VDD = 3.6V okay?

RE: VDD = 3.6V okay?

Chris — Mon, 27 May 2019 10:57:45 GMT

although it's not quite clear in the specs, it seems that the difference between powering via VDDH vs VDD is in the < 10uAs... so I guess we're fine. Thanks :)

RE: VDD = 3.6V okay?

Chris — Mon, 27 May 2019 10:29:31 GMT

Thank you, Andreas. What is the impact on current draw when using VDDH vs VDD?

RE: VDD = 3.6V okay?

Andreas — Mon, 27 May 2019 07:26:46 GMT

Hi,

The inductor you mention is only needed if you want the power supply to use the 'DCDC mode', it will work without it but then in 'LDO mode'. 3.6V is the upper bound of the recommended supply range, we obviously can not recommend violating the recommended operating conditions and thus the supply range the IC has been qualified for. The absolute maximum rating is 3.9V, so it might be OK (probably not really OK) for short periods on your lab bench, but you should not go to production with it.

I suggest you take a look at our reference design config. 2, which shows supply on VDDH without any DCDC inductors, using VDD as an optional output for external circuitry. VBUS is only needed if you plan on using the USB peripheral, this is the same regardless of the power supply configuration: connect VBUS to the 5V USB voltage and hook a 4.7µF on DECUSB.

Best regards,

Andreas

RE: VDD = 3.6V okay?

Chris — Fri, 24 May 2019 13:42:42 GMT

Ah, just another idea: I could also use a Schottky (eg CDBQR0130L) which has a drop of 350mV at 10mA. But I never tried a Schottky to reduce supply voltage