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Using a C932. In sleep mode we ought to be at about 2uA - instead we sit at 25uA. This is with the part with I/O lines in the air, external xtal, VCC and ground. We have done everything in the book, but still this high power drain, making the chip useless in a battery application. Anybody out there see anything close to book power in sleep mode? Thanks!
Using a C932. In sleep mode we ought to be at about 2uA - instead we sit at 25uA. This is with the part with I/O lines in the air, external xtal I do not know what a C932 is, but the LPC932 need internal oscillator to really go low in sleep. Erik
Thanks Erik We have actually gone so far as to run the 932 in a socket, to be sure our PCB was not the cause of the problem. Where we should be burning 2uA ro 4uA we get consistant 24uA Did try running on the internal clock - which the book suggests would actually be a higher current - no difference. What is the lowest power down current you have seen? Thanks, R
I have never powerdowned (sorry) a LPC932, just repeated some info someone gave me sometime. Erik
So you take the part out of the socket, and the measured current is 0uA ? or 24uA less ?
Here was the problem and solution: "Without any programming changes the WDT oscillator will continue to run during power down, consuming approx. 50 mA. To prevent this from happening, the user software has to switch the clock source for the WDT to PCLK. This can be done by clearing the bit WDCLK in register WDTCON followed by a feed sequence. With PCLK selected as source for the WDT, the WDT oscillator will go into power down together with the rest of the chip." http://www.lpc900.com/pdf/single-battery.pdf Note we had the WD off, but without this change it was still doing something. THANK YOU LPC900.com !!!!!!