Buck Converter 12V-76V Input, 5V DC Output

A buck converter board has been developed utilizing the BD9G341AEFJ, a non-synchronous DC/DC converter. This board accepts a wide input voltage range of 12V to 76V DC and generates a regulated 5V DC output. The BD9G341AEFJ features an integrated 150mΩ N-channel MOSFET and a programmable switching frequency, adjustable from 50kHz to 750kHz. On this board, the switching frequency is fixed at 200kHz using resistor R5. To ensure reliable operation, the board incorporates several protection features. A fixed soft-start circuit minimizes inrush current during startup. Additionally, the board includes Under-Voltage Lockout (UVLO), Thermal Shutdown Detection (TSD), Over-Current Protection (OCP), and Over-Voltage Protection (OVP) circuits. The UVLO threshold and hysteresis are configured externally using resistors R1 and R4 connected to the EN (Enable) pin.

Features

• Input 12V to 76V DC
• Output 5V DC
• Output Current 2A, up to 3A (Read Note)
• Operating Frequency 200Khz
• On Board Power LED
• Precision EN/UVLO Threshold +/-3%
• Under Voltage Lockout (UVLO), Threshold 11V
• Soft Start Function (20mS)
• Over Current Protection (OCP)
• Thermal Shutdown (TSD)
• Over Voltage Protection (OVP)
• Screw Terminals for Power Input and Output
• PCB Dimensions 45.09 x 19.84 mm

The BD9G341AEFJ is a buck switching regulator with an integrated 150mΩ power MOSFET. Current mode architecture provides fast transient response and a simple phase compensation setup. The operating frequency is programmable from 50kHz to 750kHz. Additional protection features are included, such as Over Current Protection, Thermal shutdown,n and Under voltage lockout.  The under-voltage lockout and hysteresis can be set by an external resistor.

UVLO

This is a Low Voltage Error Prevention Circuit. This prevents internal circuit error during increase of Power Supply Voltage and during decline of Power supply Voltage. It monitors VCC Pin Voltage and internal REG Voltage, When VCC Voltage becomes 11V and below, UVLO turns OFF all Output FET and turns OFF the DC/DC Comparator Output, and the Soft Start Circuit resets. Now this Threshold has Hysteresis of 200mV.

OSC

This block generates inner CLK. The internal oscillator is set with a single resistor connected between this pin and the GND. RT pin connects to 47kohm, frequency is set 200 kHz.

EN Shutdown function.

If the voltage of this pin is below 1.3V, the regulator will be in a low power state. If the voltage of this pin is between 1.3V and 2.4V will be standby mode. If the voltage of this pin is above 2.6V, the regulator is operational. An external voltage divider resistor R1 and R4 used to set under voltage threshold.

OCP Over current protection

If the current of power MOSFET is over 6.0A (typ), this function reduces duty pulse –by- pulse and restricts the over current. If IC detects OCP 2 times sequentially, the device will stop and after 20 msec restart.

TSD (Thermal Shutdown)

This is Thermal Shutdown Detection When it detects an abnormal temperature exceeding Maximum Junction Temperature (Tj=150°C), it turns OFF all Output FETs, and turns OFF the DC/DC Comparator Output. When Temperature falls, and the IC automatically returns

OVP Over voltage protection

Output voltage is monitored with FB terminal, and output FET is turned off when it becomes 120% of set-point voltage.

Connections

• CN1: Pin 1 = + DC Input 12V-76VDC, Pin 2 = GND
• CN2: Pin 1 = +5V DC Output, Pin 2 = GND
• D1: Power LED

Schematic

Parts List

Connections

Gerber View

Photos

Video

BD9G341AEFJ Datasheet