Compact DC-DC Converter with Input 24V and [email protected] Output

We are introducing a compact DC-DC converter that delivers a 5V output with a load current of up to 1.5A, powered by an input supply of 24V to 26V DC. This innovative project boasts key features such as soft start, thermal shutdown, and overcurrent protection. Built using the MP2345 TSOT23-6 DC-DC Converter, this mini board offers a significant advantage over traditional LDOs like LM7805, occupying a much smaller area while providing more power and generating minimal heat.

Features

• Supply 24V-26V
• Output 5V DC
• Load Current 1.5A
• 3 Pin Header Connector for Input and Output (GND Common)
• Internal Power-Save Mode for Light Load
• 600Khz Fixed Switching Frequency at CCM
• Internal Soft Start
• Over Current Protection (OCP) and Hiccup Mode
• Thermal Shutdown
• PCB Dimensions 17.78 x 10.64 mm

The MP2345 is a high-efficiency, synchronous, rectified, step-down, switch-mode converter with built-in internal power MOSFETs. It offers a very compact solution that achieves 2.5A of continuous output current with excellent load and line regulation over a wide input supply range. The MP2345’s switching edge is optimized for low EMI. SW anti-ringing is employed to address high-frequency radiation EMI issues. Full protection features include over-current protection (OCP) and thermal shutdown.

Internal Soft Start (SS)

Soft start (SS) is implemented to prevent the converter output voltage from overshooting during start-up. When the chip starts up, the internal circuitry generates a soft-start voltage that ramps up from 0V. The soft-start period lasts until the voltage on the soft-start capacitor exceeds the 0.791V reference voltage. At this point, the reference voltage takes over. The soft-start time is set internally to be about 1.5ms from 10% to 90% of VOUT.

Over-Current Protection (OCP) and Hiccup Mode

The MP2345 employs a cycle-by-cycle over current limit when the inductor current peak value exceeds the set current-limit threshold.  Meanwhile, the output voltage drops until FB is below the under-voltage (UV) threshold, typically 50% below the reference. Once UV is triggered, the MP2345 enters hiccup mode to restart the part periodically. This protection mode is especially useful when the output dead-shorts to ground. The average short circuit current is greatly reduced to alleviate

Thermal Shutdown

Thermal shutdown prevents the chip from operating at exceedingly high temperatures. When the silicon die temperature is higher than 150°C, the entire chip shuts down. When the temperature is below its lower threshold (typically 130°C), the chip is enabled again.

Circuit Start-Up and Shutdown

If VIN is higher than its UVLO threshold, the chip starts up. The reference block starts first, generating a stable reference voltage and current, and then the internal regulator is enabled. The regulator provides a stable supply for the remaining circuitries. In the shutdown procedure, the signaling path is first blocked to prevent any fault triggering. VCOMP and the internal supply rail are then pulled down. driver is not subject to this shutdown command.

Connections

• CN1: Pin 1 = VIN 24V to 26V, Pin 2 = GND, Pin 3 = 5V DC Output

Schematic

Parts List

Connections

Gerber View

Photos

MP2345 Datasheet

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