Other Parts Discussed in Thread: UCC27282-Q1
Tool/software:
Wireless charging for mobile devices in automobiles is a common and convenient feature. These chargers are typically powered from the 12V battery system but in some cases could utilize a 48V battery. The basic functions are the same as a desk top charging pad and are shown below.
Figure 1
The basic functions in the transmitter are the control, communication and power stage driving the transmitter coil. In the receiver side there is the receiving pick up coil, control for battery charging and communication. We will concentrate on the transmitter side and the gate driver solutions well suited for this function.
There are mainly two charging standards in the market: Qi inductive and magnetic resonance. The most dominant is Qi inductive which can utilize one transmit coil, or multiple transmit coils with a multiplexer, and operates at 100kHz to 300kHz. The magnetic resonance solution operates at 6.78MHz with a single coil. The Qi inductive approach is dominant in the marketplace as the lower switching frequencies result in a more cost effective solution, and is the focus of this FAQ.
A common configuration in the transmitter’s coil driver is to drive the transmit coil with a full bridge configuration powered by the 12V car battery. The UCC272xx family is shown in the transmitter diagram below.
Figure 2: Transmitter Block Diagram
TI has an extensive portfolio of 100V half-bridge drivers that are good candidates for the transmitter side of wireless charging systems using the Qi inductive standard. The UCC27201A-Q1, UCC27212A-Q1, UCC27311A-Q1, and UCC27211A-Q1 have high drive strength, low propagation delay and low delay matching which are important parameters for high frequency operation. The UCC27301A-Q1 and UCC27282-Q1 also add input interlock which prevents the driver outputs from being high at the same time if both driver inputs are high. This feature will enhance the robustness and noise immunity of the wireless charging power system. The UCC27212-Q1 and UCC27282-Q1 have lower UVLO thresholds which allow for VDD operation at 6V to 6.5V
For the input voltage systems limited to 20V, the TPS28225-Q1 is a good candidate which has a single PWM input with complimentary high side and low side gate drive of +/-2A and internal dead time.
For the magnetic resonance standard, we recommend looking into the GaN half-bridge drivers that TI offers such as the LMG1205, LMG1210 and LM5113-Q1 since the switching frequency of this standard is 6.78MHz and the GaN drivers can support 3-30MHz or higher operation. The GaN drivers feature low propagation delays of 10ns to 28ns and delay matching of 1ns to 1.5ns typical which is important for very high frequency operation.