Analog Devices Inc./Maxim Integrated MAX6819UT

Overview

MAX6819UT from Maxim Integrated is a dual-voltage power-supply sequencer IC that monitors a primary supply (e.g., 3.3V) and controls an external n-channel MOSFET to enable a secondary supply (e.g., 1.8V) only after the primary exceeds a 0.618V threshold. It features a fixed 200ms delay from primary-good to secondary-enable, logic-driven EN input, internal charge pump for +5.5V gate drive, and operates across –40°C to +125°C in automotive systems.

For engineers reviewing the MAX6819UT datasheet, MAX6819UT pinout, MAX6819UT application, or MAX6819UT equivalent, this device is selected for precise local voltage sequencing where VI/O must power before VCORE, transient-immune operation in multivoltage boards, and minimal external component count in space-constrained SOT23-6 layouts.

Technical Context

The MAX6819UT uses an internal 0.618V reference and comparator to monitor VCC1 via the SETV pin, enabling GATE only when VCC1 exceeds the threshold. Its EN input provides TTL/CMOS-compatible logic control with immediate GATE disable on low assertion.

A built-in charge pump generates VCC2 + 5.5V at GATE to fully enhance external n-channel MOSFETs, ensuring RDS(ON) remains low and avoiding linear-region operation. UVLO (1.875V–2.125V) prevents operation unless at least one supply exceeds the lockout level.

Key Specifications

Pinout & Package

MAX6819UT is housed in a 6-pin SOT23-6 package with exposed pad (not thermally enhanced), footprint-compatible with JEDEC MO-178AA. Pin 1 is marked with a dot; pin numbering follows standard SOT23 top-view convention.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power-supply sequencing applications.

Compared with MAX6820UT-T and TPS3808G125DBVR, the MAX6819UT delivers integrated gate drive and fixed-timing certainty ideal for cost-sensitive, high-volume dual-rail systems where layout simplicity and deterministic behavior are prioritized over configurability.

Availability

MAX6819UT is available at Aetrix Electronics and suitable for automotive ECUs, industrial PLCs, and embedded computing platforms requiring stable component supply, guaranteed automotive temperature operation, and minimal external components for voltage sequencing.

Supply support for MAX6819UT 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 automotive, industrial, and communications markets.

The MAX6819UT belongs to Maxim's power-supply sequencer product line, engineered specifically for local, dual-rail voltage sequencing in systems where primary and secondary supplies originate from non-sequenced sources like silver-box PSUs or shared bus architectures.

FAQ

What is the function of the EN pin on the MAX6819UT?

The EN pin on the MAX6819UT is an active-high logic input that enables or disables GATE drive. When EN is driven high (≥2.0V), the device initiates the 200ms delay and activates GATE after the delay-provided VCC1 exceeds the SETV threshold. When EN is pulled low (≤0.4V), GATE is immediately disabled regardless of supply status. This allows microcontrollers or system controllers to gate sequencing externally, making MAX6819UT suitable for dynamic power management schemes in real-time embedded systems.

Can the MAX6819UT monitor VCC2 instead of VCC1 as the primary supply?

Yes-the MAX6819UT does not assign fixed roles to VCC1 or VCC2. Either supply can serve as the monitored primary source, provided it exceeds the UVLO threshold (≥2.125V) and is connected to the SETV resistor divider. For example, VCC2 (e.g., 5V) may be monitored to enable VCC1 (e.g., 3.3V) downstream. The functional diagram and pin description confirm symmetric supply handling, and the datasheet explicitly states "either supply may act as the primary source, regardless of voltage level." This flexibility is intrinsic to MAX6819UT design.

What is the maximum gate capacitance the MAX6819UT can drive reliably?

The MAX6819UT is characterized to drive gate capacitances up to 1500pF with specified tON (0.5–10ms) and tOFF (30µs) performance, as confirmed in the Typical Operating Characteristics plots and Electrical Characteristics table. Driving larger capacitive loads may extend turn-on time beyond 10ms and reduce effective gate voltage due to charge pump current limits (~500nA). For reliable operation, select MOSFETs with Qg ≤ 20nC at VGS = 5.5V-ensuring compatibility with MAX6819UT's internal charge pump without external boost circuitry.

Does the MAX6819UT require external capacitors for its charge pump?

No-the MAX6819UT integrates a self-contained charge pump that requires no external capacitors. The charge pump generates VCC2 + 5.5V at the GATE pin using on-chip switching and flying capacitors, eliminating the need for external ceramic or tantalum storage caps. This simplifies layout, reduces bill-of-materials count, and improves reliability in high-vibration environments. The datasheet explicitly states "the internal charge pump does not require external capacitors," and typical operating circuits show zero external components connected to GATE or internal pump nodes.

How does the MAX6819UT handle negative voltage transients on the SETV pin?

The MAX6819UT exhibits immunity to short-duration negative-going transients on the SETV pin, with maximum tolerable pulse width inversely proportional to overdrive magnitude: e.g., up to 16µs at 0.1V below threshold (VTH − VSETV = 0.1V), per Figure 5 in the datasheet. This robustness prevents false disable events during board-level noise or supply bounce. Transient rejection is achieved via internal hysteresis (−1% on SETV threshold) and comparator slew-rate limiting, making MAX6819UT suitable for electrically noisy automotive and industrial environments where rail integrity cannot be fully guaranteed.