RT4813A Single Li-ion Cell High Efficiency Boost Converter
Created: Feb 01, 2017
No description available.
Wearable devices and other portable equipment are now usually powered by a lithium-ion battery. Lithium-ion batteries come in a small size and are lightly built. Majority of lithium-ion batteries have a voltage rating of 3.7V and can really supply a lot of energy. However, portable devices usually operate with 5V power supply. In this case, a DC-to-DC converter is used to convert the voltage level of the lithium-ion battery to the required operating voltage of the device.
This reference design features a small but highly efficient boost converter. The RT4813A can boost the voltage from a single-cell lithium-ion battery up to 96% efficiency. It can boost up to 5.5V and can output current up to 3.25A. The RT4813A device also has overcurrent and overvoltage protection both for input and output. The schematic shown in this reference design is a typical application circuit of the RT4813A DC-to-DC converter. C1, C2, and L1 are connected between the high-side and low-side switches of RT4813A. The capacitors (C1-C2) improve output voltage ripple while the inductor (L1) filters the current. C3 serves as an input capacitor to the power input (VIN) of the device. The resistance of R1 and R2 determines the output voltage level. With the value of R1 and R2 in this design, the expected output voltage of the device is approximately 5V. C4 and C5 are used as a filter the output voltage of the RT4813A.
The header J2 in this design extends the enable (EN) and I2C (SDA and SCL) pins of RT4813A. The EN pin can be used to enable (pull to HIGH) or disable (pull to LOW) the device while I2C pins can be used to set device configurations like current limit, switching frequency, etc. The lithium-ion battery can be connected to header J1 or JST connector (JST1). The output of the device is connected to header J3 and screw terminal ST1. This design can be integrated in a system that requires 5V power supply but is powered with a single-cell lithium-ion battery.