Analog Devices Inc./Maxim Integrated MAX6391KA17-T

Overview

MAX6391KA17-T from Maxim Integrated is a dual-voltage microprocessor supervisory circuit with sequenced open-drain reset outputs, factory-set 1.67V VCC reset threshold, 625mV adjustable secondary reset input (RESET IN2), and guaranteed reset validity down to VCC = 1.0V. It monitors master and slave supplies in multivoltage systems and enforces power-up sequencing where RESET1 deasserts before RESET2.

For engineers reviewing the MAX6391KA17-T datasheet, MAX6391KA17-T pinout, MAX6391KA17-T application, or MAX6391KA17-T equivalent, key selection criteria include sequenced reset timing control, dual-supply monitoring capability, internal 47kΩ pullup resistors for independent VOH level setting, and immunity to short negative VCC transients in industrial embedded power management.

Technical Context

The MAX6391KA17-T implements two independent voltage comparators: one fixed-threshold comparator for VCC (1.67V nominal) and one precision 625mV reference comparator for RESET IN2. RESET1 timing is fully internal and fixed at ≥140ms after VCC exceeds threshold; RESET2 timing is either fixed (CSRT tied to VCC) or user-adjustable via external capacitor on CSRT.

It uses BiCMOS process technology (810 transistors), supports operation from VCC = 1.2V to 5.5V, and guarantees functional reset assertion down to VCC = 1.0V. The device asserts RESET2 before RESET1 during power-down and ensures RESET2 deasserts only after RESET1 has deasserted during power-up - enforcing strict sequencing without external logic.

Key Specifications

Pinout & Package

MAX6391KA17-T is housed in an 8-pin SOT23-8 package (JEDEC MO-178 compliant), measuring 3.00mm × 1.75mm × 1.30mm, with gull-wing leads and lead-free finish (suffix "+T" denotes lead-free; "-T" is standard).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-supply supervisory applications.

Compared with MAX6392KA17-T, the MAX6391KA17-T provides dedicated internal pullups for both reset outputs but omits manual reset; compared with TPS3808G17DBVR, it delivers true dual-supply monitoring and hardware-enforced sequencing - making it irreplaceable in multivoltage systems requiring deterministic power-up order.

Availability

MAX6391KA17-T is available at Aetrix Electronics and suitable for industrial PLC power sequencing, server dual-rail power management, and medical imaging power subsystems requiring stable component supply, long-term lifecycle support, and guaranteed reset timing behavior.

Supply support for MAX6391KA17-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 industrial, computing, communications, and consumer applications.

The MAX6391/MAX6392 product line was engineered specifically for multivoltage microprocessor systems requiring hardware-guaranteed reset sequencing - eliminating reliance on software-controlled delays or external timing circuits.

FAQ

What is the factory-set VCC reset threshold voltage for MAX6391KA17-T?

The MAX6391KA17-T has a factory-set VCC reset threshold of 1.67V (nominal), with tolerance of 1.62V to 1.71V over temperature. This value is laser-trimmed during production and applies exclusively to the MAX6391KA17-T variant - other suffixes (e.g., KA46, KA22) correspond to different thresholds. The threshold is fixed and not user-adjustable.

Can MAX6391KA17-T monitor a 1.2V supply as the secondary voltage?

Yes - the MAX6391KA17-T can monitor a 1.2V supply using the RESET IN2 pin with an external resistor divider. Since the internal reference is 625mV, a divider ratio of ~1.92:1 (e.g., R3 = 470kΩ, R4 = 240kΩ) scales 1.2V down to 625mV at RESET IN2. The device guarantees valid operation with RESET IN2 input currents ≤50nA, minimizing loading on the monitored rail.

How does the CSRT pin configure RESET2 timeout behavior in MAX6391KA17-T?

In the MAX6391KA17-T, the CSRT pin selects RESET2 timeout mode: tying CSRT to VCC enables a fixed ≥140ms delay; connecting CSRT to a capacitor-to-ground enables user-adjustable timing (e.g., 3.1ms with 1500pF). The internal 600nA current source charges the capacitor, and timing follows tRP = 2.08×10⁶ × CCSRT. No external components are needed for fixed-mode operation.

Does MAX6391KA17-T provide internal pullup resistors for both reset outputs?

Yes - the MAX6391KA17-T integrates two 47kΩ internal pullup resistors: R1 connected to RESET1 and R2 connected to RESET2. These are accessible via pins 8 and 6 respectively. Connecting R1/R2 to an external voltage (e.g., 3.3V or 5V) sets the high-level output voltage (VOH) independently for each reset signal, enabling level-shifting without discrete components.

Is MAX6391KA17-T compatible with lead-free PCB assembly processes?

Yes - the MAX6391KA17-T is offered in lead-free packaging. The standard "-T" suffix indicates RoHS-compliant, lead-free finish per JEDEC J-STD-020. It supports reflow profiles up to 260°C peak temperature and meets moisture sensitivity level MSL3. For full compliance documentation, refer to Maxim's package specification 21-0078 for SOT23-8.