PF3000 unused outputs

[demoniacmilk]

Hello community,

I am using the PF3000 as the primary PMIC to power my MX7 based hardware.

For the first demo version of the board the 5V output was used for testing purposes, but it is not needed any longer.

May I cut some of the parts connected to the boost regulator? (Diode+Caps+Inductor ~ 50ct cost per device)

Or does the circuit need to be connected? In this case I could probably lower the capacitance values (currently 2x22uF+100nF+4.7uF).

Some LDOs are not used as well, simply using a small capacitor here should be the best option?

Regards,
Lars

[reyes · Accepted solution]

Hi Lars,

Unused boost switching regulator should be connected as follows:

Pins SWBSTLX and SWBSTFB should be unconnected and Pin VIN2 should be connected to VIN with a 0.1uF bypass capacitor.

And unused LDO regulators should be connected as follows:

Input pins of the LDOs should be connected to output of a regulator with voltage lower than 3.4V with a 1.0uF decoupling capacitor and the output pins should be unconnected.

Regards,

Jose 

[hazar_mutgan]

Hello Alberto,

In the PF3000 datasheet, notes on Figure 36, states that:

Unused LDO: output can be left floating. Connect input pin to GND if not shared with other LDOs.

Is there any disadvantage of connecting input of unused LDOs to GND instead of output of a regulator with voltage lower than 3.4V as you suggested?

Thank you in advance,

Best Regards,

Hazar

[reyes]

Hi Hazar,

There are no disadvantages, unused LDO outputs can be left floating and inputs can be connected to GND if not shared with other LDOs.

Regards,

Jose