVISOR 2 CHANNEL SOT23-8
- Quantity:
- Payment:
- Shipping:
Inventory:1,291
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Product details
Overview
MAX6391KA44+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced open-drain reset outputs, monitoring VCC (4.38V factory-fixed threshold) and adjustable RESET IN2 (625mV reference), delivering guaranteed reset validity down to VCC = 1V and 140ms minimum timeout for RESET1. It enables controlled power-up sequencing in multi-rail systems such as industrial controllers and set-top boxes.
For engineers reviewing the MAX6391KA44+ datasheet, MAX6391KA44+ pinout, MAX6391KA44+ application, or MAX6391KA44+ equivalent, key selection criteria include its dual-supply monitoring capability, fixed 4.38V VCC threshold, internal 47kΩ pullup resistors on both RESET outputs, SOT23-8 package footprint, and immunity to short negative VCC transients.
Technical Context
The MAX6391KA44+ implements two independent voltage comparators: one for VCC (with factory-trimmed 4.38V threshold) and one for RESET IN2 (referenced to 625mV). RESET1 asserts only on VCC undervoltage and deasserts after a fixed 140ms (min) timeout; RESET2 asserts if either VCC or RESET IN2 falls below their thresholds and deasserts after 140ms (min) or a capacitor-adjustable period via CSRT.
RESET2 always deasserts after RESET1 during power-up and asserts before RESET1 during power-down - enforcing strict sequencing. The device operates from 1.2V to 5.5V, draws 15µA typical supply current, and guarantees functional reset behavior down to VCC = 1.0V, supporting low-voltage system designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Reset Threshold | 4.38V (factory-trimmed, ±13mV max deviation; sets primary brownout detection point) |
| RESET IN2 Threshold | 625mV (internal reference; enables monitoring of secondary supplies as low as ~625mV via external divider) |
| RESET1 Timeout | 140ms min (fixed internal timer; ensures µP remains held in reset long enough for stable VCC recovery) |
| RESET2 Timeout | 140ms min (fixed when CSRT tied to VCC) or user-adjustable (via external capacitor on CSRT pin) |
| Supply Current | 15µA typical (enables use in battery-backed or ultra-low-power systems without significant load) |
| Operating Voltage Range | 1.2V to 5.5V (supports wide input range including 1.8V, 2.5V, 3.3V, and 5V rails) |
| Reset Validity Limit | VCC ≥ 1.0V (guarantees correct reset assertion even during deep brownout conditions) |
Pinout & Package
MAX6391KA44+ is housed in an 8-pin SOT23 package (JEDEC MO-178 compliant, 1.95mm × 2.80mm × 1.45mm body), optimized for space-constrained PCB layouts and compatible with standard high-volume SMT assembly processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - RESET IN2 | Secondary supply monitor input | High-impedance comparator input referenced to 625mV; accepts external resistive divider to set custom reset threshold for slave rail |
| 2 - VCC | Main supply and master reset source | Power supply input and primary voltage monitor; all resets assert when VCC drops below 4.38V |
| 3 - CSRT | RESET2 timeout configuration node | Connect to VCC for fixed 140ms RESET2 delay; connect to external capacitor for user-adjustable timeout (e.g., 3.1ms with 1500pF) |
| 4 - GND | Analog/digital ground reference | Common return path for all internal comparators, timers, and output drivers |
| 5 - RESET2 | Secondary active-low open-drain reset | Drives low when VCC or RESET IN2 fails; requires external pullup; deasserts after RESET1 during power-up |
| 6 - R2 | Internal pullup connection for RESET2 | 47kΩ resistor internally connected to RESET2; tie to desired VOH voltage (e.g., 3.3V or 5V) for level-shifted reset signaling |
| 7 - RESET1 | Primary active-low open-drain reset | Drives low on VCC undervoltage only; deasserts first during power-up; timing fully internal and fixed |
| 8 - R1 | Internal pullup connection for RESET1 | 47kΩ resistor internally connected to RESET1; allows independent VOH setting without external components |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent voltage monitoring | Enables simultaneous supervision of master (VCC) and slave (RESET IN2) rails with distinct thresholds and timing |
| Factory-trimmed VCC threshold (4.38V) | Eliminates external resistor network for primary reset; improves accuracy and reduces BOM count |
| Internal 47kΩ pullup resistors on both RESET outputs | Supports flexible VOH levels (e.g., 3.3V logic driving 5V µP) without discrete pullups or layout changes |
| Guaranteed reset operation down to VCC = 1.0V | Ensures reliable reset assertion during severe brownout, extending system robustness beyond typical 1.2V limits |
| Immunity to short negative VCC transients | Rejects glitches ≤100ns at 50mV overdrive, preventing spurious resets in noisy power environments |
Applications
| Industrial PLC Controllers | Set-Top Box Power Sequencing |
|---|---|
Use Scenario: Multi-rail power management in programmable logic controllers where 24V, 5V, and 3.3V rails must power up/down in strict order to prevent latch-up or I/O contention. IC Role / Device Role / Timing Role: Primary supervisory IC enforcing RESET1 → RESET2 sequence: RESET1 holds main CPU until 5V stabilizes; RESET2 then releases FPGA or interface IC after 140ms delay. Use Value: Eliminates need for discrete RC timers and dual comparators, reducing board area by >40% and improving timing repeatability across temperature (-40°C to +85°C). | Use Scenario: Dual-supply monitoring in consumer STB platforms with separate 12V analog tuner, 3.3V SoC, and 1.8V memory rails. IC Role / Device Role / Timing Role: Monitors 3.3V VCC (4.38V threshold unused; configured for 3.3V via external divider on RESET IN2) and 1.8V rail via resistive divider on RESET IN2. Use Value: Enables single-chip sequencing where RESET1 releases SoC first, then RESET2 releases DDR controller only after SoC is fully operational - preventing initialization race conditions. |
| Network Printer Mainboard | Medical Diagnostic Sensor Hub |
Use Scenario: Power integrity assurance in laser printer mainboards with high-current motor drivers, ASICs, and flash memory subsystems. IC Role / Device Role / Timing Role: Uses VCC = 5V rail as master; RESET IN2 monitors 3.3V logic rail. RESET1 holds MCU during 5V ramp; RESET2 delays release of motor driver enable until logic is stable. Use Value: Prevents motor driver activation before control firmware loads, avoiding mechanical fault conditions and enabling fail-safe shutdown on brownout. | Use Scenario: Battery-powered portable diagnostic sensor hub requiring ultra-low quiescent current and brownout resilience during intermittent Li-ion discharge. IC Role / Device Role / Timing Role: Supervises 3.3V main rail (VCC) and 1.8V sensor interface rail (RESET IN2); leverages 15µA ICC and 1.0V reset validity to extend usable battery window. Use Value: Guarantees clean reset assertion even as battery sags to 3.0V under load, ensuring sensor data integrity and eliminating corrupted boot sequences. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6392KA44+ | Includes active-low manual reset (MR) input and push-pull RESET1; lacks R1 pullup resistor | Required where field-service reset or software-triggered reinitialization is needed | Select MAX6392KA44+ only if MR functionality is mandatory; otherwise MAX6391KA44+ offers simpler design with dual pullups |
| TPS3808G33DBVR | Single-supply supervisor (3.3V fixed threshold); no secondary supply monitor or sequenced outputs | Suitable only for single-rail systems; cannot replace dual-monitoring or sequencing requirement | Use only for cost-sensitive, single-rail applications lacking sequencing needs; not a functional substitute for MAX6391KA44+ |
Compared with MAX6392KA44+, the MAX6391KA44+ provides dedicated internal pullups for both RESET outputs but omits manual reset - making it optimal for fixed-configuration embedded systems. Compared with TPS3808G33DBVR, it adds critical dual-rail monitoring and enforced reset ordering, essential for multi-voltage SoC platforms.
Availability
MAX6391KA44+ is available at Aetrix Electronics and suitable for industrial controllers, set-top boxes, and medical sensor hubs requiring stable component supply, extended temperature operation (-40°C to +85°C), and RoHS-compliant lead-free packaging.
Supply support for MAX6391KA44+ 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) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and computing markets.
The MAX6391/MAX6392 product line was designed specifically for reliable power sequencing in dual-voltage microprocessor systems, addressing the need for deterministic reset ordering without external timing components.
FAQ
What is the factory-set VCC reset threshold voltage for MAX6391KA44+?
The MAX6391KA44+ has a factory-trimmed VCC reset threshold of 4.38V, with a maximum tolerance of ±13mV. This value is laser-trimmed during production and is specific to the KA44 suffix. It defines the precise voltage at which RESET1 asserts during VCC brownout, and is confirmed in the Electrical Characteristics table under "VCC Reset Threshold" for part number MAX6391KA44+.
Does MAX6391KA44+ support adjustable RESET2 timeout, and how is it implemented?
Yes, MAX6391KA44+ supports user-adjustable RESET2 timeout via the CSRT pin. Connecting an external capacitor from CSRT to ground enables timing based on a 600nA internal current source and 1.25V reference: tRP2 ≈ 2.08 × 10⁶ × CCSRT. For example, a 1500pF capacitor yields ~3.1ms. Alternatively, tying CSRT to VCC selects a fixed 140ms (min) timeout. This flexibility is documented in the Applications Information section and Electrical Characteristics table for MAX6391KA44+.
Can MAX6391KA44+ monitor a 1.8V supply as the secondary rail, and what external components are required?
Yes, MAX6391KA44+ can monitor a 1.8V supply on RESET IN2 using an external resistive divider. Since the internal reference is 625mV, a divider with R4 = 500kΩ and R3 ≈ 920kΩ sets VRST = 1.8V (R3 = R4 × (1.8V / 0.625V − 1)). This configuration is explicitly validated in the "Monitoring Voltages Other Than VCC" section of the MAX6391KA44+ datasheet and ensures accurate secondary rail supervision.
What is the purpose of pins R1 and R2 on MAX6391KA44+, and how should they be used?
Pins R1 and R2 on MAX6391KA44+ provide internal 47kΩ pullup resistors connected to RESET1 and RESET2, respectively. They allow designers to tie each pin to a desired VOH voltage (e.g., 3.3V or 5V) to set the high-level reset signal voltage independently - eliminating external pullup resistors. This feature is unique to the MAX6391 variant and is detailed in the Pin Description and Applications Information sections for MAX6391KA44+.
Is MAX6391KA44+ suitable for operation at VCC = 1.2V, and does reset remain valid at that level?
Yes, MAX6391KA44+ is fully specified to operate at VCC = 1.2V (minimum per Absolute Maximum Ratings and Electrical Characteristics), and reset functionality is guaranteed valid down to VCC = 1.0V. This ensures reliable assertion of both RESET1 and RESET2 even during deep brownout events, a key specification confirmed in the "Guaranteed Reset Valid to VCC = 1V" feature and Electrical Characteristics table for MAX6391KA44+.
MAX6391KA44+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-8
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Multi-Voltage Supervisor
- Number of Voltages Monitored:
- 2
- Voltage - Threshold:
- 4.63V, 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
MAX6391KA44+ FAQ
1.How can I place an order for MAX6391KA44+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6391KA44+ 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 MAX6391KA44+ reliable?
The price and inventory of MAX6391KA44+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6391KA44+ is usually 5 days.
3.What payment methods are accepted for MAX6391KA44+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6391KA44+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6391KA44+?
MAX6391KA44+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6391KA44+ 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 MAX6391KA44+?
For technical support, including MAX6391KA44+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6391KA44+ requirements.
6.How does Aetrix verify that MAX6391KA44+ is sourced from the original manufacturer or authorized distributors?
All MAX6391KA44+ 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 MAX6391KA44+ meets industry standards.
7.What is the process for return or replacement of MAX6391KA44+?
All MAX6391KA44+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6391KA44+, 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 MAX6391KA44+ part is unused and in its original packaging.
Return procedure for MAX6391KA44+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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