Multi Output Step-Down Converter – Input 18-24V and Output 3.3V, 5V, 12V

  • Rajkumar Sharma
  • 54 Views
  • moderate
  • Tested
  • SKU: EL154163
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This is a fantastic project for makers, offering multiple output options of 3.3V, 5V, and 12V, with an input of 18-24V DC. This project is built around the MP2451 high-frequency (2Mhz) step-down switching regulator, ensuring efficient and reliable power conversion. For added convenience, a header connector is provided for outputs and input supply, while a power LED indicator ensures easy power status monitoring. This project is particularly well-suited for low-current applications, and its compact PCB design occupies a minimal footprint, making it ideal for space-constrained projects.

The output voltages of the three channels are set to 3.3V, 5V, and 12V using the following resistor combinations:

  • 3V: R1 + R3
  • 5V: R2 + R4
  • 12V: R9 + R11

Users can modify the feedback divider resistor values to adjust the output voltages to meet their specific requirements. The output voltage range is adjustable from +0.8V to 0.8 x VIn. For the divider resistor formula, refer to the chip’s datasheet.

Features

  • Input 18-24V DC
  • Outputs 3.3V, 5V, 12V, Load Current 300mA Each (max 600mA per channel)
  • On Board Power LED
  • Header Connector for Outputs and Input
  • 2MHz fixed Switching Frequency
  • Internal Soft-Start
  • Precision Current Limit Without Current Sensing Resistor
  • Thermal shutdown
  • PCB Dimensions 32.07 x 19.37 mm

The MP2451 is a high frequency (2MHz) step-down switching regulator with integrated internal high-side high voltage power MOSFET. It provides a single 0.6A (or less) highly efficient output with current mode control for fast loop response. The wide 3.3V to 36V input range accommodates a variety of step-down applications in the automotive input environment. A 3μA shutdown mode quiescent current allows use in battery-powered applications. High power conversion efficiency over a wide load range is achieved by scaling down the switching frequency at light load conditions to reduce the switching and gate-driving losses. Frequency fold-back helps prevent inductor current runaway during start-up. Thermal shutdown provides reliable, fault-tolerant operation.

Connections

  • CN1: Pin 1 = DC Input 18V to 24V, Pin 2 = GND, Pin 3 = GND, Pin 4 = 3.3V, Pin 5 = 5V, Pin 6 = 12V
  • D7: Power LED (Input)

Schematic

Parts List

N0.QNTY.REF.DESC.MANUFACTURERSUPPLIER SUPPLIER PART NO
11CN16 PIN MALE HEADER PITCH 2.54MM RIGHT ANGLEWURTHDIGIKEY732-5319-ND
23C1,C2,C9100nF/50V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
33C3,C5,C1010uF/16V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
42C4,C633PF/50V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
53C7,C8,C1210uF/35V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
61C1147PF/50V CERAMIC SMD SIZE 0805YAGEO/MURATADIGIKEY
76D1,D2,D3,D4,D5,D6ES1BL R3GTAIWAN SEMIDIGIKEY1801-ES1BLCT-ND
81D7LED RED SMD SIZE 0805OSRAMDIGIKEY475-1278-1-ND
92L1,L24.7uH/2A - 3.7X3.9MMMURATADIGIKEY490-14184-1-ND
101L36.8uH/1.9A - 3.5MMX3.2MMBOURNS INCDIGIKEYSRP3020TA-6R8MCT-ND
111R186.6K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
121R2130K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
131R327.4K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
141R424K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
153R5,R7,R12470K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
163R6,R8,R13110K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
171R991K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
181R104.7K 5% SMD SIZE 0805YAGEO/MURATADIGIKEY
191R116.49K 1% SMD SIZE 0805YAGEO/MURATADIGIKEY
203U1,U2,U3MP2451 SOT23-6MPSDIGIKEY1589-1893-1-ND

Connections

 

Gerber View

Photos

Video

MP2451 Datasheet

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