Diodes Incorporated AP1534SG-13

Overview

AP1534SG-13 from Diodes Incorporated is a PWM-controlled 2A step-down DC/DC converter with integrated P-channel MOSFET, 300kHz fixed-frequency operation, 3.6V–18V input range, and adjustable 0.8V–V_CC output. It delivers high efficiency (91% at 12V_IN/5V_OUT/2A), built-in soft-start, overcurrent/short-circuit protection, and thermal shutdown-designed for compact power supplies in PC motherboards and LCD monitors.

For engineers reviewing the AP1534SG-13 datasheet, AP1534SG-13 pinout, AP1534SG-13 application, or AP1534SG-13 equivalent, key selection criteria include internal PMOS R_DS(ON) (100 mΩ @ 12V), OCSET-adjustable current limit, EN-controlled enable/disable functionality, and SO-8 thermal performance (θ_JA = 127°C/W).

Technical Context

The AP1534SG-13 implements a fixed-frequency PWM control architecture with linear duty-cycle adjustment (0–99%), reference voltage source (0.8V ±2%), and internal error amplifier for closed-loop regulation. Its oscillator operates at 300kHz typical, dropping to 50kHz during overcurrent or short-circuit events to reduce stress and power dissipation.

Functional blocks include under-voltage lockout (UVLO active below 3.3V), thermal shutdown (150°C threshold, 55°C hysteresis), and internal compensation-eliminating external compensation components. The IC uses dual SW pins (5 & 6) and dual VSS pins (7 & 8) for enhanced current handling and EMI reduction in SO-8 package layout.

Key Specifications

Pinout & Package

AP1534SG-13 is housed in a RoHS-compliant, halogen-free SO-8 mini-package with exposed thermal pad connections on pins 5, 6 (SW), and 7, 8 (VSS). Dual SW and VSS pins reduce trace inductance and improve thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with MP1472GQ-P and TPS562201, the AP1534SG-13 offers simpler implementation for 3.6–18V inputs due to its integrated PMOS, OCSET-based current programming, and SO-8 thermal profile-making it optimal for cost-sensitive, space-constrained consumer electronics where input voltage stays within spec.

Availability

AP1534SG-13 is available at Aetrix Electronics and suitable for PC motherboards, LCD monitors, and ADSL modems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for AP1534SG-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 power management, signal integrity, and protection devices for consumer, industrial, and communications markets.

The AP1534 belongs to Diodes' PWM step-down converter product line, engineered for compact, high-efficiency DC-DC conversion in portable and embedded systems where integration, thermal performance, and ease of design are critical.

FAQ

What is the minimum recommended input voltage for reliable AP1534SG-13 operation?

The AP1534SG-13 features an under-voltage lockout (UVLO) that disables operation below 3.3V and re-enables only above 3.5V. Therefore, the minimum functional input voltage is 3.6V per datasheet specifications, ensuring stable PWM control and internal biasing across temperature and process variations.

How does the OCSET pin adjust overcurrent protection threshold?

The OCSET pin sinks a precise 90 µA current (typical). Connecting an external resistor R_OCSET between V_CC and OCSET sets the threshold voltage (V_OCSET = 90 µA × R_OCSET). When the sensed switch current causes the voltage across the internal MOSFET's R_DS(ON) to exceed V_OCSET, overcurrent protection activates and switches frequency to 50kHz.

Can AP1534SG-13 be used without an external Schottky diode?

No-the AP1534SG-13 integrates only a P-channel high-side MOSFET and requires an external Schottky diode (e.g., B240A) for the freewheeling path. Unlike synchronous buck converters, it lacks a low-side N-MOSFET; omitting the diode will cause catastrophic failure during discontinuous conduction mode or light loads.

What PCB layout practices maximize thermal performance in SO-8?

Maximize copper area under pins 5, 6 (SW) and 7, 8 (VSS), connect them directly to inner-layer ground planes using multiple thermal vias, and avoid routing sensitive FB traces near inductors. Per datasheet, use ≥2 oz copper with minimum recommended pad dimensions (X=0.802 mm, Y=1.505 mm) and ensure solder mask opening over thermal pad for optimal heat transfer.