How to implement a 5V 90W USB-C automotive charging ports with LITIX POWER FLEX TLD5501-2QV
A buck controller is the perfect selection to generate the 5V output voltage from the 12V battery line. The total amount of power is 90 W (5 V, 18A) so a synchronous buck DC-DC would help to improve the system efficiency. Moreover, due to the relative high current output demand of up to 18 A, a multiphase buck DC-DC controller would be the perfect choice in order to split the output current between two inductors and then relax the requirements for the inductors and the switching elements.
Indeed a multiphase design allows significant flexibility for output inductor choice, which is extremely important in small form factor applications because it allows to select a device with a smaller saturation current with the consequence that smaller inductor sizes can be selected.
Another benefit of the multiphase design is to reduce the output voltage ripple by a factor n, where n is the number of phases, without the need to increase the output filter capacitance.
Moreover a multiphase design improves also the EMC performances of the DC-DC with the consequence that BOM cost can be saved by designing smaller filters.
Infineon offers the right choice for a buck multiphase voltage regulator: the TLD5501-2QV.
TLD5501-2QV is a dual channel synchronous buck DC-DC controller explicitly designed for high power applications. The two channels can work independently or in multiphase operations. It implements an SPI interface to control and retrieve the status of the DC-DC. The switching frequency is adjustable in the range of 200 kHz to 700 kHz. It can be synchronized to an external clock source. A built in programmable Spread Spectrum switching frequency modulation and the forced continuous current regulation mode improve the overall EMC
behavior. Furthermore, the current mode regulation scheme provides a stable regulation loop maintained by small external compensation components. The adjustable soft start feature limits the current peak as well as voltage overshoot at start-up.
The control unit hardware implementation with the TLD5501-2QV is then shown in Figure 1.
In Figure 2 the application diagram of the TLD5501-2QV as voltage supply in multiphase operation is shown
Figure 1: Automotive USB-C system hardware implementations with TLD5501-2QV
Figure 2: Application diagram of TLD5501-2QV as buck voltage regulator in multiphase operation
For further information check the TLD5501-2QVdatasheet, while more information on how to design a proper solution can be found in the application note Infineon-Z8F67775974_USB-C_automotive_charging_ports_with_LITIXTM-ApplicationNotes-v01_00-EN.pdf