| ??? 06/02/08 12:56 Read: times |
#155395 - What you CAN do Responding to: ???'s previous message |
Alex Chiu said:
I would like to design good products, however, nowadays, products are need to be interfaced or integrated to others. For example, you design a mobile phone market the mobile. However, most often, you do not design the charger, you OEM or you simple let the client buy the charger. My products is like that, I cannot provide the power supply as the client provides that. I cannot control where my client install the equipment. My experience, when they installed in peak, lightning surge always damage the products. So, I simple thank a chip that features watch dog and monitor the power is the easy way. At the end, does anyone have idea on a chip have that function : AT89C55WD + CL1232 Regards Alex This might apply if the watchdog were, in any way, capable of solving the problems that cause it to become active. It is not! Though you don't provide the raw power supply, you can do what is necessary to filter and regulate your on-board supply properly. If you specify the raw, external supply properly, your customer will have to provide it, isn't that so? You must ensure that you have sufficient headroom on the input supply so that you can do whatever is necessary in order to protect the on-board power from outside stress. You must provide the necessary filters, MOV's, clamps, etc, to limit the input supply's effect on the regulated VCC and GND rails. You must provide the firmware that will recover from any and all "normal" (lightning, brownout, stupid user, etc.) stresses. You must provide the means by which your firmware will "know" what happened. You must provide firmware that will, under no circumstances, wander off into the tall grass. The watchdog can't do any of that. All it can do is tell you that trouble has arrived. It's like the light on the dashboad of your car ... the one that says "check engine". It simply tells you that trouble has arrived, and not what sort of trouble it is. RE |
