Analog Devices Inc./Maxim Integrated MAX38909ANL+T

Overview

The MAX38909ANL+T from Maxim Integrated is a 2A, nMOS low-dropout linear regulator with fast transient response and high PSRR, designed for precision power delivery in noise-sensitive systems. It operates from 0.9V to 5.5V input and 2.7V to 20V BIAS supply, delivers ±1% output accuracy over line/load/temperature, maintains regulation with only 27mV dropout at 2A (WLP package), and supports programmable output voltage from 0.6V to 5.0V via external resistors - enabling use in FPGA core rails and medical instrumentation power stages.

For engineers reviewing the MAX38909ANL+T datasheet, MAX38909ANL+T pinout, MAX38909ANL+T application, or MAX38909ANL+T equivalent, key selection criteria include its dual-supply architecture (IN + BIAS), 15mV load transient excursion at 2A, 52dB IN PSRR at 10kHz with 300mV headroom, reverse-current protection threshold of ~700mA, and compatibility with 10μF minimum output capacitance using X7R MLCCs.

Technical Context

The MAX38909ANL+T employs an nMOS pass device with separate IN and BIAS supplies: IN powers the regulation loop and load path (0.9V–5.5V), while BIAS powers internal circuitry (2.7V–20V), decoupling control logic from input rail instability. Its error amplifier references a stable 0.6V internal bandgap and uses a BYP pin-connected capacitor (1nF–100nF) to set monotonic soft-start slew rate and improve high-frequency PSRR.

Protection is implemented via integrated circuits including thermal shutdown (trip at +165°C, restart at +150°C), output overcurrent limiting (2.8A typical), active discharge (70Ω pull-down on OUT when disabled), and reverse-current blocking triggered when IN drops 6.5mV below OUT - preventing body-diode conduction during input collapse with large COUT.

Key Specifications

Pinout & Package

The MAX38909ANL+T is packaged in a 5 × 3 bump, 0.4mm pitch WLP (package code N151C2+1), with exposed thermal pad not present (unlike TDFN). This ultra-compact package targets space-constrained portable and medical devices.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TPS7A8300RGRT and NCP1117ST50T3G, the MAX38909ANL+T uniquely combines 2A current, dual-supply architecture (IN + BIAS), ±1% accuracy, and integrated reverse-current blocking - making it the only option among the three suitable for high-reliability, multi-rail FPGA and medical imaging systems requiring robust fault handling and precise sequencing.

Availability

The MAX38909ANL+T is available at Aetrix Electronics and suitable for FPGA core power, medical imaging sensor bias, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX38909ANL+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 high-performance analog and mixed-signal ICs for demanding industrial, medical, and communications applications.

The MAX38909ANL+T belongs to Maxim's high-PSRR, fast-transient LDO family targeting noise-critical power rails in FPGAs, DSPs, and precision instrumentation - emphasizing supply independence, accuracy, and robust protection.

FAQ

What is the minimum output capacitance required for stable operation of the MAX38909ANL+T?

The MAX38909ANL+T requires a minimum effective output capacitance of 10μF, using X7R multilayer ceramic capacitors (MLCCs). Stability is guaranteed with 22μF or greater, placed as close as possible to the OUT and GND pins. Lower values risk oscillation or degraded transient response, especially under 2A load steps. The MAX38909ANL+T does not require ESR tuning, unlike older LDO architectures.

How does the BIAS pin function in the MAX38909ANL+T, and what happens if it is unconnected?

The BIAS pin powers the MAX38909ANL+T's internal control circuitry independently of the IN pin. It must be connected to a stable 2.7V–20V supply, at least 2.0V above the target VOUT. If left unconnected or below UVLO threshold (2.45V), the MAX38909ANL+T will not regulate - EN will be ignored, POK stays low, and OUT remains inactive. BIAS enables operation even during IN brownouts, a key differentiator from single-supply LDOs.

Can the MAX38909ANL+T be used with a 0.6V output voltage, and what feedback resistor values are recommended?

Yes, the MAX38909ANL+T supports 0.6V output - the minimum regulated voltage, equal to its internal feedback reference. To achieve this, connect FB directly to OUT (R1 = 0Ω, R2 open), or use R1 = 15kΩ and R2 = 0Ω. For higher accuracy, 1% or better resistors are mandatory; the MAX38909ANL+T's ±1% output accuracy assumes proper resistor tolerance and layout. Table 1 in the datasheet confirms 0.6V is supported.

What is the purpose of the BYP pin on the MAX38909ANL+T, and how does capacitor selection affect performance?

The BYP pin connects a capacitor (1nF–100nF) between OUT and BYP to filter reference noise and control soft-start slew rate. A 10nF capacitor yields ~5V/ms startup; larger values slow ramp-up to limit inrush current. BYP also improves high-frequency PSRR and transient response. Leakage >10nA on BYP degrades output accuracy, so low-leakage C0G/NP0 ceramics are preferred over X7R for this node.

Does the MAX38909ANL+T provide reverse-current protection, and how is it implemented?

Yes, the MAX38909ANL+T provides active reverse-current protection. When VOUT exceeds VIN by >6.5mV, an internal detector opens a switch in series with the nMOS pass device's body diode, blocking reverse current flow. This prevents >700mA backfeed during input collapse - critical when large output capacitors are used in battery-powered or hot-swap systems. Protection is automatic and requires no external components.