TI公司的PMP20249是EMI優化的雙路汽車12.5W USB充電器參考設計,采用LMS3635和LMS3655穩壓器以及TPS2549 USB開關,具有CISPR 25 Class 4設計額定值;輸入電壓從6Vin到18Vin,2.5A時輸出電壓5V,主要用在汽車USB充電系統和汽車娛樂系統.本文介紹了參考設計PMP20249主要特性和指標,框圖,電路圖,材料清單和PCB設計圖.

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.

參考設計PMP20249主要特性:

? Wide-Vin Front-End Power Supply for USBCharger System
? Off-Battery Operation With Positive and NegativeOvervoltage Protection
? Passed CISPR 25 Class 4 Conducted EMI Test
? Switching Frequency: Outside AM Band (400 kHz)for all Converters
? All AEC-Q100-Qualified Devices
? Supports 6-V to 18-V Wide-Vin Range

參考設計PMP20249應用:

? Automotive USB Charger System
? Automotive Infotainment System

圖1.參考設計PMP20249外形圖
參考設計PMP20249主要指標:

圖2.參考設計PMP20249框圖

圖3.參考設計PMP20249電路圖
參考設計PMP20249材料清單:

圖4.參考設計PMP20249 PCB設計圖(1)

圖5.參考設計PMP20249 PCB設計圖(2)

圖6.參考設計PMP20249 PCB設計圖(3)

圖7.參考設計PMP20249 PCB設計圖(4)

圖8.參考設計PMP20249 PCB設計圖(5)

圖9.參考設計PMP20249 PCB設計圖(6)

圖10.參考設計PMP20249 PCB設計圖(7)

圖11.參考設計PMP20249 PCB設計圖(8)

圖12.參考設計PMP20249 PCB設計圖(9)

圖13.參考設計PMP20249 PCB設計圖(10)
?