Low-Cost Boost Converter 3.3V Input – 5V Output at 250mA

Mini Isolated Power Supply is designed for CAN, RS-485, RS-422, RS-232, SPI, I2C, Low-Power LAN applications. The power supply provides +/- 5.50 V DC symmetrical outputs with load current 500mA from 5V DC input. The project is built using SN6505A IC from Texas instruments. The SN6505A is a low-noise, low-EMI push-pull transformer driver, specifically designed for small form factor, isolated power supplies. It drives low profile, center-tapped transformers 5 V DC power supply. Ultra-low noise and EMI are achieved by slew rate control of the output switch voltage and through Spread Spectrum Clocking (SSC). The SN6505 consists of an oscillator followed by a gate drive circuit that provides the complementary output signals to drive ground referenced N-channel power switches. The device includes two 1-A Power-MOSFET switches to ensure start-up under heavy loads. The internal protection features include a 1.7A current limiting, under-voltage lockout, thermal shutdown, and break-before-make circuitry. SN6505 includes a soft-start feature that prevents high inrush current during power up with large load capacitors.

This is a versatile tiny module that provides 10V/500mA from 90V DC input. It is a high voltage input DC-DC buck converter, based on LM5017 IC, which is a 100-V, 600-mA synchronous step-down regulator with integrated high side and low side MOSFETs. The constant on-time (COT) control scheme employed in the LM5017 requires no loop compensation, provides an excellent transient response, and enables very high step-down ratios. The ON-time varies inversely with the input voltage resulting in nearly constant frequency over the input voltage range. A high voltage startup regulator provides bias power for the internal operation of the IC and for integrated gate drivers. A peak current limit circuit protects against overload conditions. The under-voltage lockout (UVLO) circuit allows the input under-voltage threshold and hysteresis to be independently programmed. Other protection features include thermal shutdown and bias supply under-voltage lockout (VCC UVLO). Supply input range 13V to 90V, provides 10V/500mA, switching frequency 225 KHz. Adjustable output voltage possible by altering Resistor R6 and R8 value, refer data sheet. Under-Voltage lockout set to 12.4V.

The project presented here is capable of supplying 400mA of current from a 3.7V Li-Ion/Li-Po Battery input with a 5V output. The converter has an internal soft start and internal frequency compensation features. The project is built using LTC3426 SOT23-6 chip. The LTC3426 chip is in a low profile (1mm) SOT-23 package and has a very low shutdown current of about 0.5µA. A switching frequency of 1.2MHz allows a tiny solution. The tiny PCB can be mounted on the backside of the a 18650 battery holder. Jumper J1 is the shut-down jumper. Internal soft-start eases inrush current issues.

This tiny power module is an easy-to-use integrated power solution that combines a 3A DC/DC converter chip with inbuilt power MOSFETs, an inductor, and passives into a 3-pin, through-hole package. The standard TO-220 pin-out allows a much-improved replacement of linear regulators packaged in this industry-standard footprint. The circuit provides much higher efficiency and output current without the need for a heatsink. This is an easy replacement of the LM7805 linear regulator with higher input voltage and output current than LM7805. Operating supply 8-28V DC, output 5V DC at 1A. The project is built using the TPS54302 chip from Texas instruments.

This is a multiple output power converter module that provides +/-10V (Dual 10V), 5V DC, and 3.3V DC from a 9V PP3 battery. This is a very useful project that has been designed for low-load current applications. Dual +/-10V output from a 9V battery is a key feature of the project. The battery holder can be mounted on the backside of the PCB. An onboard slide switch provides power ON/OFF. Onboard LED indicates the power. LM1117-5V chip provides 5V DC output from 9V Battery, further, an LM1117-3.3V regulator is provided to step down the 5V to 3.3V DC. MAX680 charge pump chip provides +/-10V from 5V.