Analog Devices Inc./Maxim Integrated MAX8556ETE+T

Overview

The MAX8556ETE+T from Maxim Integrated is a 4A ultra-low-input-voltage LDO regulator featuring an internal p-channel MOSFET pass transistor, adjustable output (0.5V to VIN − 0.2V), 100mV typical dropout at 4A, ±1% output accuracy over load/line/temperature, and a logic-controlled POK output for power-good monitoring in high-density point-of-load systems.

For engineers reviewing the MAX8556ETE+T datasheet, MAX8556ETE+T pinout, MAX8556ETE+T application, or MAX8556ETE+T equivalent, this device is selected for low-headroom, high-current DC-DC post-regulation in servers, optical modules, and base station RF power stages where input voltage can be as low as 1.425V and thermal performance under 4A load is critical.

Technical Context

The MAX8556ETE+T uses a 25mΩ p-channel MOSFET pass element enabling stable regulation down to 1.425V input without charge pump or external bias supply. Its error amplifier regulates FB to 0.500V (±5mV) with <1µA input bias, supporting precise resistor-divider-based output programming.

It integrates foldback short-circuit protection (3A max during fault), thermal shutdown at +160°C (recovery at +115°C), and a 100µs soft-start. The open-drain POK output asserts high only when VOUT remains within ±10% of nominal for ≥25µs, providing glitch-immune power-status signaling.

Key Specifications

Pinout & Package

Package: 16-pin TQFN (5mm × 5mm) with exposed thermal paddle (EP), RoHS-compliant, lead-free.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-current LDO applications.

Compared with TPS7A8300RGRT and NCP1117ST50T3G, the MAX8556ETE+T uniquely combines 4A delivery at 1.425V input, integrated POK, −40°C to +105°C operation, and 100mV dropout - making it irreplaceable in thermally constrained, high-reliability point-of-load designs requiring autonomous power validation.

Availability

MAX8556ETE+T is available at Aetrix Electronics and suitable for server power delivery, optical module biasing, 5G RF front-end regulation, and industrial FPGA I/O supply applications requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX8556ETE+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 industrial, communications, and computing applications.

The MAX8556ETE+T belongs to Maxim's ultra-low-input-voltage LDO family, engineered specifically for high-current, low-headroom point-of-load regulation in next-generation datacenter and telecom infrastructure where traditional LDOs fail to operate.

FAQ

What is the minimum input voltage required for the MAX8556ETE+T to regulate a 1.2V output?

The MAX8556ETE+T requires a minimum input voltage of 1.425V per its absolute rating and functional specification. For a 1.2V output, the dropout margin is 225mV - well above the 100mV typical dropout at 4A, ensuring stable regulation. Operation below 1.425V is not guaranteed and may result in undervoltage lockout activation or loss of regulation. The MAX8556ETE+T datasheet explicitly defines 1.425V as the lower limit of the input voltage range.

Does the MAX8556ETE+T require external capacitors, and what are the recommended values?

Yes, the MAX8556ETE+T requires external input and output capacitors for stability and transient performance. The datasheet specifies 2 × 10µF ceramic capacitors (X5R/X7R, ≤50mΩ ESR) from IN to GND and 2 × 10µF low-ESR ceramics from OUT to GND. For 4A loads, this configuration ensures loop stability across −40°C to +105°C. Smaller capacitance may be used only if load current is reduced below 4A, but full-rated performance requires the specified values. The MAX8556ETE+T will not meet its published specifications without these capacitors.

How does the POK output of the MAX8556ETE+T behave during thermal shutdown?

During thermal shutdown, the MAX8556ETE+T's POK output is actively pulled low - not high-impedance. This behavior is explicitly defined in the Pin Description and Detailed Description sections: "POK is low when the IC is in shutdown mode" and "If the output voltage falls/rises outside [±10%] range or the IC experiences thermal fault, POK is internally pulled low." The POK signal thus serves as a combined fault indicator for both output regulation failure and thermal overload, simplifying system-level fault detection without additional monitoring circuitry.

Can the MAX8556ETE+T be used in parallel to increase output current beyond 4A?

No, the MAX8556ETE+T is not designed for parallel operation. It lacks current-sharing features such as current-sense outputs, master-slave synchronization, or droop compensation. Attempting to parallel multiple MAX8556ETE+T units risks unequal current distribution, thermal runaway, and premature failure due to mismatched dropout voltages and load-transient responses. For >4A requirements, a single higher-current regulator or a multiphase buck converter is the appropriate architectural choice - the MAX8556ETE+T functions strictly as a monolithic 4A solution.

What is the thermal resistance (θ_JA) of the MAX8556ETE+T in standard JEDEC conditions?

The MAX8556ETE+T has a junction-to-ambient thermal resistance (θ_JA) of 37.5°C/W under JEDEC JESD51-7 4-layer board conditions (76.2mm × 76.2mm, 2oz Cu, 9 thermal vias). This value is derived from its specified maximum power dissipation of 2667mW at T_A = +70°C and T_J(MAX) = +150°C. Achieving this θ_JA requires strict adherence to the recommended PCB layout: exposed paddle soldered to solid GND plane with ≥9 thermal vias (12mil diameter, 1mil plating), and removal of solder mask over thermal pad areas.