In this tutorial, we are going to make an “LTC3442 Buck Boost Converter Circuit”.
A buck-boost converter is a DC-DC converter with an output voltage that can be higher or lower than the input voltage. The buck-boost converter is similar to the flyback converter, except instead of a transformer, it uses a single inductor. There are two types of converters in the buck-boost converter that are buck converter and the other one is a boost converter. These converters have a wide output voltage range, ranging from a voltage substantially higher than the output voltage to a voltage near zero. Here we design a buck-boost converter circuit based on LTC3442 to give 3.3V at maximum current rating from li-ion battery input. LTC3442 is a micropower synchronous buck-boost DC/DC converter Integrated circuit with automatic burst mode operation and it can drive the output voltage and current above or below the input voltage and current, it has an input voltage range between 2.4V to 5.5V and output voltage range between 2.4V to 5.25V and this IC comes in small DFN package. It provides efficient, well-regulated 3.3V output power at currents up to 1.2A with very low ripple, even as the battery voltage varies from 4.2V down to less than 3V. The automatic Burst Mode feature enables it to maintain high efficiency, even as the load becomes very light.
Hardware Components
The following components are required to make Buck Boost Converter Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | IC | LTC3442 | 1 |
| 2. | Resistor | 1MΩ, 75KΩ, 15KΩ, 340KΩ, 2.2KΩ,200KΩ | 1,1,1,1,1,2 |
| 3. | Electrolyte Capacitor | 10µF, 22µF | 1, 1 |
| 4. | Inductor | 4.7µH | 1 |
| 5. | Ceramic capacitor | 470pF, 220pF, 0.01µF | 1, 1, 2 |
| 6. | Li-ion Battery | 3.7V | 1 |
LTC3442 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LTC3442
Buck Boost Converter Circuit
Working Explanation
In this circuit we have used 0805 (imperial code) size SMD components, the IC LTC3442 provides four different automatic operations and gives high-efficiency output. The output duty cycle of the switches determines by the internal error amp output voltage on VC. this circuit maintains the output at 3.3V and it may be above or below the input voltage. Automatic burst mode operation allows the converter to change operating modes as the load current varies, maintaining high efficiency, without any commands required from a host. This buck-boost converter IC utilizes <1μA Shutdown current only and for quiescent 35 μA. With an external resistor operating frequency and average input current limit can each be programmed. Other features of LTC3442 like soft-start, peak current limit, and thermal shutdown are also programmable. This converter maintains regulation during load transients, when the battery ESR may cause the input voltage to drop below 3.3V momentarily.
Applications
This is ideal for applications such as miniature disk drives in portable devices, can be used in USB peripherals, low voltage medium current servos, handheld instruments, high power LED drivers, etc.,
