Analog Devices Inc./Maxim Integrated MAX4794EUS+T

Overview

MAX4794EUS+T from Maxim Integrated is a 300mA forward/reverse current-limited analog switch in a 4-pin SOT143 package, operating from 2.3V to 5.5V with 0.2Ω on-resistance and 14ms guaranteed fault-blanking time. It features autoretry behavior (not latch-off), reverse current protection, thermal shutdown at +150°C, and is designed for SDIO load switching in portable electronics.

For engineers reviewing the MAX4794EUS+T datasheet, MAX4794EUS+T pinout, MAX4794EUS+T application, or MAX4794EUS+T equivalent, key selection criteria include its 300mA current-limit threshold, autoretry recovery mode, absence of FLAG output, SOT143 footprint compatibility, and reverse-current limiting capability up to 450mA.

Technical Context

The MAX4794EUS+T implements dual-direction current limiting using internal sense resistors and reference comparators to detect forward and reverse overcurrent faults. Its autoretry architecture initiates a 98ms retry cycle after the 14ms blanking period expires under overload, enabling automatic re-enabling without host intervention.

It integrates undervoltage lockout (UVLO) with 2.2V rising-edge threshold and 100mV hysteresis, thermal shutdown with 15°C hysteresis, and reverse current protection that disables the switch if V_OUT > V_IN exceeds 450mA for longer than t_BLANK. No FLAG pin is present - fault status is inferred only via load behavior and retry cycling.

Key Specifications

Pinout & Package

MAX4794EUS+T uses a 4-pin SOT143 package (Package Code U4+2, Outline 21-0052), with exposed paddle not electrically connected. The compact 3mm × 1.5mm footprint supports high-density portable PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar current-limit switch applications.

Compared with MAX4792EUS+T and TPS22921YZPR, the MAX4794EUS+T uniquely delivers 300mA/450mA bidirectional limiting with autoretry in the industry-standard SOT143 footprint - enabling drop-in robustness upgrades without layout changes or firmware modifications.

Availability

MAX4794EUS+T is available at Aetrix Electronics and suitable for SDIO card power management, USB OTG peripheral control, GPS module sequencing, and Bluetooth/Wi-Fi coexistence gating requiring stable component supply across industrial temperature range (-40°C to +85°C).

Supply support for MAX4794EUS+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 demanding portable, industrial, and communications applications.

The MAX4789–MAX4794 family was engineered specifically for reliable, low-R_ON load switching in space-constrained mobile platforms - emphasizing fault resilience, bidirectional current control, and minimal external component count.

FAQ

What is the current-limit threshold of the MAX4794EUS+T?

The MAX4794EUS+T guarantees a minimum forward current limit of 300mA and a minimum reverse current limit of 450mA. These thresholds are specified across the full operating temperature range (-40°C to +85°C) and supply voltage (2.3V to 5.5V). The device enters current-limit mode when load current exceeds these values for longer than the 14ms blanking period, initiating its autoretry cycle.

Does the MAX4794EUS+T have a FLAG output pin?

No, the MAX4794EUS+T does not feature a functional FLAG output. Although Pin 1 is labeled "FLAG (N.C.)" in the SOT143 pinout, it is explicitly designated as "No Connection" - internally unconnected and electrically inactive. Fault status must be inferred indirectly through load behavior and autoretry timing, unlike MAX4793EUS+T which provides an open-drain FLAG signal.

What package type and footprint does the MAX4794EUS+T use?

The MAX4794EUS+T uses a 4-pin SOT143 package (Package Code U4+2, JEDEC Outline 21-0052), measuring 3.0mm × 1.5mm × 1.1mm. It shares pin compatibility with other SOT143 variants in the MAX4789–MAX4794 family, including MAX4789EUS+T and MAX4792EUS+T, enabling direct substitution where current-limit requirements align.

How does the autoretry function work in the MAX4794EUS+T?

In the MAX4794EUS+T, autoretry operates as follows: upon detecting sustained overcurrent beyond the 14ms blanking time, the switch turns off and waits for a 98ms retry interval before automatically re-enabling. If the overload persists, the cycle repeats; if cleared, the switch remains on. This eliminates need for host MCU intervention - unlike latch-off variants such as MAX4793EUS+T which require ON pin or power cycling to reset.

What is the maximum capacitive load the MAX4794EUS+T can drive safely?

The MAX4794EUS+T supports output capacitance up to approximately 100µF when VIN = 3.3V and t_BLANK = 14ms, calculated using C_MAX = (I_{FWD_MIN} × t_{BLANK_MIN}) / ΔV_IN. For reliable hot-swap operation with SDIO cards, a 0.1µF ceramic capacitor is required directly at the OUT pin, and larger bulk capacitance (e.g., 10µF–47µF) may be added downstream - provided total effective capacitance stays within this limit to avoid blanking timeout violations.