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Analog Devices Inc./Maxim Integrated MAX6391KA17+
- Part No.:
- MAX6391KA17+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Supervisors
- Package:
- SOT-23-8
- Datasheet:
-
MAX6391KA17+.pdf
- Description:
- IC SUPERVISOR 2 CHANNEL SOT23-8
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
MAX6391KA17+ from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced open-drain reset outputs, monitoring VCC (1.67V factory-fixed threshold) and adjustable RESET IN2 (625mV reference), delivering guaranteed reset validity down to VCC = 1V, 140ms min RESET1 timeout, and 15µA typical supply current for multivoltage power sequencing in industrial controllers and embedded systems.
For engineers reviewing the MAX6391KA17+ datasheet, MAX6391KA17+ pinout, MAX6391KA17+ application, or MAX6391KA17+ equivalent, key selection criteria include its fixed 1.67V VCC reset threshold, internal 47kΩ pullup resistors on both RESET1 and RESET2, CSRT-configurable RESET2 timeout, immunity to short negative VCC transients, and guaranteed operation across -40°C to +85°C.
Technical Context
The MAX6391KA17+ implements two independent voltage monitors: a primary comparator sensing VCC against a factory-trimmed 1.67V threshold (VTH1), and a secondary comparator sensing RESET IN2 against a precise 625mV internal reference (VTH2). RESET1 asserts only on VCC undervoltage and deasserts after a fixed 140ms minimum timeout; RESET2 asserts if either VCC or RESET IN2 falls below their thresholds and deasserts after a fixed 140ms minimum or capacitor-adjustable timeout via CSRT.
Its sequenced behavior is deterministic: during power-up, RESET1 deasserts first, then RESET2 follows after its timeout; during power-down, RESET2 asserts before RESET1. The device uses BiCMOS process (810 transistors), supports open-drain outputs with internal 47kΩ pullups (R1/R2), and guarantees valid reset assertion down to VCC = 1V - enabling reliable supervision in low-voltage systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Reset Threshold | 1.67V (factory-trimmed, ±3% over temp; sets master power-fail 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 (ultra-low quiescent current enables use in battery-backed or always-on monitoring applications) |
| Operating Voltage Range | 1.2V to 5.5V (supports wide input range while guaranteeing reset validity down to VCC = 1V) |
| Output Type | Open-drain RESET1 & RESET2 with internal 47kΩ pullup resistors (enables independent VOH level setting without external components) |
Pinout & Package
Package: 8-pin SOT23-8 (JEDEC MO-178 compliant; 3.00mm × 1.75mm × 1.30mm body; lead-free +T suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - RESET IN2 | Secondary supply monitor input | High-impedance comparator input referenced to 625mV; accepts external resistor divider to set custom reset threshold for slave supply |
| 2 - VCC | Main supply & master monitor input | Power supply pin and primary reset trigger; asserts both resets when falling below 1.67V; powers internal circuitry |
| 3 - CSRT | RESET2 timeout configuration node | Connect to VCC for fixed 140ms RESET2 timeout; connect to external capacitor for user-adjustable delay (tRP2 = 2.08×10⁶ × C) |
| 4 - GND | Analog/digital ground reference | Common return path for all internal comparators, timers, and output drivers; must be low-impedance |
| 5 - RESET2 | Secondary active-low reset output | Open-drain output asserted when VCC < 1.67V OR RESET IN2 < 625mV; timing controlled by CSRT connection |
| 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 high-state |
| 7 - RESET1 | Primary active-low reset output | Open-drain output asserted only on VCC < 1.67V; deasserts 140ms min after VCC exceeds threshold |
| 8 - R1 | Internal pullup connection for RESET1 | 47kΩ resistor internally connected to RESET1; tie to desired VOH voltage independently of R2 |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent voltage monitoring | Simultaneous supervision of master (VCC) and slave (RESET IN2) supplies with distinct thresholds and timing |
| Sequenced reset assertion/deassertion | Guaranteed RESET2-before-RESET1 assertion on power-down and RESET1-before-RESET2 deassertion on power-up |
| Internal 47kΩ pullup resistors | Eliminates need for external pullups; allows independent VOH level selection for RESET1 and RESET2 via R1/R2 connections |
| Reset validity to 1V VCC | Ensures reliable reset generation even during deep brownout conditions where VCC drops to 1V |
| Glitch-immune VCC sensing | Rejects negative VCC transients ≤100ns at 100mV overdrive, preventing false resets from noise or switching spikes |
Applications
| Industrial PLC Controllers | Embedded Multivoltage Systems |
|---|---|
|
Use Scenario: Power sequencing for FPGA + microcontroller subsystems with separate 1.2V core and 3.3V I/O rails. IC Role / Device Role / Timing Role: Supervises VCC (3.3V) and RESET IN2 (derived from 1.2V rail via divider); asserts RESET1 first, then RESET2 after configurable delay to ensure proper boot order. Use Value: Prevents FPGA configuration failure by enforcing strict power-up sequence; eliminates discrete supervisor ICs and timing RC networks. |
Use Scenario: Brownout protection in battery-powered IoT edge node with 1.8V MCU and 2.5V sensor interface. IC Role / Device Role / Timing Role: Monitors main 1.8V supply (VCC) and secondary 2.5V sensor rail (via RESET IN2 divider); asserts resets before VCC drops below 1.67V or sensor rail falls below programmed threshold. Use Value: Guarantees clean shutdown and data retention at VCC = 1V, extending usable battery range and avoiding corrupted sensor reads. |
| Network Equipment Line Cards | Medical Diagnostic Instrumentation |
|
Use Scenario: Dual-rail sequencing for ASIC-based packet processor requiring 1.0V core and 1.8V memory interface. IC Role / Device Role / Timing Role: Uses CSRT-connected capacitor to extend RESET2 timeout beyond RESET1, ensuring memory controller initializes after ASIC core is stable. Use Value: Eliminates risk of memory initialization errors due to race conditions; reduces BOM count by replacing two discrete supervisors. |
Use Scenario: Fail-safe reset coordination between safety-critical ARM Cortex-M7 and isolated analog front-end (AFE) powered from separate LDOs. IC Role / Device Role / Timing Role: Supervises main 3.3V AFE supply (VCC) and isolated 5V digital supply (RESET IN2); RESET2 asserts first on power loss to disable analog paths before digital logic resets. Use Value: Enforces hardware-enforced shutdown sequence required for IEC 62304 compliance; prevents hazardous analog output during partial power loss. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-supply supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6392KA17+ | Includes active-low manual reset (MR) input and push-pull RESET1; lacks R1 pullup (replaced by MR) | Required where field-service reset or system-level watchdog-triggered reset is needed | Select MAX6392KA17+ if manual reset functionality is mandatory; otherwise MAX6391KA17+ offers simpler pinout and dual pullups |
| TPS3808G17DBVR | Single-supply supervisor (1.7V threshold), no secondary monitor input; 200ms fixed timeout; push-pull output only | Suitable only for single-rail systems; cannot replace dual-monitoring function of MAX6391KA17+ | Use TPS3808G17DBVR only for cost-sensitive single-supply applications where RESET IN2 monitoring is unnecessary |
Compared with MAX6392KA17+, the MAX6391KA17+ provides dedicated R1/R2 pullup terminals for independent voltage-level control of both resets but omits manual reset; compared with TPS3808G17DBVR, it adds full dual-supply monitoring and sequenced timing - making it irreplaceable in multivoltage sequencing designs.
Availability
MAX6391KA17+ is available at Aetrix Electronics and suitable for industrial PLC controllers, embedded multivoltage systems, and network equipment line cards requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for MAX6391KA17+ 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, automotive, and communications applications.
The MAX6391/MAX6392 product line delivers integrated dual-supply supervisory circuits with sequenced reset outputs, targeting high-reliability embedded systems requiring deterministic power-up/down sequencing and brownout resilience.
FAQ
What is the exact VCC reset threshold voltage for MAX6391KA17+?
The MAX6391KA17+ has a factory-trimmed VCC reset threshold of 1.67V (typical), with guaranteed range of 1.62V to 1.71V over the full -40°C to +85°C temperature range. This value is laser-trimmed during production and is specific to the KA17 variant - confirmed in the Electrical Characteristics table and Selector Guide. The MAX6391KA17+ uses this fixed threshold to assert RESET1 whenever VCC falls below this level.
Can MAX6391KA17+ monitor a 1.2V supply as the secondary voltage?
Yes - the MAX6391KA17+ can monitor a 1.2V supply on RESET IN2 using an external resistor divider. Since the internal reference is 625mV, a divider with R3 = 460kΩ and R4 = 500kΩ yields VRST ≈ 1.2V. The MAX6391KA17+'s high-impedance RESET IN2 input draws only 50nA, minimizing divider current. This enables precise supervision of sub-1.8V rails without additional op-amps or comparators.
How is the RESET2 timeout period configured on MAX6391KA17+?
The RESET2 timeout on MAX6391KA17+ is configured via the CSRT pin: tying CSRT to VCC selects a fixed 140ms (minimum) timeout, while connecting CSRT to an external capacitor (to GND) enables user adjustment using tRP2 = 2.08 × 10⁶ × C. For example, a 1500pF capacitor yields ~3.1ms. The MAX6391KA17+ integrates a 600nA current source and 1.25V reference to implement this capacitor-based timing - no external timing resistors required.
Does MAX6391KA17+ support operation below 1.8V VCC?
Yes - the MAX6391KA17+ operates with VCC as low as 1.2V and guarantees valid reset assertion down to VCC = 1.0V. Its internal BiCMOS circuitry maintains comparator accuracy and timer functionality across this range. This capability is critical for modern low-voltage SoCs and FPGAs, and is explicitly verified in the Absolute Maximum Ratings and Electrical Characteristics tables for the MAX6391KA17+.
What is the purpose of the R1 and R2 pins on MAX6391KA17+?
R1 and R2 are dedicated terminals for the MAX6391KA17+'s internal 47kΩ pullup resistors connected to RESET1 and RESET2, respectively. Unlike standard open-drain supervisors, these pins allow designers to tie each reset output to a different VOH voltage (e.g., RESET1 to 3.3V for MCU, RESET2 to 5V for legacy peripheral) - enabling level-shifting without external components. This feature is unique to the MAX6391KA17+ among dual-supply supervisors.
MAX6391KA17+ 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:
- 1.67V, 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
MAX6391KA17+ FAQ
1.How can I place an order for MAX6391KA17+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6391KA17+ 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 MAX6391KA17+ reliable?
The price and inventory of MAX6391KA17+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6391KA17+ is usually 5 days.
3.What payment methods are accepted for MAX6391KA17+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6391KA17+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6391KA17+?
MAX6391KA17+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6391KA17+ 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 MAX6391KA17+?
For technical support, including MAX6391KA17+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6391KA17+ requirements.
6.How does Aetrix verify that MAX6391KA17+ is sourced from the original manufacturer or authorized distributors?
All MAX6391KA17+ 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 MAX6391KA17+ meets industry standards.
7.What is the process for return or replacement of MAX6391KA17+?
All MAX6391KA17+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6391KA17+, 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 MAX6391KA17+ part is unused and in its original packaging.
Return procedure for MAX6391KA17+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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