The capacitors C1 and C2 are used as filtering capacitor for removing unwanted voltage spikes and ripples from the supply line. The diode D1, capacitors C3 and C4 are part of the bootstrap circuit (as shown in the figure below). In this circuit, SD, Vss, and COM pins are all connected to the ground (as shown in the circuit diagram). By connecting it to ground the chip has been enabled. The SD pin is for shut down or to turn OFF the IC. Both are not internally connected to each other so they have been connected separately with the ground. The Vss is the logic ground and COM is the low side return. As the microcontroller is used for giving input signals to Lin and Hin pins and the controller works on TTL logic, VDD equal to 5V is used to avoid any undermine state at the output due to mismatching in VDD and logic input power supply. This IC works on TTL or CMOS logic so for input greater than 3V it will give logic 1. If the Hin pin is low this turns OFF the high side driver and output at HO is equal to Vs. Similarly, when the input at Hin is high then this drives the high side driver and output at HO is equal to VB. If the Lin pin is low this turns OFF the low side driver and output at LO is equal to COM (ground). When the input at Lin is high then this drives the low side driver and output at LO is equal to VCC. The Lin and Hin pins are the input logic supply pins for driving the low or high side driver. The actual voltage of VDD is decided by the input supply of Lin and Hin pin. The VDD should range in between 3 V to 20 V (with reference to Vss). The VDD is the logic voltage for working of the internal circuitry of the IC. The VCC is the low side voltage and should be in range from 10 V to 20 V. So, this IC suits best as per the requirement of the circuit. This IC drives the high side MOSFET using the external bootstrap circuit as well as the low side MOSFET (which do not require any external circuit). So for full bridge configuration, there needs two IR2110 ICs. This IC can drive a half bridge circuit one at a time. Plus it can be easily used in any circuit. In the circuit designed here, IR-2110 IC is used. That extra circuit can be incorporated by using some IC having the circuit inbuilt or by designing the circuit explicitly. But the MOSFET cannot be driven with only bootstrap circuit. In circuit designed here, bootstrap method is used to drive to the high side MOSFET. As high side MOSFET cannot be normally operated like low side MOSFETs, there are two methods of driving the high side MOSFET – one is through “dual power supply” and another is by using “bootstrap circuit”. So, it is first important to understand the half bridge circuit and its driving method. The full bridge configuration is the combination of two half bridge circuits.
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