In industrial control, communication equipment, and battery-powered systems, a stable and efficient power converter is essential for reliable system operation. XBL's XBL1507B series of step-down DC-DC converters offer a simple, reliable, and cost-effective power solution for a wide range of medium-voltage step-down applications. These converters feature a 3A output, a wide input range of 4.5V to 40V, a fixed 150kHz frequency, and integrated power transistors and protection features.

1. New product recommendation: XBL1507B series

The XBL1507B is a fixed 150kHz switching frequency PWM step-down converter, featuring integrated, optimized power transistors capable of continuous output of 3A. It offers excellent linearity and load regulation. Its control circuit allows for linear adjustment from 0% to 100%, and includes enable control, over-current protection, short-circuit protection, and thermal shutdown. In the event of over-current or short-circuit, the frequency automatically drops to 50kHz, effectively reducing power consumption and enhancing system reliability.

II. Key Features:

The input voltage range is 4.5V to 40V, compatible with 12V, 24V, and 36V power systems.

High current output: 3A continuous output current, suitable for most medium-power load requirements.

Output Voltage: 3.3V, 5V, 12V, and adjustable version (1.23V~37V)

High Efficiency: Typical efficiency of 73% (3.3V), 80% (5V), and 90% (12V) @ 3A

Fixed switch frequency: 150 kHz, with a fixed noise spectrum, making filtering easy.

Built-in protection: over-current protection, short-circuit protection, thermal shutdown.

Allows for: TTL level shutdown capability, extremely low standby current.

Package: TO252-5L, with excellent thermal performance.

III. Application scenarios:

Portable DVD player, LCD display/TV

Battery charger

ADSL modems, telecommunications/networking equipment

Industrial control power supply

Automotive electronic devices

IV. Circuit Design Guidelines

Typical application circuits

The following diagram shows a typical application circuit for the XBL1507B, with an input voltage of 8V to 40V and an output of 5V/2A. The circuit requires only an inductor, capacitor, diode, and a feedback resistor (for adjustable versions).

5. Guidance on vehicle selection

Note: The fixed-output version already includes an internal voltage divider, eliminating the need for an external feedback resistor. The adjustable version requires an external R1 and R2 to set the output voltage.

6. Recommendations for PCB design

To ensure the stable operation and optimal performance of the XBL1507B, the PCB layout should adhere to the following guidelines:

The input capacitor should be placed close to the VIN and GND pins. The input bypass capacitor (such as a 220µF electrolytic capacitor in parallel with a 0.1µF ceramic capacitor) must be placed directly adjacent to the chip pins to minimize input ripple and switching noise.

The power circuit should be as short as possible: The area of the circuit consisting of the switch node, the freewheeling diode, the output inductor, and the output capacitor should be minimized to reduce EMI.

The feedback path should be located away from noise sources. The FB pin should be treated as a high-impedance node, and the feedback divider resistor should be placed close to the FB pin and away from sources of noise such as the SW and inductor.

Grounding: Utilizes single-point grounding or power/signal ground separation, with the grounds converging at the input capacitor ground.

Thermal Design: The TO252-5L package requires the heat sink to be attached to a sufficiently large area of copper foil, and utilizes vias to connect to the underlying copper foil for enhanced heat dissipation.

Enable pin handling: If the EN function is not used, the pin can be left floating (with a default low-level state enabled internally) or controlled via a pull-up/pull-down resistor.

VII. Summary

The XBL1507B series from XBLW is a high-performance, cost-effective DC-DC converter designed for medium-voltage applications. Key features include a wide input voltage range, 3A output capability, integrated protection features, and a simple external circuit. This series offers a reliable and thermally efficient solution, helping engineers reduce development time and system costs, making it ideal for applications such as battery chargers and network equipment, as well as industrial control systems.