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Analog Devices Inc./Maxim Integrated MAX6391KA23+
- Part No.:
- MAX6391KA23+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6391KA23+.pdf
- Description:
- IC SUPERVISOR 2 CHANNEL SOT23-8
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
MAX6391KA23+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced reset outputs, monitoring VCC (2.32V factory-fixed threshold) and RESET IN2 (adjustable down to 625mV), providing time-sequenced active-low open-drain RESET1 and RESET2 outputs for multi-rail power-up sequencing in embedded systems. It guarantees valid reset operation down to VCC = 1.0V, features internal 47kΩ pullup resistors on both reset outputs, and draws only 15µA typical supply current.
For engineers reviewing the MAX6391KA23+ datasheet, MAX6391KA23+ pinout, MAX6391KA23+ application, or MAX6391KA23+ equivalent, key selection considerations include its fixed 2.32V VCC reset threshold, 140ms minimum timeout on RESET1, capacitor-adjustable or fixed 140ms+ RESET2 delay, guaranteed operation at 1V VCC, and SOT23-8 package compatibility with space-constrained industrial and computing designs.
Technical Context
The MAX6391KA23+ implements two independent voltage-monitoring comparators: one dedicated to VCC with a factory-trimmed 2.32V threshold (VTH1), and a second high-impedance input (RESET IN2) referenced to a precise 625mV internal bandgap. RESET1 asserts solely on VCC undervoltage and deasserts after a fixed 140ms (min) timeout; RESET2 asserts if either VCC or RESET IN2 falls below their respective thresholds and deasserts after a timeout set by CSRT-either fixed (CSRT tied to VCC) or user-adjustable (CSRT to capacitor).
Its sequenced behavior is deterministic: during power-up, RESET1 deasserts first, followed by RESET2; during power-down, RESET2 asserts before RESET1. The device uses BiCMOS process technology (810 transistors), supports operation from -40°C to +85°C, and maintains reset validity even as VCC drops to 1.0V-enabling robust brownout detection in low-voltage systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Reset Threshold | 2.25V (min), 2.32V (typ), 2.38V (max) - factory-trimmed for precise 2.32V brownout detection on primary supply |
| RESET IN2 Threshold | 610mV–640mV - enables monitoring of secondary supplies as low as ~625mV via external resistor divider |
| RESET1 Timeout Period | 140ms (min), 200ms (typ), 280ms (max) - fixed internal timing ensures reliable processor hold-off after VCC recovery |
| RESET2 Timeout Period | 140ms (min) fixed when CSRT = VCC; user-adjustable via capacitor (e.g., 3.1ms with 1500pF) - supports flexible sequencing delays |
| Supply Current | 15µA (typ), 25µA (max) - ultra-low quiescent current extends battery life in always-on monitoring applications |
| Reset Valid Down To | VCC = 1.0V - guarantees functional reset assertion even during deep brownout conditions |
| Package | SOT23-8 - compact 8-pin surface-mount package (2.9mm × 2.8mm) suitable for dense PCB layouts |
Pinout & Package
MAX6391KA23+ is housed in an 8-pin SOT23 package (JEDEC MO178 compliant, 0.65mm pitch), with exposed pad not electrically connected. Pin 1 (RESET IN2) is marked by a dot; leads are gull-wing, coplanarity ≤ 0.1mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - RESET IN2 | Secondary supply monitor input | High-impedance comparator input referenced to 625mV; connects to external resistor divider for custom reset threshold |
| 2 - VCC | Main supply & master monitor input | Power supply pin and primary reset trigger; asserts both resets when falling below 2.32V threshold |
| 3 - CSRT | RESET2 timeout configuration node | Connect to VCC for fixed 140ms+ delay; connect to capacitor-to-ground for user-adjustable delay (e.g., 3.1ms @ 1500pF) |
| 4 - GND | Ground reference | Analog and digital ground return; must be low-impedance for stable comparator operation |
| 5 - RESET2 | Secondary sequenced reset output | Active-low open-drain output; deasserts only after RESET1 and after CSRT-defined delay - enforces strict power-up order |
| 6 - R2 | Internal pullup connection for RESET2 | 47kΩ internal resistor; tie to external VOH (e.g., 3.3V or 5V) to set RESET2 high-level voltage independently of VCC |
| 7 - RESET1 | Primary reset output | Active-low open-drain output; deasserts first after VCC recovery, initiating controlled system boot sequence |
| 8 - R1 | Internal pullup connection for RESET1 | 47kΩ internal resistor; tie to external VOH to define RESET1 high-level voltage, enabling mixed-voltage interface support |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent voltage monitoring | Simultaneously supervises primary (VCC @ 2.32V) and secondary (RESET IN2 @ 625mV) rails without shared sensing path |
| Guaranteed reset validity at 1.0V VCC | Ensures reliable reset assertion during severe brownout - critical for data integrity in nonvolatile memory systems |
| Internal 47kΩ pullup resistors on both RESET outputs | Eliminates need for external pullups; allows independent VOH setting (e.g., RESET1 to 3.3V, RESET2 to 5V) for mixed-supply designs |
| Sequenced reset timing control | Hardwired power-up order (RESET1 before RESET2) and power-down order (RESET2 before RESET1) prevent race conditions |
| Immunity to short negative VCC transients | Rejects glitches <100ns wide at ≥10mV overdrive - suppresses false resets from switching noise or ESD coupling |
Applications
| Industrial PLC Controllers | Multi-Rail Embedded Computers |
|---|---|
|
Use Scenario: Power sequencing for FPGA, ARM SoC, and analog front-end in programmable logic controllers operating in harsh environments. IC Role / Device Role / Timing Role: Primary supervisor ensuring FPGA config memory is held in reset until all 1.2V, 3.3V, and 5V rails stabilize, then releasing them in strict order. Use Value: Prevents configuration corruption and I/O contention by enforcing RESET1 (FPGA core) before RESET2 (peripheral I/O), with 140ms hold time guaranteeing rail stability. |
Use Scenario: Boot coordination in fanless embedded PCs with separate CPU core, I/O, and DDR memory rails. IC Role / Device Role / Timing Role: Dual-threshold monitor asserting RESET1 on main 3.3V rail and RESET2 on adjustable 1.8V DDR supply, with CSRT-timed delay. Use Value: Enables safe DDR initialization only after CPU core is fully operational - avoids bus contention and timing violations during cold start. |
| Network Print Server Modules | Medical Diagnostic Instrumentation |
|
Use Scenario: Reliable power-up of ARM-based print server with Ethernet PHY, USB host, and flash storage subsystems. IC Role / Device Role / Timing Role: Sequencing supervisor where RESET1 controls CPU/flash and RESET2 controls PHY/USB, with RESET IN2 monitoring isolated 2.5V PHY supply. Use Value: Guarantees PHY reset release occurs only after CPU firmware initializes USB drivers - eliminating enumeration failures and link flapping. |
Use Scenario: Safety-critical boot validation in portable ultrasound devices with battery-backed real-time clock and analog signal chain. IC Role / Device Role / Timing Role: Brownout detector with 1.0V reset validity, monitoring main 3.3V rail (VCC) and backup 1.8V RTC rail (via RESET IN2 divider). Use Value: Forces full system reset before RTC or ADC data corruption can occur - meeting IEC 62304 Class C software safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-voltage supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6391KA22+ | Factory-set VCC threshold = 2.12V–2.25V (typ 2.19V), 100mV lower than MAX6391KA23+'s 2.32V | Suitable for systems requiring earlier reset assertion on 2.2V nominal rails (e.g., some LPDDR interfaces) | Select MAX6391KA22+ only if design requires reset at ~2.19V; otherwise MAX6391KA23+ provides tighter margin for 2.3V–2.4V rails. |
| TLV809E23DBZR | Single-supply supervisor (2.32V threshold), no secondary monitor or sequenced outputs; SOT23-3 package | Lacks RESET IN2 monitoring and RESET2 sequencing - cannot replace dual-rail sequencing function | Use TLV809E23DBZR only for simple single-rail reset; MAX6391KA23+ is required when dual-voltage sequencing or slave-supply monitoring is needed. |
Compared with MAX6391KA22+, MAX6391KA23+ offers higher VCC threshold margin for 2.3V–2.4V systems; compared with TLV809E23DBZR, it uniquely delivers dual-input supervision and deterministic reset ordering - making it irreplaceable in multi-rail sequencing applications.
Availability
MAX6391KA23+ is available at Aetrix Electronics and suitable for industrial PLC controllers, multi-rail embedded computers, and network print server modules requiring stable component supply, long-term lifecycle assurance, and lead-free compliance.
Supply support for MAX6391KA23+ 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, computing, and communications markets.
The MAX6391/MAX6392 product line was designed specifically for deterministic dual-rail power sequencing in space-constrained embedded systems - addressing the need for reliable, low-power, and pin-efficient supervision where discrete solutions increase BOM cost and board area.
FAQ
What is the exact factory-trimmed VCC reset threshold voltage for MAX6391KA23+?
The MAX6391KA23+ has a factory-trimmed VCC reset threshold of 2.25V (minimum), 2.32V (typical), and 2.38V (maximum). This 2.32V nominal value is laser-trimmed during production and is confirmed in the Selector Guide table where MAX6391KA23 maps to "2.32" under Nominal Threshold (V). The device guarantees reset assertion whenever VCC falls below 2.25V across the full -40°C to +85°C temperature range.
Does MAX6391KA23+ support manual reset functionality like the MAX6392 variants?
No, MAX6391KA23+ does not include manual reset (MR) functionality. It is the MAX6391 variant, which features internal pullup resistors R1 and R2 on RESET1 and RESET2 but omits the MR pin (pin 8 is R1, not MR). Manual reset is exclusive to MAX6392 devices (e.g., MAX6392KA23+), where pin 8 is MR and pin 8 on MAX6391KA23+ is R1 - a fundamental variant distinction confirmed in the Pin Description table and Functional Diagram.
How is the RESET2 timeout period configured on MAX6391KA23+?
On MAX6391KA23+, the RESET2 timeout is configured via the CSRT pin (pin 3): connecting CSRT to VCC selects a fixed 140ms (minimum) timeout, while connecting CSRT to an external capacitor (e.g., 1500pF to ground) enables user-adjustable timing - calculated as tRP2 ≈ 2.08 × 10⁶ × CCSRT seconds. This dual-mode flexibility is intrinsic to the MAX6391 architecture and is explicitly documented in the Applications Information section and Electrical Characteristics table.
Can MAX6391KA23+ monitor a 1.2V supply as the secondary voltage (RESET IN2)?
Yes, MAX6391KA23+ can monitor a 1.2V supply on RESET IN2 using an external resistor divider. Since the internal RESET IN2 comparator threshold is fixed at 625mV, a divider with R3/R4 ratio ≈ 0.92 (e.g., R4 = 500kΩ, R3 = 460kΩ) scales 1.2V down to 625mV at the pin. This method is validated in the Applications Information section ("Monitoring Voltages Other Than VCC") and supported by the 50nA max input current specification, ensuring minimal loading on the monitored rail.
What is the purpose of pins R1 and R2 on MAX6391KA23+?
Pins R1 (pin 8) and R2 (pin 6) on MAX6391KA23+ are dedicated connections to internal 47kΩ pullup resistors for RESET1 and RESET2, respectively. They allow designers to tie each open-drain reset output to an external voltage rail (e.g., 3.3V or 5V) independent of VCC - enabling level-shifted reset signaling in mixed-voltage systems without adding external resistors. This feature is unique to the MAX6391 variant and is detailed in the Pin Description and Applications Information sections.
MAX6391KA23+ 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:
- 2.32V, 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
MAX6391KA23+ FAQ
1.How can I place an order for MAX6391KA23+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6391KA23+ 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 MAX6391KA23+ reliable?
The price and inventory of MAX6391KA23+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6391KA23+ is usually 5 days.
3.What payment methods are accepted for MAX6391KA23+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6391KA23+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6391KA23+?
MAX6391KA23+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6391KA23+ 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 MAX6391KA23+?
For technical support, including MAX6391KA23+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6391KA23+ requirements.
6.How does Aetrix verify that MAX6391KA23+ is sourced from the original manufacturer or authorized distributors?
All MAX6391KA23+ 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 MAX6391KA23+ meets industry standards.
7.What is the process for return or replacement of MAX6391KA23+?
All MAX6391KA23+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6391KA23+, 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 MAX6391KA23+ part is unused and in its original packaging.
Return procedure for MAX6391KA23+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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