# Multiple Step-Down Voltage Rails from a single DC Power Supply

I have one working PCB which has three different Voltage Rails: 3.3V, 4V and 1.8V. They are generated using three separate step-down buck converters. The input voltage to all the converters is a single DC Power Supply (12V).

• Buck Converter Generating 4V powers 4G LTE Module (Load 2.5A)
• Buck Converter generating 1.8V powers LoRa IC SX1301 (Load 1A)
• Buck Converter generating 3.3V powers iMX6ULL System-on-module (Load: 3A)

These three different buck converters are occupying alot of PCB space and increasing the BOM. I am thinking to implement single IC solution for my system. A quick google search landed me on two solutions.

• A Triple Step-Down Converter from TI (TPS6526x)
• Using a single Buck Converter to generate multiple voltages. (The link is over here).

What should I consider? Is there any different solution other than listed above?

EDIT: The LoRaWAN IC is SX1301 and it requires 1.8V power supply.

• Can’t you use the same 3.3V supply for at least the SX1231 and iMX6ULL? (maybe also the unnamed LTE modem) – Michael Dec 29 '18 at 19:38
• Sorry. The IC is SX1301. – abhiarora Dec 30 '18 at 4:17
• The single point option for all three power supply using TI webbench works, as long as you use all the components mentioned in their BOM..only problem I find is if the IC fails, all three power lines will go for a toss as also pointed out in one of the answers. Do look deeply for Reliabilty of IC, along with operating temperatures when you go for full load. – AKR Dec 30 '18 at 10:45