TPS61046: PWM/PFM current swith point treshold

Hi Berty
depend on the inductor you select. if using 10uH inductor, the device should be always at PFM.
please refer to description in the datasheet, the device enter PFM when the peak current reduce to 140mA.

how PFM or DCM impact your application?

Hi Jasper, thanks for replying. the data sheet does not mention the range of the PFM frequency and I afraid it will go down from 1MHz to the same frequency our system is working and could affect our performance. i would like to verify that the boost will stay on PWM mode. i'm using 4.7uHy, 3V-> 12V, outpot load between 1mA to 5mA
thanks.
Berty

in the light load 1mA for example, the device will enter PFM mode. to avoid enter PFM, you need to add load until the inductor peak current is higher than typical 140mA (200mA considering the worst condition). so you need to keep the load higher than 10mA at 3V ->12V to avoid PFM.

Hi Jasper, OK, i got two more questions:

1. is it OK to increase the inductor to 10uF in order to get to the 140mA instead make the load bigger?

2. what about the PFM question? how can i know / calculate the PFM frequency? as i said before we are afraid that the boost freq will be on our system freq and we afraid from interference.

thanks.

Berty.

1. using 10uH or higher inductor, we need to add larger load to avoid entering PFM mode. smaller inductance than 4.7uH also cause larger load to enter PWM mode.
2. we don't have a formula to calculate the frequency of PFM.