PF0100 with < 3.3 V Vin

[varsmolta]

Can I use a PF0100 (used to power the i.mx6) with a < 3.3V Vin input. We'd like to use a triple NiMH source (3*1.2V = 3.6V but the discharge can lead the source voltage to go as low as ~3.2V)The reason I ask is that SW2 buck is capable of outputting 3.3V (which can be used for peripherals like SD, eMMC) but can it output this voltage if the input Vin is < 3.3V? The PF0100 datasheet says that Vin can be in the range of 2.8V - 4.5 V. Can the entire chip work as prescribed as long as the Vin voltage is in this range or will some bucks not work because Vin is lower than the buck's capable outputs? Thanks

[JorgeRama_rezRi · Accepted solution]

Hi Varsmolta,

Unfortunately, in this case, the only regulator that's capable of output a voltage higher than its input is SWBST. So if you need any other regulator to output 3.3V, the input voltage has to be higher than this. The chip works from 2.8V to 4.5V as specified in the datasheet, but the restriction is: The output of the switchers and LDOs has to be lower than their inputs.

Best regards.

Jorge.

[varsmolta]

If I have to use a 3.6V NiMH supply or a single cell 3.7V Li-Ion supply, can I use a boost converter to boost this voltage to ~4.2V and then input this voltage to the PF0100? I understand I'd be going thru two stages (boost and PF0100) which would reduce my efficiency (say ~90% efficiency per stage). Is this a viable solution?