High Current Half-Bridge with Over Current & Voltage Feedback for Step Down DC-DC Converter

This project enables the user to create a high current DC-DC converter. The project consists of a high current inductor, high current low voltage 2 x MOSFETs, half-bridge driver LT1158 chip, voltage feedback using onboard R9 and R10 resistor dividers, shunt resistor for overcurrent shut-down. The project has all the required components to create a high current step-down DC-DC converter, refer to the datasheet of LT1158 chip for components selection. The Half-bridge requires a PWM input signal, Arduino or another microcontroller/DSP can be used as a host to generate PWM signal and control enable and fault conditions.

Arduino Example Code helps users to test the board, the project provides output approx. 5V/4Amps from input Supply 22-24V DC.

Applications

• DC-DC Converter
• High Current Solar Charger
• SLA Battery Charger

Key Features

• High Current Low Voltage 2 x MOSFET IRF540 (the user may Use Other Low Ohm MOSFET)
• Half-Bridge Driver LT1158 Chip
• L1 High Current Inductor Default 100uH/7.8Amp
• R2 and R3 Resistor for Current Sense, For Over Current Limit/Short Circuit – Refer to Datasheet for R2, R3 Values.
• Fault: Open collector NPN output which turns on when V12 – V11 (Current Sense Pins) exceeds the fault conduction threshold.
• D3 LED for Output, D2 LED for Input Supply
• Voltage Feedback Output CN5, Resistor Divider R9, R10, C11
• Inputs and Fault Output CN2
• Operating Supply 12V to 30V DC (Input Supply Should Not Exceed 30V)
• PCB Dimensions 69.22 x 55.88 mm

Over Current Shutdown – Open collector, NPN output turns on when V12 – V11 (Current Sense Pins) exceeds the fault conduction threshold.

• For Internal Over Current Shutdown Use R7 and C8, Refer to Datasheet for Values
• For Host Controlled Shutdown Use Fault and Enable Pins

Voltage Feedback

• CN5, Feedback from Output using Resistor Divider R9 and R10, Use C11 for stability.

Connections: CN2

• Pin1 = VCC
• Pin2 = Enable – Pull Low to disable the Output
• Pin3= Fault Output – Goes Low when Over Current Condition Occurs
• Pin4= PWM Input 0 to 100Khz
• Pin5=GND
• Use R7 and C8 for Internal Over Current Shutdown, Refer to Datasheet of LT1158

Connections CN1

• Pin1 = VCC 12V to 30V Input
• Pin2 + GND

Connections CN3

• Pin1 = + Output
• Pin2= GND

CN4: Not Installed

Connections CN5

• Pin 1 = +Voltage Feedback Output
• Pin 2 = GND

Schematic

Parts List

Connections

Gerber View

Photos

Video

LT1158 Datasheet

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