Analog Devices Inc./Maxim Integrated MAX38903BATB+

Overview

MAX38903BATB+ from Analog Devices is a 1A, low-noise LDO linear regulator in a 10-pin 3mm × 3mm TDFN package, delivering 5.5μVRMS output noise (10Hz–100kHz), ±1% DC output accuracy over load/line/temperature, and only 100mV dropout at full 1A load. It features resistor-programmable output voltage (0.6V–5.0V), active-high Power-OK (POK) signal, and 800Ω active discharge for fast output capacitor discharge - ideal for high-resolution data acquisition and high-end audio power rails.

For engineers reviewing the MAX38903BATB+ datasheet, MAX38903BATB+ pinout, MAX38903BATB+ application, or MAX38903BATB+ equivalent, key selection criteria include its 70dB PSRR at 10kHz, programmable soft-start via BYP capacitor, thermal/overcurrent protection, and compatibility with minimal 4μF output capacitance for stable operation in space-constrained, noise-sensitive systems.

Technical Context

The MAX38903BATB+ uses a pMOS pass transistor architecture with internal 0.6V reference and precision error amplifier, enabling ultra-low noise regulation and reverse current protection that activates when VIN drops 10mV below VOUT. Its POK circuit monitors output voltage against 91% (typ) of nominal regulation threshold and asserts high only after stable regulation is achieved.

Startup behavior is controlled by the BYP pin: a 0.01μF capacitor sets 5V/ms slew rate, and the soft-start current is fixed at 50μA from BYP to GND. The EN input has asymmetric thresholds (EN rising: 0.8–1.2V; falling: 0.4–0.7V) to prevent chatter during marginal enable transitions.

Key Specifications

Pinout & Package

MAX38903BATB+ is housed in a 10-pin, 3mm × 3mm TDFN package with exposed pad (EP) for thermal dissipation. Pin 1 is OUT (top-left corner, pad-side down); EP must be soldered to PCB ground plane with ≥4 thermal vias for θJA = 41°C/W (4-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A4700RGWR and LT3045EDD#PBF, the MAX38903BATB+ uniquely combines 1A output, integrated POK, and 800Ω active discharge in a compact TDFN - simplifying power sequencing in space-constrained, multi-rail systems without sacrificing noise or accuracy.

Availability

MAX38903BATB+ is available at Aetrix Electronics and suitable for high-resolution data acquisition, medical imaging front-ends, and optical transceiver biasing requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MAX38903BATB+ 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

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The MAX38903 family was designed specifically for noise-critical analog power domains in portable and high-precision instrumentation - emphasizing ultra-low noise, tight DC accuracy, and robust protection in miniature WLP and TDFN packages.

FAQ

What output voltage range does the MAX38903BATB+ support?

The MAX38903BATB+ supports resistor-programmable output voltages from 0.6V to 5.0V using an external feedback divider on the FB pin. Its internal 0.6V reference and low FB bias current (<100nA) ensure accurate setting across temperature; for example, R1 = 950kΩ and R2 = 300kΩ yields 2.5V output. This flexibility makes MAX38903BATB+ suitable for diverse analog rails without custom-trimmed variants.

How does the POK (Power-OK) function work on the MAX38903BATB+?

The MAX38903BATB+ features an active-high, open-drain POK pin that asserts high only when the output voltage reaches and maintains ≥91% of its nominal value. It requires an external pullup resistor (typically to 3.3V or 5V) and sinks ≤100μA in the low state. During startup, POK remains low until regulation is confirmed; it goes low again if overcurrent or thermal shutdown occurs. This behavior makes MAX38903BATB+ ideal for FPGA configuration sequencing and microcontroller reset timing.

Can the MAX38903BATB+ operate with less than 10μF output capacitance?

Yes - the MAX38903BATB+ is stable with a minimum 4μF ceramic output capacitor (X5R/X7R dielectric), including voltage derating. Unlike many LDOs requiring ≥10μF, this reduced capacitance requirement lowers cost and board area, especially valuable in portable designs. However, 10μF is recommended for optimal transient response and PSRR performance; the 4μF minimum assumes worst-case DC bias and temperature derating.

What is the purpose of the GS (Ground Sense) pin on the MAX38903BATB+?

GS (Ground Sense) on the MAX38903BATB+ provides Kelvin sensing of the true ground potential at the load, compensating for voltage drop across PCB traces between the IC's GND pin and the load's ground point. Connecting GS directly to the load's ground reference improves output regulation accuracy to ±1%, especially critical in high-current or long-trace applications like medical sensor front-ends. It must not be shorted to the main GND pin.

Does the MAX38903BATB+ include reverse current protection?

Yes - the MAX38903BATB+ integrates reverse current protection that disables the pMOS pass transistor when VIN falls 10mV below VOUT. This prevents backflow from output capacitors or backup batteries into the input rail during power-down transients, protecting upstream DC/DC converters and ensuring clean power sequencing. This feature is automatic and requires no external components, distinguishing MAX38903BATB+ from basic LDOs lacking such protection.