Analog Devices Inc./Maxim Integrated MAX15028ATB+T

Overview

MAX15028ATB+T from Maxim Integrated is a 1A low-dropout linear regulator with dual-supply operation: IN accepts 1.425V–3.6V while BIAS accepts 3V–5.5V, enabling operation even when IN drops to 0V. It delivers ±2% output accuracy from −40°C to +125°C, achieves 75mV typical dropout at 1A, and supports adjustable output from 0.5V to VIN. It is used in automotive dead-man LDO systems where continuous bias supply is critical during key-off.

For engineers reviewing the MAX15028ATB+T datasheet, MAX15028ATB+T pinout, MAX15028ATB+T application, or MAX15028ATB+T equivalent, key selection criteria include BIAS-supplied internal circuitry retention, thermal shutdown at 165°C, soft-start control via external capacitor, ceramic capacitor stability (1µF IN / 4.7µF OUT), and AEC-Q100 qualification for automotive use.

Technical Context

The MAX15028ATB+T uses a p-channel MOSFET pass device with 75mΩ typical on-resistance, eliminating base-drive current and enabling ultra-low quiescent current (60µA operating, 1.2µA shutdown under BIAS). Its internal architecture separates power path (IN→OUT) from control logic supply (BIAS), allowing uninterrupted regulation control during main rail collapse.

It integrates a 0.5V reference, error amplifier with soft-start ramp (5µA charge current), overcurrent limiting (1.4–2.0A), and thermal shutdown with 15°C hysteresis. The feedback loop is optimized for stability with ≥4.7µF ceramic output capacitance and achieves ≤15mV transient deviation for 500mA load steps.

Key Specifications

Pinout & Package

MAX15028ATB+T is housed in a thermally enhanced 10-pin TDFN package (3mm × 3mm) with exposed pad (EP) for optimal heat dissipation. The EP must be soldered to a large ground plane using multiple thermal vias.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A4700RGWR and NCP1117ST50T3G, the MAX15028ATB+T uniquely combines 1A current, BIAS-supplied control logic, AEC-Q100 qualification, and adjustable 0.5V–VIN output - making it the only option for automotive dead-man LDOs requiring zero-volt IN tolerance and full temperature compliance.

Availability

MAX15028ATB+T is available at Aetrix Electronics and suitable for automotive dead-man LDO systems, optical module biasing, and 5G base station RF power management requiring stable component supply across extended temperature and lifecycle demands.

Supply support for MAX15028ATB+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, automotive, and communications applications.

The MAX15028 is part of Maxim's automotive-qualified LDO family targeting always-on power domains where main supply collapse must not interrupt safety-critical monitoring or wake-up functions.

FAQ

What is the minimum input voltage required for MAX15028ATB+T to regulate with BIAS applied?

The MAX15028ATB+T operates with IN as low as 1.425V when BIAS is present at 3V–5.5V. This allows regulation even if IN sags to near-zero during key-off, as long as BIAS remains active. The device's undervoltage lockout on IN triggers at 1.04V (min), ensuring clean startup and shutdown behavior under marginal input conditions. The BIAS rail sustains internal circuitry regardless of IN status.

Can MAX15028ATB+T be used without the BIAS connection?

No - the MAX15028ATB+T requires a valid BIAS supply (3V–5.5V) to power its internal control circuitry. Unlike the MAX15027, it does not derive bias from IN. Attempting operation without BIAS will result in no regulation or undefined behavior. For single-rail operation, the MAX15027ATB+T variant should be selected instead.

What is the purpose of the I.C. pin on MAX15028ATB+T?

The I.C. pin (pin 4) on MAX15028ATB+T is internally connected and must be tied directly to GND. It serves no external functional role but is required for proper internal biasing and thermal performance. Leaving it floating or connecting it to any other node may cause malfunction or reduced reliability. This pin is not an enable, feedback, or current-sense terminal.

How does the soft-start function work on MAX15028ATB+T, and what capacitor value is recommended?

The MAX15028ATB+T implements soft-start by charging the SS pin with a 5µA current source; the rising SS voltage controls the regulation reference until it reaches 0.499V. A 0.1µF capacitor from SS to GND yields ~1ms ramp time. Larger values extend ramp duration linearly (CSS = 10⁻⁵ × tSS). This limits inrush current into downstream capacitance and prevents supply droop on shared rails.

Is MAX15028ATB+T compatible with ceramic output capacitors, and what is the minimum value required for 1A operation?

Yes - MAX15028ATB+T is fully stable with ceramic output capacitors. For 1A continuous operation, a minimum of 4.7µF ceramic capacitor with low ESR is required at the OUT pin. Smaller loads permit proportionally smaller capacitors (e.g., 1µF for 0.25A), per the formula COUT = 1µF × (IOUT_MAX / 0.25A). Using ≥10µF further improves transient response and reduces overshoot.