help about vpp
huangshangjian
Posts: 1
Hello!
In the diagram show at below. The SX key need·a vpp 12.5V, but you know, the·COM on PC have no provide this voltage. So, can you tell me how can i deal with this voltage? And can you show me the actual voltage·on the pin ocs1 please? 5v or 12.3 or not? More detail show at the attachment file.
Thank you very much!
Post Edited (huangshangjian) : 8/19/2004 6:59:04 AM GMT
In the diagram show at below. The SX key need·a vpp 12.5V, but you know, the·COM on PC have no provide this voltage. So, can you tell me how can i deal with this voltage? And can you show me the actual voltage·on the pin ocs1 please? 5v or 12.3 or not? More detail show at the attachment file.
Thank you very much!
Post Edited (huangshangjian) : 8/19/2004 6:59:04 AM GMT
pdf
142K
Comments
Some real experts will confirm if this is correct or not.
But the reason I believe the SX key generates the 12 volts is that I do not connect any external 12 volts to the system when programming. I only connect regulated 5v to the SX, and the SX key to the computer serial port.
Ken
if you look at the SX-Key, you will notice a part looking like a coil, located close to the DB-9 jack. I'm pretty sure that this is part of the "on-board" voltage converter which generates Vpp, although I don't have the SK-Key schematic here.
It is definitely not taken from the COM port as it could not supply enough current.
Greetings,
G