replace watchdog oscillator with ext osc

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by tbelo on Sat Dec 13 03:42:29 MST 2014
Trimming my prototype board with the "timed wakeup" application scenario had pretty good wakeup times.
Testing the same code with the production boards I realize the in each board the wakeup time varies unacceptable for the application.

Since I haven't used any external oscillator can I attach an external one to replace watchdog oscillator for the deep sleep timing ?
And if yes with what characteristics for my low power application?
I use lpc1115.

I see that in user manual manual but just wondering if I can save the project somehow: Power configuration in Deep-sleep mode
Power consumption in Deep-sleep mode is determined by the Deep-sleep power
configuration setting in the PDSLEEPCFG (Table 41) register:
The only clock source available in Deep-sleep mode is the watchdog oscillator. The
watchdog oscillator can be left running in Deep-sleep mode if required for
timer-controlled wake-up (see Section 3.10.3). All other clock sources (the IRC and
system oscillator) and the system PLL are shut down. The watchdog oscillator analog
output frequency must be set to the lowest value of its analog clock output (bits
FREQSEL in the WDTOSCCTRL = 0001, see Table 13).

Best regards