TI PMP20249双路汽车12.5W USB充电器参考设计

TI公司的PMP20249是EMI优化的双路汽车12.5W USB充电器参考设计,采用LMS3635和LMS3655稳压器以及TPS2549 USB开关,具有CISPR 25 Class 4设计额定值;输入电压从6Vin到18Vin,2.5A时输出电压5V,主要用在汽车USB充电系统和汽车娱乐系统.本文介绍了参考设计PMP20249主要特性和指标,框图,电路图,材料清单和PCB设计图.
PMP20249 is an EMI-optimized design for dual-automotive USB charger system using the LMS3635 andLMS3655 regulators (400-kHz fully-integrated, synchronous buck for automotive applications) and theTPS2549 USB switch (TPS2549-Q1 automotive USB charging port controller with integrated power switchand cable compensation). The design accepts an input voltage range of 6 Vin to 18 Vin and regulates twooutputs of 5 V at 2.5 A for dual-USB ports. This highly efficient design features an inexpensive solution and small-size customized for an automotive USB charger application. A four-layer PCB was used for thisdesign.
The design is divided into four major blocks:
• Front-end protection: Front-end protection against positive and negative pulses (ISO7630 pulse 1, 2a,3a/b) through TVS.
• EMI filter: Differential filter for conducted EMI suppression.
• Low-EMI front-end DC-DC converters: LMS3655-Q1 and LMS3635-Q1 are switching, synchronous5.5-A and 3.5-A buck regulators, and in this design the devices are used as front-end DC-DCconverters. These 400-kHz parts are automotive optimized and have low EMI. The device comes in anautomotive-qualified HotRod™ QFN package with wettable flanks, which reduces parasitic inductanceand resistance while increasing efficiency, minimizing switch node ringing, and dramatically loweringEMI. The spread spectrum feature is a factory option which further reduces EMI. This featureeliminates peak emissions at specific frequencies by spreading emissions across a wider range of frequencies.
• Downstream USB charging-port controller and power switch: TPS2549-Q1 maintains 5 V at the USBport during heavy charging currents.