Analog Devices Inc./Maxim Integrated MAX38908ATD+

Overview

MAX38908ATD+ from Maxim Integrated is a 4A, high-PSRR nMOS linear regulator with adjustable output (0.6V–5.0V), 51mV dropout at full load, ±1% DC accuracy over line/load/temperature, and dual-supply operation (0.9V–5.5V IN, 2.7V–20V BIAS). It delivers stable low-noise power to FPGA core rails, server μPs, and portable camera sensors requiring fast transient response and reverse-current protection.

For engineers reviewing the MAX38908ATD+ datasheet, MAX38908ATD+ pinout, MAX38908ATD+ application, or MAX38908ATD+ equivalent, this page provides verified package mapping (14-pin 3mm×3mm TDFN), confirmed feedback-based voltage programming, real-world PSRR values (78dB BIAS PSRR @10kHz), and validated alternative LDOs for multi-rail system design.

Technical Context

The MAX38908ATD+ uses an nMOS pass device architecture with separate IN and BIAS supplies-IN powers regulation while BIAS supplies internal circuitry, enabling ultra-low dropout and high PSRR even under low input headroom (300mV). Its feedback loop incorporates a BYP capacitor (1nF–100nF) to control soft-start slew rate and reduce reference noise.

Protection is implemented via integrated thermal shutdown (165°C trip, 150°C recovery), programmable inrush limiting, output overcurrent limit (4.4–6.8A), and active reverse-current blocking triggered when IN drops 6.5mV below OUT. The open-drain POK pin monitors FB voltage with 88–94% regulation threshold and requires external pullup (10kΩ–100kΩ).

Key Specifications

Pinout & Package

MAX38908ATD+ is housed in a 14-pin, 3mm × 3mm TDFN package (package code T1433+2C) with exposed pad (EP) for thermal dissipation. Pin 1 is top-left corner (marked dot), pin count proceeds counterclockwise. EP must be soldered to a solid ground plane for optimal thermal performance (θJA = 41°C/W on 4-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A8300RGRT and NCP1117ST50T3G, MAX38908ATD+ uniquely combines 4A capability, dual-supply flexibility, ±1% accuracy, and 78dB BIAS PSRR-making it irreplaceable where low-noise, high-current, and wide-input-range regulation are simultaneously required.

Availability

MAX38908ATD+ is available at Aetrix Electronics and suitable for FPGA power delivery, server microprocessor rails, and portable camera sensor applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MAX38908ATD+ 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 high-performance analog and mixed-signal ICs for demanding industrial, computing, and communications systems.

The MAX38907/MAX38908 family targets high-current, low-noise power regulation in space-constrained systems-specifically engineered for FPGA, server CPU, and imaging sensor applications needing fast transient response and robust fault protection.

FAQ

What is the minimum input voltage required for MAX38908ATD+ to regulate a 1.0V output?

The MAX38908ATD+ requires only 300mV of input-to-output headroom for good PSRR performance, so it can regulate a 1.0V output with as little as 1.3V on the IN pin. However, the absolute minimum IN voltage is 0.9V per datasheet-below 1.3V, the device enters dropout and loses regulation accuracy and PSRR. For reliable 1.0V operation, maintain VIN ≥1.3V and ensure BIAS ≥3.0V.

How do I configure the output voltage of MAX38908ATD+?

The MAX38908ATD+ uses external resistors on the FB pin to set output voltage: VOUT = 0.6V × (1 + R1/R2), where R2 connects FB to GND and R1 connects OUT to FB. Recommended values are listed in Table 2 of the datasheet-for example, 15kΩ (R1) and 10kΩ (R2) yield 1.5V. The FB pin has ±0.6% accuracy, contributing directly to overall ±1% output tolerance.

Does MAX38908ATD+ require a bypass capacitor on the BYP pin, and what value should I use?

Yes, MAX38908ATD+ requires a capacitor between BYP and OUT for stable operation and noise reduction. The recommended range is 1nF to 100nF; 47nF is commonly used for balanced soft-start slew rate (~1V/ms) and noise filtering. Values outside this range risk instability or excessive startup time. Avoid leakage >10nA on the BYP node, as it degrades output accuracy.

What protection features does MAX38908ATD+ include, and how do they activate?

MAX38908ATD+ integrates overcurrent limiting (trips at 4.4–6.8A), thermal shutdown (165°C trip, 150°C recovery), input/BIAS UVLO (0.45V IN, 2.55V BIAS), reverse-current blocking (activates when IN < OUT −6.5mV), and active discharge. These operate autonomously-no external components needed. For example, during short-circuit, current limit engages first; if heat builds, thermal shutdown overrides and cycles output until fault clears.

Can MAX38908ATD+ be used with only the IN supply, or is BIAS mandatory?

BIAS is mandatory for MAX38908ATD+ operation. Unlike conventional LDOs, it uses a separate BIAS rail (2.7V–20V) to power internal circuitry-including error amplifier, reference, and gate driver-while IN supplies only the pass device. Omitting BIAS prevents regulation entirely. BIAS must exceed VOUT by ≥2V; for a 1.2V output, BIAS ≥3.2V is required.