Analog Devices Inc./Maxim Integrated MAX38909ATD+T

Overview

MAX38909ATD+T from Maxim Integrated is a 2A, fast-transient-response nMOS linear regulator with ±1% output accuracy over line/load/temperature, 27mV dropout at 2A (WLP), and dual-supply architecture (0.9V–5.5V IN, 2.7V–20V BIAS). It delivers stable low-noise power to FPGA core rails, server microcontrollers, and portable camera sensors requiring tight regulation under dynamic load steps.

For engineers reviewing the MAX38909ATD+T datasheet, MAX38909ATD+T pinout, MAX38909ATD+T application, or MAX38909ATD+T equivalent, this page provides verified package mapping (14-pin 3mm×3mm TDFN), confirmed feedback-programmable output (0.6V–5.0V), validated PSRR (52dB @10kHz, 300mV headroom), and real-world protection features including reverse-current blocking and monotonic soft-start.

Technical Context

The MAX38909ATD+T uses an nMOS pass device with separate BIAS rail to decouple gate drive from input voltage, enabling high PSRR and ultra-low dropout across wide VIN/VBIAS combinations. Its error amplifier references a precision 0.6V internal bandgap and drives the gate through a dedicated BYP node for noise filtering and slew-rate control.

Protection is implemented via integrated circuits: thermal shutdown triggers at +165°C (hysteresis to +150°C), output current limiting activates at 2.8A (typ), and reverse-current detection disables the pass element when VIN drops 6.5mV below VOUT - preventing body-diode conduction and ensuring safe power-down sequencing.

Key Specifications

Pinout & Package

MAX38909ATD+T is housed in a 14-pin, 3mm × 3mm TDFN package with exposed pad (EP) for thermal management. Pin numbering follows standard top-view orientation with EP soldered to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A8300RGRT and NCP1117ST50T3G, the MAX38909ATD+T uniquely combines dual-supply operation, sub-30mV dropout, and integrated reverse-current blocking - making it the only option among the three capable of powering modern FPGA cores from partially collapsed input rails while maintaining sequencing integrity.

Availability

MAX38909ATD+T is available at Aetrix Electronics and suitable for FPGA core power, server microcontroller rails, and portable camera sensor applications requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for MAX38909ATD+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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for demanding industrial, communications, and computing applications.

The MAX38909 product line was designed specifically for high-current, low-noise power delivery in space-constrained systems where traditional LDOs fail - targeting FPGA, ASIC, and SoC core rails needing ±1% accuracy, fast transient response, and robust fault protection.

FAQ

What is the minimum input-to-output voltage headroom required for MAX38909ATD+T to maintain regulation at 2A?

The MAX38909ATD+T achieves 27mV dropout at 2A load when using the WLP package and appropriate BIAS voltage (e.g., VBIAS = 12V, VOUT = 5.0V). In the TDFN package (MAX38909ATD+T), dropout is 36mV under identical conditions. Full PSRR performance (52dB @10kHz) is maintained with only 300mV headroom, but regulation itself is sustained down to the specified dropout voltage.

How does the BIAS pin function in MAX38909ATD+T, and what happens if it's left unconnected?

The BIAS pin supplies gate drive voltage to the nMOS pass transistor independently of the IN rail. It must be connected to a stable 2.7V–20V source ≥2.0V above the target VOUT; leaving it unconnected prevents the regulator from enabling. The MAX38909ATD+T draws 1.6mA BIAS current at 2A load and includes BIAS UVLO (2.45V–2.65V) to ensure safe startup and shutdown sequencing.

Can MAX38909ATD+T be used to generate a 0.8V output, and what feedback resistors are recommended?

Yes, the MAX38909ATD+T supports 0.6V–5.0V programmable output via external resistors. For 0.8V, use R1 = 15.0kΩ (bottom) and R2 = 4.99kΩ (top), yielding 0.799V per Table 1 in the datasheet. Both resistors should be 1% tolerance or better to preserve the ±1% overall output accuracy specification of the MAX38909ATD+T.

Does MAX38909ATD+T provide reverse-current protection, and how is it implemented?

Yes, the MAX38909ATD+T includes active reverse-current protection that disables the pass device when VIN falls 6.5mV below VOUT, preventing current flow through the body diode. This feature protects against power-down transients in systems with large output capacitance and is confirmed in the Electrical Characteristics table (IN Reverse-Current Threshold = 700mA) and Functional Diagram.

What thermal design considerations are critical for MAX38909ATD+T in a 2A, 1.2V output application?

For a 2A/1.2V output with 3.3V input, power dissipation is (3.3V – 1.2V) × 2A = 4.2W. Using the TDFN package's θJA = 41°C/W (4-layer board), junction temperature rise is 172°C - exceeding the 125°C limit. Therefore, the exposed pad (EP) must be connected to a large GND copper area with ≥6 thermal vias to reduce effective θJA; derating or forced air may also be required for sustained 2A operation.