Analog Devices Inc./Maxim Integrated MAX1940EEE

Overview

MAX1940EEE from Maxim Integrated is a triple-channel USB power switch IC with autoreset and fault-blanking functionality, designed for upstream port protection in USB 2.0-compliant systems. It delivers guaranteed 500mA per channel, operates from 4V to 5.5V, consumes only 3µA standby current, and integrates independent thermal shutdown, current limiting (0.9A typ), and open-drain fault reporting (FAULTA/B/C). It is used in notebook/desktop USB hubs and docking stations requiring robust overcurrent and short-circuit protection.

For engineers reviewing the MAX1940EEE datasheet, MAX1940EEE pinout, MAX1940EEE application, or MAX1940EEE equivalent, key selection considerations include guaranteed 500mA per channel, 20ms fault-blanking tolerance for hot-swap capacitive loads, selectable active-high/active-low control logic via SEL pin, and independent per-channel shutdown and fault signaling - all in a 16-pin QSOP package rated for -40°C to +85°C.

Technical Context

The MAX1940EEE implements three independent high-side NMOS switches with integrated charge pump for gate drive, enabling operation from a single 4V–5.5V supply without external bias. Each channel features dual-mode current limiting: continuous mode (>1V V_OUT) at 0.9A (typ), and pulsed short-circuit mode (<1V V_OUT) at 1.2A peak, with 20ms blanking before fault assertion.

Its fault management includes independent open-drain FAULT outputs that assert low on UVLO (<3.4V), thermal shutdown (>160°C), or sustained current-limit faults; autoreset behavior sources 25mA and monitors V_OUT >0.5V for 20ms to re-enable the channel. The SEL pin configures ONA/ONB/ONC polarity (active-high or active-low), supporting flexible host MCU interface design.

Key Specifications

Pinout & Package

MAX1940EEE is housed in a 16-pin QSOP (Quad Small Outline Package) with 0.65mm lead pitch, optimized for compact USB port designs and thermal performance on standard PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple USB power switch applications.

Compared with TUSB2036IPWR and TPS2051BDBVR, the MAX1940EEE uniquely combines triple-channel integration, per-channel autoreset, 20ms fault blanking, and independent thermal shutdown in one 16-pin QSOP - delivering higher system-level reliability and lower design complexity for discrete USB port protection.

Availability

MAX1940EEE is available at Aetrix Electronics and suitable for USB hub designs, notebook computer port protection, docking station power management, and desktop motherboard USB controller interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX1940EEE 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 semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for computing, communications, and industrial applications.

The MAX1940EEE belongs to Maxim's USB power switch product line, engineered specifically to meet USB 2.0 compliance requirements while delivering robust fault protection, low quiescent power, and compact integration for space-constrained portable and embedded systems.

FAQ

What is the maximum continuous load current supported per channel of the MAX1940EEE?

The MAX1940EEE guarantees 500mA per channel under USB specifications. Its internal current limit is 0.9A (typical) with 1.2A peak in short-circuit mode. This ensures reliable operation with standard USB peripherals while protecting against sustained overloads - critical for maintaining compliance and preventing upstream supply collapse in the MAX1940EEE application circuit.

Does the MAX1940EEE support both active-high and active-low enable logic?

Yes. The MAX1940EEE uses the SEL pin to configure the polarity of all three ON inputs (ONA, ONB, ONC). When SEL is tied to V_IN, the ON inputs are active-high; when SEL is grounded, they become active-low. This flexibility allows seamless integration with various host microcontrollers without level-shifting - a key advantage confirmed in the MAX1940EEE functional description and Table 1.

How does the MAX1940EEE handle short-circuit conditions on a USB port?

Upon detecting V_OUT < 1V, the MAX1940EEE enters short-circuit current-limit mode (1.2A peak pulses) and starts a 20ms blanking timer. If the short persists beyond 20ms, FAULT asserts low and the channel latches off, sourcing only 25mA. Recovery occurs automatically when V_OUT rises above 0.5V for 20ms - a behavior fully documented in the MAX1940EEE's Output Fault Protection section and Figure 1 functional diagram.

What is the purpose of the 20ms fault-blanking feature in the MAX1940EEE?

The 20ms fault-blanking feature prevents false FAULT assertions during transient events like hot-swapping high-capacitance USB devices (e.g., external SSDs). It allows the MAX1940EEE to tolerate momentary current surges without interrupting operation - ensuring robustness in real-world USB usage. This timing is fixed, verified across temperature, and explicitly specified in the MAX1940EEE's Electrical Characteristics table.

Can the MAX1940EEE operate over the full industrial temperature range?

Yes. The MAX1940EEE is rated for -40°C to +85°C operation, as confirmed in the Ordering Information table and Absolute Maximum Ratings. All key parameters - including 500mA load current, 135mΩ R_ON, 3µA standby current, and 20ms fault blanking - are guaranteed across this extended temperature range, making it suitable for industrial computing and embedded USB applications.