Diodes Incorporated AP1509-33SL-13

Overview

AP1509-33SL-13 from Diodes Incorporated is a fixed-output 3.3V, 2A monolithic PWM buck DC-DC converter in SO-8 package, integrating a power switch and internal compensation to enable compact, high-efficiency step-down regulation from 4.75–22V input. It delivers ±1.5% output voltage accuracy at 2A load, operates at 150kHz ±15%, and includes thermal shutdown, current limiting, and logic-level ON/OFF control for embedded power rails in industrial and consumer systems.

For engineers reviewing the AP1509-33SL-13 datasheet, AP1509-33SL-13 pinout, AP1509-33SL-13 application, or AP1509-33SL-13 equivalent, key selection considerations include its fixed 3.3V output, 2A continuous load capability, SO-8 thermal performance (θ_JA = 70°C/W), shutdown quiescent current of 70–150µA, and compatibility with standard 47µH inductors and Schottky catch diodes.

Technical Context

The AP1509-33SL-13 implements voltage-mode non-synchronous PWM control with a built-in 2A N-channel MOSFET switch and internal 1.23V reference. Its feedback loop uses a resistive divider (not required for fixed 3.3V version) and compensates internally-eliminating external compensation components. The oscillator runs at 150kHz ±15%, enabling use of smaller passive filters than lower-frequency regulators.

Protection functions include cycle-by-cycle current limiting (trip point ≥3A) and thermal shutdown at ~150°C junction temperature. When current limit activates and V_FB drops below 0.5V, switching frequency reduces to 10–50kHz to limit power dissipation. Shutdown is asserted by pulling SD pin >2.0V (logic high), reducing supply current to ≤150µA.

Key Specifications

Pinout & Package

AP1509-33SL-13 is housed in a standard lead-free SO-8 (Small Outline-8) package with exposed pad not electrically connected. The package measures 4.90mm × 6.00mm × 1.45mm and features gull-wing leads compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output buck converter applications.

Compared with MP1584EN-LF-Z and LM2678SX-3.3/NOPB, the AP1509-33SL-13 offers the smallest footprint and simplest implementation for 3.3V/2A conversion up to 22V input, trading off higher current capability and input voltage range for reduced component count and layout effort.

Availability

AP1509-33SL-13 is available at Aetrix Electronics and suitable for industrial automation, USB-C peripheral power, automotive body electronics, and smart home device production requiring stable component supply and long-term manufacturability.

Supply support for AP1509-33SL-13 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for industrial, computing, and automotive markets.

The AP1509 series belongs to Diodes' monolithic DC-DC converter product line, designed specifically for cost-sensitive, space-constrained applications needing integrated switch and internal compensation-targeting embedded power rails where simplicity and rapid time-to-market are critical.

FAQ

What is the minimum input voltage required for stable 3.3V output at 2A?

The AP1509-33SL-13 requires a minimum input voltage of 4.75V to maintain regulation at full 2A load, as specified in the Recommended Operating Conditions table. Below this threshold, dropout occurs and output voltage collapses proportionally with input. This 4.75V minimum ensures sufficient headroom for the internal switch saturation voltage (~1.25V) and feedback control loop stability across temperature and load.

Can the FB pin be used to adjust the output voltage of the AP1509-33SL-13?

No-the AP1509-33SL-13 is a fixed 3.3V output variant with internal feedback divider; the FB pin is internally connected and must remain unconnected in circuit. Only the adjustable version (AP1509-SG-13) supports external resistor programming. Attempting to attach external resistors to FB on the -33SL-13 will disrupt regulation and may cause instability or overvoltage.

How does the current limit protection behave during overload?

When output current exceeds ~3A, the AP1509-33SL-13 enters cycle-by-cycle current limiting: the switch turns off mid-cycle to clamp peak inductor current. If V_FB then falls below 0.5V (indicating severe overload), the oscillator frequency reduces from 150kHz to 10–50kHz to limit average power dissipation and prevent thermal runaway-enabling safe, self-limiting operation until fault clears.

Is the AP1509-33SL-13 qualified for automotive applications?

The AP1509-33SL-13 is not AEC-Q100 qualified; Diodes lists it as NRND (Not Recommended for New Designs) per their ordering table. For automotive use, Diodes recommends contacting their sales team for AEC-Q100-qualified alternatives. This part meets industrial temperature range (-20°C to +85°C ambient) and RoHS/Green requirements but lacks automotive change control, PPAP documentation, or IATF 16949 manufacturing certification.