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. | MANUFACTURER | SUPPLIER | SUPPLIER PART NO |
---|---|---|---|---|---|---|
1 | 1 | CN1 | 6 PIN MALE HEADER PITCH 2.54MM RIGHT ANGLE | WURTH | DIGIKEY | 732-5319-ND |
2 | 3 | C1,C2,C9 | 100nF/50V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
3 | 3 | C3,C5,C10 | 10uF/16V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
4 | 2 | C4,C6 | 33PF/50V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
5 | 3 | C7,C8,C12 | 10uF/35V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
6 | 1 | C11 | 47PF/50V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
7 | 6 | D1,D2,D3,D4,D5,D6 | ES1BL R3G | TAIWAN SEMI | DIGIKEY | 1801-ES1BLCT-ND |
8 | 1 | D7 | LED RED SMD SIZE 0805 | OSRAM | DIGIKEY | 475-1278-1-ND |
9 | 2 | L1,L2 | 4.7uH/2A - 3.7X3.9MM | MURATA | DIGIKEY | 490-14184-1-ND |
10 | 1 | L3 | 6.8uH/1.9A - 3.5MMX3.2MM | BOURNS INC | DIGIKEY | SRP3020TA-6R8MCT-ND |
11 | 1 | R1 | 86.6K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
12 | 1 | R2 | 130K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
13 | 1 | R3 | 27.4K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
14 | 1 | R4 | 24K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
15 | 3 | R5,R7,R12 | 470K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
16 | 3 | R6,R8,R13 | 110K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
17 | 1 | R9 | 91K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
18 | 1 | R10 | 4.7K 5% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
19 | 1 | R11 | 6.49K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
20 | 3 | U1,U2,U3 | MP2451 SOT23-6 | MPS | DIGIKEY | 1589-1893-1-ND |
Connections