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(1) Let VDD voltage higher than common appliance, when USB works http://www.infobluetooth.com TEL:+86-23-68798999 Fax: +86-23-68889515 Page 4 of 10
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11 Check List SCH Function voltage of the module power is 2.7 to 3.6V. so the RS232 chipset needs to be transfer is also applied to this voltage bound. This typical component is MAX3232. but we should pay a attention on MAX3232 function baud rate, which is 120kbps. pic adopt stable voltage chipset, the highest voltage is 12V.SCH. obviously, module should be broken if beyond this bound. This chipset fall into lower-voltage chipset, we suggest adopting external power in the range of 5± 0.25v. From above USB power supply list, we can get once we use USB, the best way is trying to let module work on the range of 3.3± 0.1 V. 11.2 PCB Check List antenna part(rf part) is close to device edge to the greatest extent, there must be without any metal obstruct between the direction of antenna energy radiate and outside. Check more details in 10 Chip dielectric antenna position and feed point position? the bottom of module touch PCB. in order to eliminate capable short circuit, try to use insulation material separating two side of metal in setting module part. Simple way, place a holistic silk-screen here. considering about integer beauty impression on the base of compliance to electric product and mechanism configuration requirement, component setting must be equilibria and density in order on PCB. PCB dimension must be similar to machining drawing, and accord with PCB manufacturing craftwork request. try to make sure there isn t any conflict in two dimension space or three dimension when we set MARK point here. component need replacing frequently ask for convenient insert board. UART with direction adopt dissymmetric UART mark. though current module we use right now isn t hot-sensitive component, we also need proper distance between two components. setting line must have logical direction. For example, input/ output, AC/DC, strong/weak singal, high/ low frequency, high/ low voltage and so on, their direction should be a line (or separated) not mingle with another, in order to avoid disturbing each other. The best setting direction is compliant to line, but it is hard to realize. logically set power strain wave/capacitance. Try to be close to these components in setting capacitance. If the distance is too far it can t function well. http://www.infobluetooth.com TEL:+86-23-68798999 Fax: +86-23-68889515 Page 9 of 10
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